Blower Motor

[Jlaa]

@RicardoD I cannot remember what I read to arrive at this hypothesis:

The regulator is basically a big power transistor. Whatever is in there --- BJTs/MOSFETs/Whatever --- there is enough current that goes through there (depending on the voltage on the yellow wire that feeds it) that the designer fit a big porcupine heatsink on there to prevent overheating of the transistors. The transistors critically rely on airflow to keep it cool and extend its service life.

On the facelift models, there is a dust/pollen filter there that, if not replaced when clogged, can impede airflow and thereby cause the regulator to undergo more thermal stress than usual, thus reducing service life. For that reason, my uneducated guess would be that you would want to maximize the quality/robustness of the regulator that is installed.

Additionally, at least on the preface lift models, while replacing the blower is straightforward affair (6 hours first time, of which 4 were cleaning, and then 1 hour subsequent time), replacing the regulator has some additional tedium with:

1) fishing the grommet / control wires through the hole in the fake firewall
2) a bit of stress in that that you don't want to crash the porcupine quills into the delicate fins of the heat exchanger
3) the white plastic blower-coffin-seal is really fiddly after it gets removed from its channel

So replacing the regulator is something that is not particularly pleasant to repeat.

 

[Jlaa]

BTW @RicardoD - when you replace the regulator, I would be interested to learn if the post facelift models have this same "magic screw" that the preface lift models have. In the preface lift models, the removal of the magic screw allows for bending the plastic panel, which then allows for removal of the regulator below it without having to invent new cusswords.

I understand that replacement of the regulator on post facelift models has a similar set of challenges w.r.t regulator removal, which some people have worked around by unbolting the old transistor from the old heatsink and installing the new transistor to the old heatsink with new thermal paste. I also understand that this workaround has its own set of challenges as KAE glues its transistors to the heatsink whereas OE units have their transistors screwed on (removable) to the heatsink.

Attached are pictures of the preface lift setup from my notes and the post facelift setup from @nocfn --- I am unsure if @nocfn's post facelift setup also contains a magic screw. If it does, then it is possible that removal of the magic screw would allow for easier regulator heatsink replacement.

 

[RicardoD]

Is your existing regulator bad, or do you just want to replace it proactively while installing a new blower motor (which is a good idea)?

Occassionally, my blower motor doesn't work. But if I turn off the car or fiddle with the HVAC blower motor speeds I will come back to life. So that must be a regulator issue? Or is there a deadspot on the blower motor?

 

[RicardoD]

Howdy D - there is some info about post-facelift KAE vs. MB OE regulators here: Windshield wiper not retracting / extending properly

Jlaa, thanks for the link. Like Gerry advises in that thread, I think I will end up BOGU (bend over grease up) and just go OEM for the regulator. Yet, another reason for me never to sell this car despite my desire to get a Tesla.

 

[gsxr]

Occassionally, my blower motor doesn't work. But if I turn off the car or fiddle with the HVAC blower motor speeds I will come back to life. So that must be a regulator issue? Or is there a deadspot on the blower motor?

Ricardo, this is *probably* a worn motor, especially if you hit a few potholes or speedbumps and the blower springs to life.

The regulator is generally a binary failure - either works (maybe not as new), or doesn't work at all. They don't work one day, and not the next, then work fine the day after, etc.

The PBU is another possibility, btw. If there is no speed signal voltage from the PBU to a brand-new regulator and motor, the motor will not turn. Not sure I've ever seen that happen (yet).

 

[RicardoD]

Thanks Dave,

I ordered the Behr service motor from Autohaus AZ and may simply service the regulator heat sink with new thermal grease if possible. Although I think I am still on the original regulator. I am also not sure if the 1994 regulator has a serviceable heat sink where I can freshen the thermal paste. Or do all regulators eventually fail, and I am fooling myself thinking it will make it to 250k miles (it is at 184k now).

 

[nocfn]

I changed my regulator 30 days after I installed a new Behr fan. I hate the same job twice.

