W140 A/C not working – best approach to DIY repair?

[JC220]

Hi all, for those who may not have seen my owners thread I have recently acquired a 1997 facelift W140 S280 Saloon with 45k miles on it. The car has spent most of its life in garages not being used. It has just been resuscitated and returned to the road and I am concentrating on getting everything up & running again on it.

The A/C never did work in it. The EC button is lit up all the time and will not go off if you press it. With the lack of use and years standing I have figured it will have lost quite a bit of it’s A/C charge. Does this mean it’s leaking? It’s a given that any auto A/C system will lose in around 10% of charge each year. Regular use circulates the Oil in the system which helps keeps all the O Rings and seals.... sealed. A car which see’s no use at all will leak the refrigerant faster. I hope there are no “real” leaks but I will find that out only when I gas it up again.

I was planning on taking it to a garage with A/C equipment but I’m not so sure now. They will only evac and fill up and if it leaks it’s a waste of money. AKA about 80 USD a go and if it’s leaked out overnight after the service then you’re right back to square one. I will add UV dye on the first fill up so at least that might leave a neon S$^t stain where it would be leaking.

In Ireland there are practically no specialist A/C repair shops since we don’t really need it at all & most car’s don’t have it.... I may invest in the relatively cheap gauges and vacuum pump to enable my own A/C servicing at home on several of my car’s. Hell it would be nice to check each car every year and top them off to keep things in tip top order.

In the W140 Climate control it can self diagnose. When I do that it is coming up with all of the following error codes:

• B1231 – ECT sensor (B11/4)
• B1234 – Sun sensor (B32)
• B1241 – Refrigerant fill
• B1423 – Switchover valve block (Y11)
• B1417 – Duovalve (Y21y1), left
• B1418 – Duovalve (Y21y2), right
• B1416 – Coolant circulation pump (M13)
• B1459 – Series interface (K2) connection to instrument cluster (A1)

This does seem like ALOT of codes for a low miles car. This car has no eco junk (1997 model year) apart from the wing mirrors (already repaired by me) and one part of the A/C loom that I recall Klink mentioning. Could these codes be a result of the Eco Junk?

And can anyone – or Klink advise on where I can find & inspect the Eco Junk w140 AC wires?

Edit - I also just bought this DIY style A/C kit and a second can of the gas. I will add some plain gas first and if the pressure begins to drop in a few days I'll go ahead with the stop leak product too.

 

[Rouven036]

I suggest to re-fill the ac, add UV dye and then clear the fault codes and see if the system works (ac compressor engages) If not then start troubleshooting on the electrical side. If the system works just continously use it until the ac stops working or you can start to hear a hissing sound from inside the dashboard caused by low gas level. Then start for a leak search. My guess is that the system will work since the main issue is either its empty due to a too long time not operated or a leak. I had replaced several w140 evaporators (check for UV dye marks on the condensation drain hoses in the tunnel from below) also behind the auxiliary fan motors (brush dust causes electrolysis damage) are common leaks on the condenser to find (also sometimes leafs in the lower section of the auxiliary Fans causes the condenser to corrode). Now and then some leaking seals or hoses. However also not properly closing heater valves can cause the system not to cool.

 

[LWB250]

I would say do one of two things:

1.) Buy the tools to do the work yourself. If you do any AC repairs in the future, such as replacing a compressor, you'll have paid for them multiple times over.

2.) Take the car to an AC specialist. They're going to pull it down to see if it will hold a vacuum. If not, they'll likely pressurize the system with nitrogen and some dye to find the leak if it's not obvious. They won't put refrigerant in it if they don't know the system is intact - it's not only wasteful but in some locales it's illegal.

