Equipment needed for DIY A/C Service?

[JC220]

Hi All,

I have several old benzes ranging from W124, W140, W211, W220 & W204 models. Most of which are low on Freon and require an AC service. A local garage used to do that for me but it would be VERY costly to ask them to take on half a dozen cars at once

Thus I want to carry out my own AC drain, vacuum testing, oil filling and Freon filling at home. Not using the little cheapie cans with gauges on them. Ideally by buying a good used AC service machine. I'll keep a lookout.

Do any of you guys use a vacuum pump at home to empty the system? (Technically into the atmosphere I guess ) What "Bulk" gas can you buy cost effectively and do you use the pair of gauges to hook up and test / monitor the system?

I will of course start researching this now and watching You Tube videos etc. But any pointers would be appreciated.

And yes I am in Ireland - and we require AC at least 3 days a year

 

[LWB250]

Good luck finding a service machine. I've been looking for a couple of years locally and have yet to find anything. There's one that's been on the local Craigslist for about a month now that I'm tempted to go look at, but I haven't had the time yet.

Not sure if you have Harbor (Harbour?) Freight or it's equivalent in Ireland, but...

I have a HF set of manifold gauges, a HF vacuum pump, and a couple of can taps, both the screw on and clamp type. I also bought a little kit of adapter fittings to allow me to use everything with an R12 system, as I have the occasional car that uses R12.

A service machine will recover refrigerant, which you either reuse or take to a recovery station and pay to dispose of it. I screwed up a couple of months ago and bought a recovery machine, which doesn't really do me any good as I can't use it to recharge. Duh. I wasn't paying attention and didn't realize what I was buying. If there's a positive aspect of this, I got a good quality vacuum pump to back up my HF pump which has served me well for over five years.

Not sure what your environmental regulations are like there, but here in the States they're pretty rigid about handling refrigerant and its disposal. Getting a license is a pencil-whipping exercise, but disposing of the old refrigerant can be a pain if you're an average guy. The recovery places here aren't keen about taking refrigerant from a non-commercial entity.

I live in Florida where AC is a requirement, so in my case the equipment has paid for itself many times over in the years I've owned it. I buy refrigerant in the 12 ounce cans by the case, just so I always have a supply on the shelf. If I go through a case (6) in a year that's a lot. A case of six cans of good quality (DuPont SUVA) R134a used to be around $USD 30, but it's either the time of year or prices have gone up for some reason lately, as I just checked this past weekend and the best deal on a case of six cans I can find is around $USD 40-45.

There are plenty of DIY tutorials on AC service online. It's not rocket science, but like anything, you need to understand what you're doing and how to interpret the gauges or you can damage things.

Dan

 

[gsxr]

I'm not an expert on this subject, but in general you need an evacuation/recycle machine to remove existing refrigerant.

Now, if a system is empty already, all you need is a vacuum pump, manifold gauge set, 30-lb tank of refrigerant, and refrigerant scale. Avoid the cheap air-powered venturi vacuum pumps, you need a proper AC vac pump to develop deep enough vacuum to boil moisture out of the system. They aren't terribly expensive, but read the manual, I think they require the internal oil to be changed every X hours of operation. And you usually need to run it a few hours at a time to pull a system down to 29.xx" vacuum.

I assume you already know that conversions are problematic; I'm assuming you are dealing with factory R-134a systems only, that have not been modified or molested?

Edit: You can use cans as Dan describes above, however this tends to cost more. If you are refilling multiple vehicles that have empty systems, buying a tank is more cost-effective. And, using the tank allows you to more accurately measure the weight installed, and there's no waste. I've tried storing partial cans and over time they always end up leaking, and are empty when I pull them out of the cabinet a year later.

 

[JC220]

Gents thankyou for the great advice. Yes Dave all factory r134a benzes never modified.

I have a few low on freon that likely just need topped off correctly. And the S500 Coupe had zero gas in it. Possible leak I'll have to check.

It looks like gauges are the way to go. Initially I ordered a case of 6x 300gram r134a refrigerant. Next I'll compile a list of what I need. I guess I'll need to inject UV dye to enable leak detection and have the ability to add some compressor oil too? On the S500 I'll.pour the correct weight of oil into the compressor when re fitting it.