 

[gsxr]

I ordered the Behr service motor from Autohaus AZ and may simply service the regulator heat sink with new thermal grease if possible. Although I think I am still on the original regulator. I am also not sure if the 1994 regulator has a serviceable heat sink where I can freshen the thermal paste. Or do all regulators eventually fail, and I am fooling myself thinking it will make it to 250k miles (it is at 184k now).

The OE regulator can be removed, and the thermal paste replaced, although I'm not certain how much difference fresh paste makes. The regulators will eventually fail, but can last a long time. It's tougher if you don't know how old it is, i.e. if a previous owner already had it replaced.

I've only recently discovered that the regulators can start to fail such that they appear to mostly work fine, except high speed isn't as high as it should be... more of medium speed. I noticed the high speed was wimpy on my high-mile (240k) E420 daily driver and was scratching my head as to why. Long story short, the regulator was the culprit. Measuring current draw will identify if this is an issue; the wimpy high speed was only pulling 15-18A, and with a good regulator high speed should be around 25A. Use an inductive clamp-type ammeter at the 30A strip fuse to measure current draw. EDIT: Make sure the ammeter will read DC current! Less expensive ones only read AC current.

When a regulator has totally failed, you either get zero fan (assuming the motor is good), or a fixed fan speed.

 

[RicardoD]

Use an inductive clamp-type ammeter at the 30A strip fuse to measure current draw.

Note to self: when buying a cheap clamp type ammeter on Amazon, make sure you buy one that support DC Amps for use on your car.

 

[Jlaa]

Thanks Dave,

I ordered the Behr service motor from Autohaus AZ

Good choice! Pls post pics! I would be curious to find out if the facelift-behr-hella-service blower units are also assembled in the USA with motors made in Canada.

 

[RicardoD]

I did order and receive via Autohaus the Behr-Hella service part against part #: 1248200608 (motor with dust filter)

Photos of stickers on the motor. Looks like motor from Canada, and assembled in the USA. The motor number appears to be different than the one you have which makes sense considering the MB part is different for 1994. Although clearly my motor has sticker on top of another sticker (perhaps that is how they change the part number!!! doh!) . The Behr Hella sticker has the exact same part numbers as what you put in your car.

All I got in the box was the motor assembly with fan. I didn't get any other brackets as shown in the photo for this part. What did you get Jlaa?

 

[Jlaa]

I did order and receive via Autohaus the Behr-Hella service part against part #: 1248200608 (motor with dust filter)

Photos of stickers on the motor. Looks like motor from Canada, and assembled in the USA. The motor number appears to be different than the one you have which makes sense considering the MB part is different for 1994. Although clearly my motor has sticker on top of another sticker (perhaps that is how they change the part number!!! doh!) . The Behr Hella sticker has the exact same part numbers as what you put in your car.

All I got in the box was the motor assembly with fan. I didn't get any other brackets as shown in the photo for this part. What did you get Jlaa?


View attachment 91029

View attachment 91027
View attachment 91028

since the unimotor sticker has an arrow indicating direction of rotation, it looks like someone put on the sticker, then realized that the sticker was on upside down, and then put on another sticker right side up on top of the first sticker!

I did not receive any brackets or clips either.

 

[RicardoD]

Finally put my DC ammeter on my car blower motor near the 30A strip fuse. ($30 Ammeter from Amazon) Hope this data helps others for a fan / regulator combo of unknown age. I have no records indicating they were every replaced.

At the Low speed fan setting I got 5.3 DC Amps
At the High speed fan setting I got 23.7 DC Amps

So it appears my fan & regulator are in good working order at the unknown age (could be originals). I have my spare blower motor but have not yet purchased the regulator for my spare parts inventory. Fan seems to have quieted down recently so I am just going to let things be for now. My high speed fan current draw is close enough to the 25A target GSXR suggested.

 

[luckymike]

Well, my blower motor has quit. Tested out of the car it works with power supplied.

Can one test the resistor or do you just buy new?