I have owned a number of W140s and have done my own AC work for some years - I live in Florida and it's a survival skill here - so feel free to ask questions. There are diagnostics you can run from the ACC panel that can give you some idea of what's up and if there are fault codes in the system. I don't have it handy but can find the link to the test procedure to display the system operation through the panel. Here is a list of the fault codes that could be displayed for reference:

026 CAN Bus Communication
226 In-Car Air Temperature Sensor
227 Outside Air Temperature Sensor
228 Heater Core Temperature Sensor
230 Evaporator Temperature Sensor
231 Engine Coolant Temperature Sensor
232 Refrigerant Pressure Sensor
233 Refrigerant Temperature Sensor
241 Refrigerant Level
416 Coolant Circulation Pump
417 Left Duovalve (Water Valve)
418 Right Duovalve (Water Valve)
419 A/C Compressor Electromagnetic Clutch
420 Closed (Idle) Throttle Speed Increase
421 Pulse Module
422 Serial Interface Connection (K1) to Instrument Cluster
451 Diverter Flap
452 Blend Air Flap
453 Fresh/Recirculated Air Flap Long Stroke
454 Fresh/Recirculated Air Flap Short Stroke
455 Defroster Outlet Flap Long Stroke
456 Defroster Outlet Flap Short Stroke
457 Footwell Flap Long Stroke
458 Footwell Flap Short Stroke
459 Serial Interface Connection (K2) to Instrument Cluster
462 Wide Open Throttle (WOT) Position Signal - Diesel Engine Only

More in a bit after I get done fixing dinner. By then you'll probably be asleep, so look for it in the morning....

Dan

 

[LWB250]

While I'm waiting for the outdoor oven to heat up to finish a couple of filets, I dug around and found the link:

http://manual.startekinfo.com/manual/JSP/cc/3_6/content.jsp

Click on section 15/1 and follow the instructions to read out the DTCs (diagnostic trouble codes) for a start:



Let us know what you get after running the test.

Dan

 

[JC220]

Guys – thanks for your replies. Regarding the vacuum pump and “pro” gauges I was going to buy them but I think there is little point. Reason being it is irresponsible and illegal as already mentioned to allow the old gas to leak out. So in order to a proper service in the first instance you must have the correct equipment to recover the old refrigerant and oil safely – which no home user can have without considerable investment.

From your replies and thinking more about it I am going to do the following next:

1. Carefully check that there isn’t already any UV dye traces visible from existing AC leaks
2. Take to my local garage who do have the correct equipment for evacing the system and re-filling with the UV dye and Oil qty as per spec. I do want to make sure any moisture or acid is removed from the system now rather than just adding in more refrigerant on top (to a possibly neglected system) The garage owner knows me and has done my cars before with the instructions to hold them on vacuum for an hour or two before re-gassing to make sure it won’t just leak right out again.

I’ll clear the codes from the system after that and drive it for a few days to see how it performs and also record what fault codes may still remain. If it does drop out again due to low gas then I will carefully re-inspect for where the dye leaked out and repair any issues present

Dan – I did run the diagnostics on the system and the first post shows what codes are coming back at present. Any other pointers would be great!

 

[LWB250]

Dang! Did I gloss over that to begin with or did you go back and repost those?

Sorry....

Agreed - the best tack to take at this point is to clear codes, drive the car, attempt to use the system (both heat and AC) and after a few days see what comes back. In all of the W140s I've owned the codes I always found were legacy codes, as few aftermarket service places bother with looking at the DTCs or they don't know how to access them.

Also - you won't have "eco junk" wiring in a facelift (1996-later) W140. That ended with the end of the 1995 model year. Count your blessings!

Dan

 

[JC220]

Dang! Did I gloss over that to begin with or did you go back and repost those?

Sorry....

Agreed - the best tack to take at this point is to clear codes, drive the car, attempt to use the system (both heat and AC) and after a few days see what comes back. In all of the W140s I've owned the codes I always found were legacy codes, as few aftermarket service places bother with looking at the DTCs or they don't know how to access them.

Also - you won't have "eco junk" wiring in a facelift (1996-later) W140. That ended with the end of the 1995 model year. Count your blessings!

Dan

That’s OK! (They were there in the first post I created at the start) When I have it charged again I’ll try to read and understand the sensor values too.