 

[samiam44]

I'd say avoid a cheap gauge set- for a DIY trying to find why a hose/seal etc isn't holding correct vacuum is a killer. If you buy a machine- make sure you replace the descant/filter. Ideally add an ounce of Nipendenso oil and re-charge by weight to an evacuated system. RobinAir equipment is junk. If you want a good stand alone vacuum pump- yellow jacket stuff is good. You can usually get a pump which is being retired by a home hvac pro for $100 which will work good enough. Always replace the oil on the vacuum pump. It has a big effect on how low of a vacuum is acheived.

As a rule of thumb, freon is cheaper in the winter months- buy it November through Feb .

Michael

 

[LWB250]

While I could probably justify buying/using a 30 pound tank of refrigerant, I just don't want to have the hassle. I rarely have an open can, and if I do I'll leave it sealed up with the tap and see if it lasts. If not, not a big deal. 30 pounds of refrigerant is a LOT, and even with the amount of AC work I do, it would take me years to use it up. If I can buy cans in the $USD 5-6 range I'm OK with that.

I would avoid using dye, it's a personal preference. Get an inexpensive "sniffer" and use it to look for leaks. Dye doesn't do you any good when it's an internal leak like an evaporator, for example.

If you can pull 29" of vacuum in the first couple of minutes the system is probably OK. What I typically do is pull a vacuum for about 10 minutes and then close off the system. I'll leave it for an hour or two, checking it every fifteen minutes or so, to see if it's leaking down. Once I'm convinced it's tight, I'll vacuum it for a couple of hours to remove any moisture from it before recharging.

Dan

 

[gsxr]

Side note about oil in the system. Information on this is pretty vague in the FSM, but the FSM does specify amounts of oil to add when a particular component is replaced, vs total oil capacity for the system. The oil is distributed throughout all components (evap, condenser, hoses, drier, compressor). The only way to remove all the oil is to flush the system after opening it, and remove the compressor to manually drain it. This generally is not needed unless you are changing from R-12 mineral oil to R-134a PAG/POE, or vice-versa.

That said, be careful adding oil! My understanding is that when removing the compressor, you pour out the oil inside and measure the amount, then add the same amount back in (or, use the FSM spec for the compressor only, if available). But you wouldn't put the total system oil fill amount into the compressor, unless you had flushed all the oil out of the entire system. Too much oil in the system will cause problems.

 

[geraniumtr]

+1 on Dave's most recent post. I'm no expert but I just changed the compressor on my 94 E320 about 10 days ago so I'll make a few comments.
I had an indy shop evacuate the system as refrigerant cannot be vented into the atmosphere. I then R & R the compressor and the receiver/dryer with new. The instructions with the new Denso compressor stated to replace the R/D. I've also read anytime the system is open you should replace the R/D.

Regarding the PAG 46 oil which is required. You remove the manifold plate from the new compressor and drain the oil. Be sure to rotate the pulley several times to empty the compressor fully. Since my old compressor had no oil in it I added 4 OZ. (120 CC) per the FSM. A new R/D also gets 10CC of oil per the FSM but this amount is negligible so I just added the 4 OZ. in total. You then swap over the old manifold connection flange to the new compressor and install it. Back to the shop for a several hour vacuum of the system. Check if system holds a vacuum and if yes add the refrigerant and dye if desired. FSM specified 1000 g of refrig. or 35 OZ. for my E320.

A/C is working great. One more thing, I replaced the 2 pressure switches on the R/D since I had the system open and at 25 years old didn't want to take a chance they might fail in the near future. Around $100 for both.

Hope this is helpful.

Peter Weissman

 

[JC220]

I have ordered a 3cfm pump and kit which includes the pump oil, manifold gauge set and can connector.

On thinking about it - most of my cars at the moment only need topping off with refrigerant since it has been a couple years at least since they last seen a service. Eg w140s appear to lose a little gas each year through the hoses or whatever.

So mostly I will be doing top offs and checking pressures.

Ref vaccing down a system. I guess this is only really relevant in 2x situations.

A: when work has been done and items replaced thus emptying out the refrigerant and potentially letting in moisture.