 

[emerydc8]

So it appears my fan & regulator are in good working order at the unknown age (could be originals). I have my spare blower motor but have not yet purchased the regulator for my spare parts inventory.

Regarding the regulator, I just ordered one from Naperville (124 821 21 51) for my 94 with the dust filter ($303.40). Rene just emailed me and said that there are none available in the US and it will be coming from Germany. Is this an indication that this part will soon be on the NLA forever list?

 

[gerryvz]

Regarding the regulator, I just ordered one from Naperville (124 821 21 51) for my 94 with the dust filter ($303.40). Rene just emailed me and said that there are none available in the US and it will be coming from Germany. Is this an indication that this part will soon be on the NLA forever list?

Not at all. It just means that there is currently no stock in US distribution warehouses. Nothing to do with availability.

Pretty much every order I make I have at least one part that has to come from Germany. Not a big deal.

Here's my latest:

[SIZE=5][B]Updated Order Details[/B][/SIZE] Order ID: [B]33988[/B] Order Status: [B]In Progress[/B] JUST AN UPDATE: Please be advised that the part/s 124 470 52 64 and 124 320 09 89 you ordered is not in stock at any of our US warehouse locations. The part is only available in Germany. The lead time for parts shipping from Germany is approximately 5-7 business days we will update tracking as it becomes available. thank you, Renee...

If this part ever DID go NLA, IIRC there is the KAE aftermarket version available. Not optimal from a quality perspective, but better than nothing.

 

[gerryvz]

Can one test the resistor or do you just buy new?

Best to buy a new factory unit. You can get aftermarket from the usual suspects, but buyer beware.

 

[emerydc8]

After waiting four weeks, I was informed today that the regulator for the dust filtered cars is now NLA. Not even in Germany. Naperville confirmed this and said that it was unlikely that MB would be making any more of them. Any recommendations as to an alternative brand?

AutohausAZ has the Kaehler https://www.autohausaz.com/pn/1248212151 Is that risky? Our forum list shows KAE inconsistent and "not recommended." What's left?

 

[nocfn]

KAE is all that is left, get two of them wherever you can. Mine is still working fine - the KAE and it has been a few years now of constant use.

 

[gerryvz]

Yep -- if not available from the factory, then you pretty much HAVE to go Kaehler. They are not nearly as poor quality as URO or Trucktec, so you can and should certainly use them. KAE is just not a top tier quality manufacturer.

 

[gsxr]

KAE is ok. Not OEM, but far above URO-type junk.

Six years ago, the KAE regulator I installed in my sister's W124 was made in Germany, and it is still working fine today. Please let us know what you receive, i.e. is it still made in Germany?

Photos below are from summer 2014.

EDIT - I just realized Jon is talking about 1994-95 regulators used with dust filters. FCP claims KAE is made in Germany but I don't have any photos of the late-style KAE or box/label.

 

[northNH]

Last fall I replaced the noisy but normally regulating original blower motor in my late 420 with a new Behr unit. I left the original regulator in place, working perfectly since.

Recently my 200K mile early 300CE’s (smooth quiet) blower went from occasionally to frequently inoperative, to irretrievably dead 3 weeks ago.
I removed it’s still-good replacement Behr motor (Made in Germany) and a failed German KAE regulator, both installed ~10 years ago before I owned the car.
I replaced them both with the used original German MB blower/regulator pair from a sitting-for-10-years 90K mile 400 parts car...Back in business.

Regarding the seemingly NLA genuine MB late regulator, based on the cost of a new KAE unit (and the failed one I threw in the trash), if I couldn’t come up with a good used OE one, I would buy a $22 Chinese one.
(Ten years ago I passed on a $120 OE Japanese voltage regulator for my JD tractor for a $22 Chinese knockoff; no issues since.)

But rather than mount a potentially shorter-lived Chinese regulator “correctly” deep inside the blower motor housing, I would just lengthen the regulator-to-motor wires by ~2ft and instead mount the regulator next to where it plugs into the firewall connector and run just the red and green motor wires to the blower motor. Might do the same with a used one...
Now trivial to replace, still virtually invisible, and should stay cooler too.