I would still be very interested in what loom is the eco one for the w140 late model AC system. I would like to repair that if it needs it done. Yes it is Eco Junk free BUT Klink on here advised even the 1997+ w140 still have Eco junk in 2x areas. The power wing mirrors and one part of the AC harness..... he was right about the wing mirrors. The first time I power folded them back they blew a fuse and would not return until I removed and re-wired them. Here are pics of the Eco wiring from the wing mirrors. The car is a 1997 build originally delivered in Singapore. I have checked the engine harness etc and it's A1 not Eco Junk. A delphi tag is above the starter motor too. But I do belive Klink that there is one other area Eco junk will still be present in my 1997 in a part of the AC system.......

 

[JC220]

This is it's VIN decoder

https://www.datamb.com/vin/4bGQrAaO0x7EOkm5B

 

[LWB250]

The wing mirrors have been eco junk throughout production, unfortunately.

I'm not aware of an AC harness that's eco junk, at least not in any of the facelift W140s I've owned. If it's an interior harness, best to leave well enough alone as they are rarely a problem. The only other harnesses I can think of are the one that goes to the duo valves and AC compressor.

The duo valves can be problematic, as the diaphragms can fail. Believe it or not, there are repair kits available in Australia of all places, but nowhere else in the world that I know of.

Dan

 

[Trae]

Do all year model W140s have the same failing evaporators like our 124s, or did they figure things out after 1996?

 

[LWB250]

No. Up through MY 1995, roughly. If you have a 96 or later you should be fine.

Dan

 

[JC220]

The S is booked into a garage tomorrow who has the proper A/C equipment. I'll update the thread when I get it back tomorrow evening and clear the codes etc. Hopefully there isn't a leak or ill have my second S Class sized repair Bill (Post gearbox rebuild just completed)

 

[outrbnks]

That’s OK! (They were there in the first post I created at the start) When I have it charged again I’ll try to read and understand the sensor values too.

The power wing mirrors and one part of the AC harness..... he was right about the wing mirrors. The first time I power folded them back they blew a fuse and would not return until I removed and re-wired them. Here are pics of the Eco wiring from the wing mirrors. The car is a 1997 build originally delivered in Singapore. I have checked the engine harness etc and it's A1 not Eco Junk. A delphi tag is above the starter motor too. But I do believe Klink that there is one other area Eco junk will still be present in my 1997 in a part of the AC system.......

View attachment 76826 View attachment 76827 View attachment 76828

Wow, this is the first I've read of the Eco wires being a problem "OUTSIDE" of the engine compartment.

The mantra I've always read was the engine heat environment caused the problems, but now it appears the the engine heat accelerates the problems, and other wires in these cars "may" also degrade, but at a much slower pace. I always wondered if the rest of the wires in the entire car would last over the years.

So I have 4 e class cars, 3ea 92's, and 1 ea 94. The 92 CE still has original wires to my knowledge, (with no problems), and the 2 92 500's have had the typical harnesses & eta changed or rebuilt. The 94 e420 the same.

Should I expect latent problems in the mirrors of my cars as well? Are there any other wiring areas in our mid 90 E classes that may become problematic for wire insulation degrading?

 

[JC220]

Wow, this is the first I've read of the Eco wires being a problem "OUTSIDE" of the engine compartment.

The mantra I've always read was the engine heat environment caused the problems, but now it appears the the engine heat accelerates the problems, and other wires in these cars "may" also degrade, but at a much slower pace. I always wondered if the rest of the wires in the entire car would last over the years.

So I have 4 e class cars, 3ea 92's, and 1 ea 94. The 92 CE still has original wires to my knowledge, (with no problems), and the 2 92 500's have had the typical harnesses & eta changed or rebuilt. The 94 e420 the same.

Should I expect latent problems in the mirrors of my cars as well? Are there any other wiring areas in our mid 90 E classes that may become problematic for wire insulation degrading?

Yes I was quite surprised at this myself! Apparently, thewing mirrors are very problematic on the w140’s. Perhaps because the wires were“extra” eco friendly in composition or more likely that the power folding action (Which is neededquite often for the bulk of a w140) causes extra stress on the wire insulation integrity.