B: If a condenser gets hit by a rock and leaks all the refrigerant out. Same issue with the moisture getting in and the need to vac down and boil off moisture.

Does that sound reasonable? Or must you periodically have a pro machine suck all the old gas out and input new (or a mix of everyone's gas??!)

And finally the suggestion of a leak sniffer was a great idea. I ordered one of them too.

What do you do if a car wont hold vacuum? Must you add a very small qty of refrigerant and use the sniffer device to locate the leak(s)?

It's just darn strange that the S500 coupe hadn't a whiff of gas in it.... could have been taken apart before I guess and not re-gassed. Or it's been soooooo long since it seen an AC machine it has all leaked off.

Hindsight is 20/20 as they say. When removing the AC pipes from the S500's AC pump some green alien blood dripped out. Maybe I should have caught that and weighed it

 

[LWB250]

Yes, that's totally feasible. Without a vacuum pump you can't service these systems. Period.

There are a couple of ways to look for leaks:

1.) Inject dye and use a UV light; or,

2.) Use a sniffer

If the system won't hold vacuum you could charge a little and use the sniffer. If you've been working on the system or have an idea of what failed, it's not really necessary. There's probably enough residual refrigerant in the system oil that it would trigger a sniffer in a lot of cases. You also have to be aware of the common leak points - mainly the front compressor seal for older systems, it's a common place for them to fail. If you've got an old compressor it's probably got a bad front seal.

You always want to use new O rings whenever you change a component, as they're cheap insurance to avoid leaks. An assortment of the green O rings can be had inexpensively, and they're nice to have on the shelf in case you need one.

Also understand that these older cars have refrigerant lines in them that become porous as they age. Porous in the sense that from a molecular standpoint they leak. It's not uncommon to have a W140 or W124 that needs a top off every season due to such things. Whenever overhauling an AC system in one of these cars, it's a good idea to replace the flexible lines if possible. An industrial hydraulic hose shop can make them up for you using the old fittings, just take the whole line in to them. They'll use a newer, more modern hose material that has a physical barrier in it to prevent leaks at the molecular level. If you do it all like this from the get-go, your AC system will stay intact for a long time.

Dan

 

[alabbasi]

Basic tools
Vacuum pump
Manifold gauges
Basic tool kit with some oversize spanners
IR thermometer
Black Light
Yellow tint UV goggles like the ones Bono wears (he still hasn't found the a/c leak he was looking for)
Scale
Haynes AC manual (yes there is one and yes it's pretty good)

Supplies
Freon (get a 30lbs jug, it's much cheaper)
O ring set
PAG oil
UV dye

FYI, I have two R12 service machines in my possession. I may have used them once .... years ago

 

[gsxr]

Joe,

My BIL was an HVAC guy for years. The vacuum test is handy, but he would also have a cylinder of nitrogen with a regulator, and pressurize the system to see if there were any leaks under pressure. Sometimes the system may hold vacuum but not pressure. Same concept, if it holds pressure without dropping over several hours, it's OK and ready to vacuum & fill with refrigerant. This likely isn't practical unless you plan to service multiple vehicles over a number of years.

Same BIL also reported the sniffers can be dicey for leak detection, as in the sniffer alarm kept going off even when there wasn't a leak present. Dunno if he just had a bum unit (don't think it was cheap), but I do know he stopped using it and had better luck with vacuum + nitrogen testing. UV dye may be helpful.

In any case, if you determine the evaporator is leaking, consider trying something like Cliplight SuperSeal or Cryoseal before wasting 50 hours on an evap replacement. Any other component, fix/replace as needed. Our one E420 has a leaking high pressure service port; aftermarket ones were cheap but I didn't like what I received, so I shelled out for an OE one... they are visibly different. If you replace either port, get OE. And finally, the latest OE O-ring seals are purple, not green. Not sure of the material used.

 

[LWB250]

Thanks for the update on the O rings, Dave.

I second the nitrogen approach and know a number of people that do this. I've been told that getting a tank of nitrogen isn't that expensive, as it's used by the home brewing folks, so the industrial gas people regularly lease small tanks for a minimum amount of money, like $50 or less. I believe it's ideal to pressurize the system up in the 185 psi range and see if it holds pressure over a period of time. The last piece of documentation I read said something in that range, I believe.