And BTW, you know the pair of rubber drain tubes for the early central screen unit, unearthed during motor/regulator R&R?

1958-1993 Mercedes-Benz Water Drain 124-628-00-69 | MB OEM Parts

1958-1993 Mercedes-Benz part # 124-628-00-69 - Water Drain

www.mboemparts.com

~$90ea discounted...WTF?

 

[emerydc8]

Thanks guys. I ordered the KAE from FCP Euro. I'll take pictures of the unboxing to show where it was made.

 

[gerryvz]

I believe if you have an early car (pre-facelift), there is an aftermarket Behr/Hella regulator available, which is of good quality.

Facelift owners are relegated to KAE only as an aftermarket product. KAE is acceptable, but not as good as Behr/Hella.

 

[RicardoD]

Ugh.....

I am right behind you on the KAE thing for my parts stash. Need to throw it into my replacement blower box.

 

[luckymike]

Last fall I replaced the noisy but normally regulating original blower motor in my late 420 with a new Behr unit. I left the original regulator in place, working perfectly since.

Recently my 200K mile early 300CE’s (smooth quiet) blower went from occasionally to frequently inoperative, to irretrievably dead 3 weeks ago.
I removed it’s still-good replacement Behr motor (Made in Germany) and a failed German KAE regulator, both installed ~10 years ago before I owned the car.
I replaced them both with the used original German MB blower/regulator pair from a sitting-for-10-years 90K mile 400 parts car...Back in business.

Regarding the seemingly NLA genuine MB late regulator, based on the cost of a new KAE unit (and the failed one I threw in the trash), if I couldn’t come up with a good used OE one, I would buy a $22 Chinese one.
(Ten years ago I passed on a $120 OE Japanese voltage regulator for my JD tractor for a $22 Chinese knockoff; no issues since.)

But rather than mount a potentially shorter-lived Chinese regulator “correctly” deep inside the blower motor housing, I would just lengthen the regulator-to-motor wires by ~2ft and instead mount the regulator next to where it plugs into the firewall connector and run just the red and green motor wires to the blower motor. Might do the same with a used one...
Now trivial to replace, still virtually invisible, and should stay cooler too.

And BTW, you know the pair of rubber drain tubes for the early central screen unit, unearthed during motor/regulator R&R?

1958-1993 Mercedes-Benz Water Drain 124-628-00-69 | MB OEM Parts

1958-1993 Mercedes-Benz part # 124-628-00-69 - Water Drain

www.mboemparts.com

~$90ea discounted...WTF?

northNH, I'm very interested in your idea of remote mounting the regulator. Mine has just quit and a new KAE is on the way from fcpeuro.com.

I'm no expert on how regulators regulate but don't they depend on the air movement caused by the fan? You say it should stay cooler if mounted up by the firewall connector and I sure want to believe this (having dealt with the regulator before, I can see NO way to replace the whole thing and have only replaced the electrical part, leaving the aluminum porcupine in place).

Just wanted to run past you my thought of the porcupine needing the air flow from the fan.

 

[gsxr]

The regulator generates massive heat, which is why it's bolted to a heat sink many times the size of the regulator. It's located in a place that has constant airflow from outside the car, to cool it. While this setup is a nuisance to access, it generally allows the OE regulator to last for 15-30 years at a time (assuming the blower motor is good, and not drawing excessive current).

If relocating the regulator, in any location that doesn't have a steady external air supply, the heat sink would need to be larger... or, it would need a blower feeding it cooling air. Otherwise, the regulator will likely fail prematurely due to excess heat. I'm not saying it wouldn't work, just that some R&D is recommended for the relocation.

 

[luckymike]

The regulator generates massive heat, which is why it's bolted to a heat sink many times the size of the regulator. It's located in a place that has constant airflow from outside the car, to cool it. While this setup is a nuisance to access, it generally allows the OE regulator to last for 15-30 years at a time (assuming the blower motor is good, and not drawing excessive current).