Bearing in mind this car has spent many years of it’s lifein a cold Irish Garage it’s doubly dubious. (VS Texas heat or similar)

The early CIS injected W124’s are Eco Junk exempt thankfully. All HFM / LH models are not as we are aware. I would expect w124 mirror problems to be minimal given that they are not power folding the wires are not under much stress. But who knows in the coming years what else will crop up.

Other than the Engine upper + lower harness, AC harnesses in the engine compartment, ETA’s and Gearbox Harness Eco junk failures in other areas are quite rare. For me the most common other area is the rear trunk hinge I have seen them degrade there. There are also a limited number of w124 fires reported in the past as there are unfused wires in that location. (The trunk lamp IIRC) This can result in a fire under the dash board – but again is very rare. I have had to repair these trunk harness areas on ALL my w124’s and it is an important place to check.

I do recall also seeing someone replace interior wires too under the dash because of eco junk but these instances thus far are few & far between.

I found the snipet from before where Klink spoke of the W140 EcoJunk in facelift models:

There’s no eco-junk wiring in that one except for the exterior mirrors, and the connector pigtail harness on the pollution sensor for the ACC, if so equipped.

 

[JC220]

The car goes to the garage for re-charge tomorrow. Tonight I fitted a new pollen filter (Perhaps there are others too but I got this one done anyway) The one I removed was dated 2005. Took the opportunity to squirt some Wurth Dry lubricant into the fan blower bearing since it’s staring at you with the pollen filter out.



Second – I waited until dusk and went over the whole system with my UV Lamp. To set a benchmark for when it’s freshly gassed up again. All lines and fittings + the condenser were totally clean of Dye. It did not come out very well in the picture but I am seeing some very fine traces of yellow / green UV Dye in around the A/C pump fittings and at the front face of the pump body. Just VERY slight spattering.



I will ask the garage to pull and hold a vacuum on it for an hour or two before filling it up tomorrow to ensure this is not an active leak. It would suck for 100$+ of gas to leak out in the days after the service but it could happen...... if it does I’ll try the STP A/C stop leak product myself before getting a whole new or rebuilt A/C pump.

 

[LWB250]

For what it's worth (Wurth), the best lube for the fan bearings is ATF. A couple of drops it all it takes. Not sure about the Wurth stuff, but I'm sure it's OK.

The only other filter in the car is the activated charcoal filter that's down in the cowl, and it's not a service item. Not to mention you don't want to have to replace it - the procedure is not fun.

It's likely that the front seal on the compressor has worn, and refrigerant is slipping past it during operation. Very common point of leakage, especially if the system isn't used much or the car has sat for a long time. It's a $USD 5.00 part and an easy replacement with the compressor off the car, but most shops will insist on replacing the whole compressor, which is rarely necessary.

The process is such that they will pull a vacuum and if it holds at or near 28-29" of Hg, they'll turn off the vacuum pump, close the service valves, and start the timer. If it leaks down faster than 30 minutes to an hour, you've got a leak that must be addressed. Also be aware that this car does not have barrier hoses, that is, hoses that have a physical barrier to prevent refrigerant from leaking out of the hoses at the molecular level. While this can take a very, very long time, as the hoses age it will get worse. This is the typical system that needs a can of refrigerant every year to keep it charged.

Of course I would defer to your AC guys, but the very best sealant I have ever used in automotive AC systems is called "ClipLite" and made by a Canadian company. This stuff will seal some of the worst leaks outside of compressor shaft seals, which can't be fixed with a sealant, of course. I've even sealed W124 and W140 evacuator leaks with it and it will hold.

https://www.amazon.com/Cliplight-Super-Premium-Automotive-Conditioning/dp/B0002NYBC8?ref=ast_p_ei

Great company, you can actually call and talk to an engineer if you have questions, just like RedLine (at least you used to be able to talk to people at RedLine, I'm not sure these days.) My 1995 E300D does a great job with AC, but it has the original hoses that will allow a charge to leak off in about six months. I put a can of ClipLite in it and it's been going strong ever since.