ClipLight SuperSeal is an amazing product and can delay the need for major service or replacement for some time if you're living right. I've used it on a number of occasions and it's worked well for me.

Dan

 

[JC220]

Just from thinking about my most recent professional AC services I realise what they did may have been incorrect.

This is in relation to my 500E – serviced 2 years ago.
My w211 a week or so after the 500E
My S280 W140 serviced last year.

In each case they used their machine to evac the old gas and hold a vacuum for an hour or two to check for leaks. None of the car’s leaked but I opted for the Dye additive to cover basis in the event of future leaks.

Here is the potential problem or error on their part. They read the sticker underhood on each car and noted the QTY of refrigerant and PAG Oil. And when programming this into the machine they also added the PAG oil fill. It seems from what has been said here so far and what I have read, that in a case like this when no components have been replaced or removed that the original Oil should have stayed in the system. So those cars done by a professional shop, are likely running a double charge of PAG Oil

Anyway – my S320 W140 is an ideal candidate to start with for a top off when all the stuff gets here in a week or two. It’s AC is working but on a hot day yesterday it was not blowing ice cold air, but is getting cooler and the compressor cycling. So it has lost some of it’s charge through the non barrier hoses etc and needs a top off. The new cans of r134a I bought are plain refrigerant with no stop leak additives or anything like that.

I hope to be able to provide a nice clear, easy to follow DIY on how to top off a w124 system and the pressures when I get the hang of it!

A stitch in time saves 9 as they say. I want to keep each car topped off every year and understand how these things work! The S500 Coupe will get new seal rings where I have worked at the engine replacement, new Schrader valves from MB and a new Receiver Drier and go from there. To start with I will temporarily re-fit the compressor and condenser in order to pull a vacuum for a few hours and see just how good or bad it is leak wise.

 

[JC220]

It's quite interesting also to see how wildly the price of r134a cans of refrigerant go vary in price

Eg, At Halfrauds one 532g can is priced at £59.95gbp.

Or Fleabay is 300g for £4.34 inc postage from china. That is where I ordered a case of 6.

 

[LWB250]

Be careful about buying Chinese R134a, as you get what you pay for. No telling what’s in it.... I stick with the name brand stuff so I know I’m not putting potential junk/floor sweepings, etc., in my car.

Dan

 

[JC220]

Point on gas duly noted!

Unfortunately here in Ireland / UK we have little to zero choice when it comes to buying refrigerant for DIY use.

It's either go to halfrauds or local auto parts store and pay silly money for STP cans etc. 50 - 80 bucks a can. They do not sell anything else just the one type.

Big bottles are very expensive for a DIY prospect and also controlled whereby they will not sell to someone without a license or registered garage. And rental often applies to large cylinders.

It appears that in USA you guys are blessed with many big auto chains and can buy name brand refrigerant readily for 5 bucks odd per can.

Again - that is not the case here. The Ebay r134a gas appears to be priced more or less the same as the name brand USA stuff. And as a DIY project for me it is the only way that will make this be worth the trouble.

If I were to pay the STP price in auto stores then it would be possibly cheaper to go to a professional garage and not have to "buy" the gas at extortionate rates.

 

[gsxr]

Joe, the cans aren't quite that cheap here, but they are relatively inexpensive, I'm seeing DuPont for ~$8/can when you buy six - URL: Amazon.com: Six (6) 12oz Cans of DuPont Suva R134a Automobile Refrigerant/Freon (6 Cans): Automotive

That's roughly $10-$12 per pound, buying in cans. The 30-lb tanks can be had for ~$150 or so, which is half as much (~$5/lb). If you are only planning to service two or three cars, the cans are probably easier... but a 30-lb tank can last you 10-15 years!

 

[JC220]

Thanks for that Dave. Yes if I could buy those Dupont cans that would be best! And very reasonably priced at that. A Ebay uk search returns zero results for Dupont r134a

I see now what you mean about the larger bottle for me that would be the way to go. But again I see those are about 350 usd over here.

I will use the first 6 small bottles and make sure I have a couple of successful repairs at DIY AC then invest in a large bottle from a reputable UK source.