If relocating the regulator, in any location that doesn't have a steady external air supply, the heat sink would need to be larger... or, it would need a blower feeding it cooling air. Otherwise, the regulator will likely fail prematurely due to excess heat. I'm not saying it wouldn't work, just that some R&D is recommended for the relocation.

Thanks, gsxr. That's kind of what I was thinking.

I'd like to piggy-back here and ask how in the world people replace their '94-'95 regulators?? I couldn't find a way to remove that heat sink for the life of me and wound up just getting new thermal paste and screwing the new regulator onto my old heat sink.

I'd rather replace the whole thing but is it possible from inside the engine bay?

 

[mikeym]

Thanks, gsxr. That's kind of what I was thinking.

I'd like to piggy-back here and ask how in the world people replace their '94-'95 regulators?? I couldn't find a way to remove that heat sink for the life of me and wound up just getting new thermal paste and screwing the new regulator onto my old heat sink.

I'd rather replace the whole thing but is it possible from inside the engine bay?

ha... if you wiggle it just the right way, it comes out. I tried it for too long and ended up breaking the few pieces of plastic grille.
Still can’t believe how expensive this part is...

 

[luckymike]

ha... if you wiggle it just the right way, it comes out. I tried it for too long and ended up breaking the few pieces of plastic grille.
Still can’t believe how expensive this part is...

Okay, if you say so! I'll try it again when the part arrives. Yes, it does seem expensive, even at one half the dealer price.

 

[emerydc8]

Thanks guys. I ordered the KAE from FCP Euro. I'll take pictures of the unboxing to show where it was made.

I received the KAE regulator from FCP Euro today. The regulator purports to be made in Germany. There is a Mercedes part number on the plug. Could this be an OEM part? For $140.25, I just ordered another to have as a spare. Note that this is for the later models with the cabin air filter.

 

[gsxr]

Thanks for the pics, Jon! The plastic electrical connector appears to be an OE item, but most likely it was easier for KAE to buy them from MB than bother having some produced. Otherwise it looks different than the OE Bosch regulator, which is bolted to the heat sink with two Torx screws. I don't even bolts in your photo, which makes me wonder how it's attached?

 

[luckymike]

Same part I received Monday. Glad to have it. I considered buying a spare at that price but then remembered FCP has lifetime guarantee. Has anyone taken advantage of that? I mean, wipers, for instance, are going to need to be replaced every year so do they send you a new set?

gsxr, I removed the cap from the back of the regulator, expecting to see mounting screws. Nope. That's a little scary because it means if I can't find a way to get this installed, I can't fall back on removing the regulator and attaching to my existing heat sink. Great.

 

[gsxr]

Same part I received Monday. Glad to have it. I considered buying a spare at that price but then remembered FCP has lifetime guarantee. Has anyone taken advantage of that? I mean, wipers, for instance, are going to need to be replaced every year so do they send you a new set?

Although I've never used it, the catch with FCP's warranty is that you have to send back your defective part, at your cost. Depending on the item, it may cost more in shipping than it's worth. Expensive stuff is definitely worth it, but heavy or cheap (i.e., brake rotors or wiper blade refills), not so much.

gsxr, I removed the cap from the back of the regulator, expecting to see mounting screws. Nope. That's a little scary because it means if I can't find a way to get this installed, I can't fall back on removing the regulator and attaching to my existing heat sink. Great.

@Jlaa found on pre-facelift cars there was another screw which allowed the plastic to lift up, and allow the early-style regulator to be removed easily. I can't recall if the same is possible on the facelift models with dust filter and smaller regulator, but it's worth further investigation...

 

[geraniumtr]

Dave, the answer is no. The plastic cradle in my face lift 94 E320 cannot be removed. Last year I put in a K.A.E. regulator which as you note has the heat sink bonded to the regulator. It was a wrestling match to R & R. I thought I would crack the cradle but I did manage to get it installed with no damage.
As you mentioned the OE regulator has its heat sink screwed , not bonded, to the regulator.