Good luck, keep us posted!

Dan

 

[gsxr]

^^^ Everything Dan said is spot on.

Additional info: Cliplight, which is made for leaks in hard parts (condenser, evaporator), does not help fix leaks in O-rings, seals, or other 'soft' parts. Use a different sealant product for those types of leaks. I tried this stuff (FJC 9140 Stop Leak) for grins because it was cheap, and was shocked to find it actually made a substantial improvement in 2 different cars. Apparently on those cars, a decent chunk of the leak was on soft parts... a 94 E420, and a 97 W210.

Also, if you are going to try Cliplight, I would recommend their top-of-the line product. This used to be called Super Seal Total Auto, and is now re-named Super Seal Platinum. The part number is the same for either one, 976KIT, it's just different packaging for the same stuff. Link below. Be warned that it can be a PITA to get into the system, after following the instructions to the letter, you may also need to heat the can gently (!) to coax the product out of the can and into the system. (I had to heat the FJC can as well for one of the 2 cars.) The built-in drying agent is the main extra item you get in the top-line 976KIT product, IIRC:
http://www.cliplight.com/hvacr/chemical-tools/super-seal-automotive/super-seal-platinum/

 

[LWB250]

What he said, with a caveat:

The Platinum stuff is good, but in the cases where I've used ClipLite I have replaced the receiver/dryer before evacuating the system, making the use of a drying agent unnecessary. If you're just pulling down an already (nearly) empty system and don't plan on replacing the receiver/dryer, then the drying agent is appropriate to use.

Dan

 

[gsxr]

What he said, with a caveat: The Platinum stuff is good, but in the cases where I've used ClipLite I have replaced the receiver/dryer before evacuating the system, making the use of a drying agent unnecessary. If you're just pulling down an already (nearly) empty system and don't plan on replacing the receiver/dryer, then the drying agent is appropriate to use.

Ooops. I forgot to mention that... Dan is right, if you have replaced the receiver/dryer and vacuumed the system properly, you shouldn't need the drying agent.

Now that the W124.034/.036 receiver/drier is a dealer-only item at $170 MSRP, it's more enticing to not replace it unless necessary; or if a new compressor is being installed. Dunno if 140 driers are still available aftermarket.

 

[LWB250]

Now that the W124.034/.036 receiver/drier is a dealer-only item at $170 MSRP, it's more enticing to not replace it unless necessary; or if a new compressor is being installed. Dunno if 140 driers are still available aftermarket.

Pretty sure they are, at least a year or two ago they were. No more W140s in my garage, thank you. And with that I have a lot more time on my hands, too...

Dan

 

[JC220]

The S280 has been with the garage all morning and they phoned to say it's passed all leak tests AOK and still had gas in it when the machine was hooked on.

They say it's came back on and working properly so I can pick it up during lunch at work. I'll let you guys know how it holds up in the coming days

Thanks for all the input- I appreciate it!

 

[LWB250]

Great news! We like those easy repairs!

Dan

 

[JC220]

I picked it up and drove it back to work. All is good - blowing ice cold air and no EC light on. When I re-ran the A/C diagnostics it's now showing zero faults

I love easy fixes too! Fingers crossed the gas stays in it for the foreseeable future and I'll keep the A/C serviced annually now

 

[LWB250]

Excellent!

But given where you live, will you ever need it?

 

[JC220]

Excellent!

But given where you live, will you ever need it?

I'll require A/C at least 3 days in the year! It's actually most useful for de-misting the windows in winter here. In any case I cannot sleep at night if anything is not functioning properly on my car

 

[LWB250]

In any case I cannot sleep at night if anything is not functioning properly on my car

Oh my gosh, a kindred soul. And to think of all the abuse I’ve taken over the years because I go to the trouble to make sure something as insignificant as the light bulb for the ash tray/cigarette lighter works!

There is hope for us....

Dan