 

[LWB250]

Point on gas duly noted!

Unfortunately here in Ireland / UK we have little to zero choice when it comes to buying refrigerant for DIY use.

It's either go to halfrauds or local auto parts store and pay silly money for STP cans etc. 50 - 80 bucks a can. They do not sell anything else just the one type.

Big bottles are very expensive for a DIY prospect and also controlled whereby they will not sell to someone without a license or registered garage. And rental often applies to large cylinders.

It appears that in USA you guys are blessed with many big auto chains and can buy name brand refrigerant readily for 5 bucks odd per can.

Again - that is not the case here. The Ebay r134a gas appears to be priced more or less the same as the name brand USA stuff. And as a DIY project for me it is the only way that will make this be worth the trouble.

If I were to pay the STP price in auto stores then it would be possibly cheaper to go to a professional garage and not have to "buy" the gas at extortionate rates.

Actually, it ranges from $USD 7-12/can in our auto parts stores these days. Part of that cost might be seasonal fluctuations.

I stick to the DuPont SUVA brand as I know it’s good. I realize you might not have access to it there, but I put it out as a reference in case you do find a way to get it.

Here in the States getting a license to handle refrigerants is a simple online test and pay the fee. It might not be much different where you are.

Good luck!

Dan

 

[alabbasi]

Walmart sells R134a for under $5 can. It's pure R134a with no leak sealer, snake oil or anything else which is what you want. I won't be too concerned about Chinese R134a. It's a commodity and they are pretty good at making those.

 

[gerryvz]

You can get 134a for good prices also at Home Depot, in the auto section ($10/can):

CERTIFIED A/C PRO Certified A/C Pro Refrigerant 134a (12 oz.) CERT301-1

www.homedepot.com

My local store also has a cheaper brand on the shelves.

 

[LWB250]

I just bought some CarQuest R134a at Advance Auto last weekend, as I got caught with almost none of my last SUVA stash. Retail was $7.99/can, with my discount codes I think I got it at 25% off that. Normally their house brand R134 has been more like $10-$11/can, so I'm not sure what's up with this.

Dan

 

[gsxr]

I just bought some CarQuest R134a at Advance Auto last weekend, as I got caught with almost none of my last SUVA stash. Retail was $7.99/can, with my discount codes I think I got it at 25% off that. Normally their house brand R134 has been more like $10-$11/can, so I'm not sure what's up with this.

Crazy Candian prices... eh!

 

[LWB250]

What are you talking about? I'm enjoying the Matterhorn and a wonderful espresso right now (eh).

Dan

 

[gsxr]

What are you talking about? I'm enjoying the Matterhorn and a wonderful espresso right now (eh).

LOL! Didn't realize the Concorde was back in service.

✈

 

[LWB250]

Bangers and mash for breakfast.

Dan

 

[JC220]

My AC tools arrived today - it was a UK supplier I used. The gas is still at least a week out.

I think tonight I will temporarily hook back up the condenser and AC pump in my S500 coupe and pull a vacuum to see if it holds at all. I did check the pump and it does turn by hand AOK so hopefully not banjaxed altogether - unless the front seal is worn out.

 

[JC220]

I got started his evening and re-used the old O rings to temporarily connect back up the AC pump and condenser/ rad pack. Then hooked up the manifold and vacuum pump It would not even try to hold vacuum at all!

I could hear the air noise so located it to be the condenser leaking like a sieve. Then tried just disconnecting the condenser and taping off the hoses. Now it goes right down to -30 psi in a few seconds but with the machine off bleeds down over a few minutes. I guess this is the duct tape and old re-used O rings.

So I'll need to order a condenser and new seal rings first - then try again. I did let the vacuum pump run for over an hour anyway to start drawing out the moisture that will be in the system. Pretty cool to see the atmospheric moisture venting out of the little vacuum pump after its pulling vacuum for a few minutes. That is the moisture boiling off I guess.

I have 2x receiver drivers coming too. One for the S500 right now and one for them self since I have 3x W140s and they all appear to take the same one.

 

[JC220]

I have watched several videos on this subject and this one I found to be the best:

I also realise when I tried to hold vacuum the other day I had not closed off the manifold gauges. Maybe the vacuum pump itself was letting in air. Maybe I'll try again later today and see if that makes any difference at all.

 

[JC220]

OK so many, many countless hours of labour and nearly a year later tonight I had the new condenser installed, new O rings (from a generic AC kit I have not genuine as with Covid my dealer is closed) and a new receiver drier.

Hooked up the vacuum pump and this time it pulled down to the bottom of the gauge in a few seconds and I have had the pump running for almost an hour at which point I will shut it off and let it sit to see if it can hold vacuum for 1 hour. (As a basic benchmark since this is what all the garages do locally anyway) Fingers crossed it holds

Question- it is late and I did not think I would have got that much back together today.... can I just shut off the gauges and leave the system under vacuum for a few days? I have the gas but its 9pm and the exhaust still isn't on the coupe yet! Cant start it up and I want to review videos etc again anyway to be sure at what point/ pressure / weight I stop adding new refrigerant.

Second question- I guess the system is designed to hold pressure not vacuum!!

Will it do any harm to leave it under vacuum for a few days? And if its lost the vacuum next time around should I be overly concerned if a number of days have passed? If all goes to plan in a few days I'll pull a hour of vacuum again before finally adding new refrigerant.

 

[JC220]

OK so many, many countless hours of labour and nearly a year later tonight I had the new condenser installed, new O rings (from a generic AC kit I have not genuine as with Covid my dealer is closed) and a new receiver drier.

Hooked up the vacuum pump and this time it pulled down to the bottom of the gauge in a few seconds and I have had the pump running for almost an hour at which point I will shut it off and let it sit to see if it can hold vacuum for 1 hour. (As a basic benchmark since this is what all the garages do locally anyway) Fingers crossed it holds

Questionn- it is late and I did not think I would have got that much back together today.... can I just shut off the gauges and leave the system under vacuum for a few days? I have the has but its 9pm and the exhaust still isn't on the coupe yet! Cant start it up and I want to review videos etc again anyway to be sure at what point/ pressure I stop adding new refrigerant.

Second question- I guess the system is designed to hold pressure not vacuum. Will it do any harm to leave it under vacuum for a few days? And if its lost the vacuum next time around should I be overly concerned if days have passed? If all goes to plan in a few days I'll pull a hour of vacuum again before finally adding new refrigerant.

Final important point - the air ventilation/ blower fan is not working in this car! Likely as it stood too long. I can get access just now due to a issue I will resolve with a fastener. (Too tight and captive nut below is turning. Have to take the ECU box out to get to grip this captive nut and get access to the blower motor) I'll try to get this fan going before I add gas and test the system

 

[LWB250]

Second question- I guess the system is designed to hold pressure not vacuum!!

Will it do any harm to leave it under vacuum for a few days? And if its lost the vacuum next time around should I be overly concerned if a number of days have passed? If all goes to plan in a few days I'll pull a hour of vacuum again before finally adding new refrigerant.

Not at all. In fact, it will be a reference point for you to see what sort of vacuum its holding after that much time.

You can vacuum until you turn blue, it won't hurt anything. The system will get to a point of stasis where all of the moisture has been evaporated off and just stay there.

Dan

 

[JC220]

Thanks Dan - the first test was not good! Turned off the pump and the vacuum started to drop off slowly a couple of minutes later. I turned the pump back on and opened the valves again and could clearly see mist coming out of the pump. I presume there is still moisture boiling off - maybe a leak.

I leave it for a further hour and try again. Failing that I'll leave it for the night with the pump put away and valves closed off. It may still require a compressor shaft seal if they can even be changed? Or a new compressor Id have to verify the compressor IS leaking though before committing further £££ into the AC system which has been neglected for at least a decade.

 

[JC220]

OK so I gave up tonight. Several hours pulling a 30 vacuum and its leaking down to 10 after 6 mins and sits there. Not half as bad as before when it would not even pull a vacuum at all.

For now I will put the protective caps back on the new condenser and pull a vacuum on it again to keep it as new. And re-visit the AC system when the dealers open again and I can get parts. For now its get it on the road!

 

[LWB250]

Dropping down to 10" after 6 minutes indicates a pretty substantial leak, like a bad O ring. I doubt very much that a shaft seal would leak down that quickly.

As for shaft seals, I'm not sure about on your side of the pond, but over here there's a guy on eBay who sells rebuild kits for the Nippondenso compressors. It's a really easy job to do with it out of the car.

I didn't think it got hot enough around your parts to need AC?

Dan

 

[gsxr]

Dropping down to 10" after 6 minutes indicates a pretty substantial leak, like a bad O ring. I doubt very much that a shaft seal would leak down that quickly.

Agreed. Do you have a way to pressurize the system to check for leaks, other than charging it? If pressurized with nitrogen, you can use the bubble method at each fitting, but that won't allow you to check the evaporator.

As for shaft seals, I'm not sure about on your side of the pond, but over here there's a guy on eBay who sells rebuild kits for the Nippondenso compressors. It's a really easy job to do with it out of the car.

I think compressor shaft seal leaks are often accompanied by green oil leaking out the front, but you'd need to remove the pulley + clutch to inspect properly.

I didn't think it got hot enough around your parts to need AC?

 

[JC220]

Dropping down to 10" after 6 minutes indicates a pretty substantial leak, like a bad O ring. I doubt very much that a shaft seal would leak down that quickly.

As for shaft seals, I'm not sure about on your side of the pond, but over here there's a guy on eBay who sells rebuild kits for the Nippondenso compressors. It's a really easy job to do with it out of the car.

I didn't think it got hot enough around your parts to need AC?

Dan

I did use cheap generic seals from an Ebay kit supposedly for AC systems. I chose the sizes as carefully as I could but - I would much prefer to replace all accessible AC O ring seals with genuine MB items. I will do that before proceeding further and place the order as soon as the dealers open again.



I'm a bit miffed that ive likely wasted the new receiver driver but it was a NOS item that I had bought for like £15 on fleabay so not such a problem. I'll install the second new one at such times as the system actually holds vacuum!!



The drier on the car looked like the original item never changed. The old condenser was shot so I had high hopes that may have fixed it. Ah well whatever it is I will fix it for sure soon. The longer the system sits not working the more difficult it will be to diagnose and repair. W140s are notorious for evaporator issues so I could have a PITA on my hands.

Valid point on do we actually need AC in Ireland! With a sunroof that is a no in this case. Many cars here dont have AC. But I myself like climate control and do use it on my cars on a regular basis. Especially for demisting the windows!! I use AC all year round pretty much it's good for the car to keep the windows clear in winter and interior cool on the short summer season. Funny thing is last year we had a heat wave here like I've never seen in my life. It was like Spain for a few days and unbearable not to have AC.

Secondly - I really want this C140 to be the best example it can be. Having a dud AC system doesn't fit at all with that plan This coupe would have cost nearly the same as a house back in the day so I will put whatever comparatively small £££ back into it to leave it right

Agreed. Do you have a way to pressurize the system to check for leaks, other than charging it? If pressurized with nitrogen, you can use the bubble method at each fitting, but that won't allow you to check the evaporator.



I think compressor shaft seal leaks are often accompanied by green oil leaking out the front, but you'd need to remove the pulley + clutch to inspect properly.

The good thing is that this coupe will finally be road legal soon. So if I'm beat I could find an experienced AC shop (not many here to be fair!) And let them diagnose where the leak(s) are.

Although not conventional I guess I could maybe remove the compressor pully and hook up 20psi or so of shop air to the system and use leak spray everywhere accessible in the engine compartment to see if anything shows up? Including the compressor itself which would interest me most to rule out. After that then conceed defeat and take it to a garage who could add a safe gas and sniff around the dash etc. (I have a new freon sniffer tool also but not much use since the system is empty and it seems irresponsible for me to knowingly add gas to a system that wont hold vacuum. (I try not to be a d#ck when it comes to the environment)

 

[gsxr]

Although not conventional I guess I could maybe remove the compressor pully and hook up 20psi or so of shop air to the system and use leak spray everywhere accessible in the engine compartment to see if anything shows up?

I'm not sure if 20psi would do anything. The AC tech I've watched do this used a nitrogen cylinder with regulator to put 200psi into the system, IIRC... remember static pressure with system off on a hot day is easily 80-100psi.