Regards,

Peter Weissman

 

[emerydc8]

So I just installed the KAE regulator and factory motor. I'm only getting 2.6 volts at the motor when I'm calling for high fan. The 30 amp strip fuse on the driver's fender is fine. I'm getting 12 volts at the bottom of the screw and 12 volts on the top when I re-install the fuse. I have a spare control head and I swapped that out and got the same results -- about 2.6 volts when the fan is selected to high and 1.5 volts when on medium.

Any thoughts? The fan stopped working before I replaced these components, which is why I replaced them to begin with.

 

[emerydc8]

I went further back to where the regulator plugs into the connector, behind the three vacuum connectors. Measuring the voltage across the two outside pins (black and yellow), I am getting 9.6 volts with the fan on high and 4.5 volts with the fan on medium.

The fan will run if 12 v is directly applied to the fan wires.
It will run in reverse if I swap the wires.

Also, the fan will run if I apply 12 v to the black wire and a ground to the red wire (leading to the regulator). The fan will not run in reverse if I swap the leads.

With the key on and a/c selected (fan to high), I am getting 9.6 volts on the yellow terminal (mounted to car) and ground on the black terminal. No ground or voltage on red terminal.

With key on or off and O selected on a/c selector, I get ground on black and no ground or voltage on red or yellow.

So, for the base connector mounted to the car, black seems to be ground no mater what and yellow seems to be 9.6 v with the fan selected to high. I tired running the 9.6 v to the black lead going to the regulator and ground on the red lead going to the regulator but I couldn't get the fan to run with only 9.6 v.

It was my understanding that if the fan didn't run, it was either the strip fuse, the control unit in the cockpit, the fan or the regulator. I've replaced all four and still no dice. I'm not sure where to go on this one.

 

[nocfn]

If that is the proper voltage (I would have to dig it out) and you for sure have a perfect line fuse, then perhaps the CCU is the issue. Do you have a spare CCU?

 

[gsxr]

It was my understanding that if the fan didn't run, it was either the strip fuse, the control unit in the cockpit, the fan or the regulator. I've replaced all four and still no dice. I'm not sure where to go on this one.

You are correct. AFAIK, those are the only 4 components involved, other than the ignition switch (which either passes 12V, or doesn't); and the fuse supplying the control unit. There's not much in the schematics otherwise.

I believe black and red wires at the regulator are simply +/- 12V supply, fused by the 30A strip. The yellow wire is the control voltage from the pushbutton/control unit. FSM expected voltages at the yellow wire are shown in the screenshot below:

 

[emerydc8]

Thanks, Dave. I'll have to look at the rest of that troubleshooting section in the FSM.

nocfn: I do have an extra control unit. I swapped it out but no change. Maybe both are bad since I'm only getting 9.6v from the terminal that the regulator plugs into.

 

[emerydc8]

Thanks, Dave. I'll have to look at the rest of that troubleshooting section in the FSM.

This test isn't very clearly written. I'm looking at a test I have and it looks a bit different, but just as poorly-worded. Anyway, at the regulator, I am getting 1.2 volts with the fan on low. With the fan on high I'm getting 2.6 volts. WIth the temp wheel set at max hot, the voltage goes to -348 mV. Nothing I do will get the voltage over 2.6 volts. I have a known good control unit that I just swapped and I am getting the same results. So that's three control units. They can't all be bad. The next step is to measure the voltage from the terminal that feeds the regulator on my known-good car.

 

[gsxr]

Jon, it sounds like either there is an issue with supplying the control voltage, OR the regulator is bad. The regulator needs 6-10 volts to enable max fan speed. For grins, what do you measure if connecting the old regulator?

I agree that three faulty control units seems extremely unlikely. Another long shot - what happens if you disconnect the auxiliary pump in front of the CAN box? If that pump is shorted or drawing excess current, it can make the control unit do weird things. I'd also check the fuse which supplies voltage to the control unit, and clean the contacts... won't hurt.

Also - your measurements back in post #87 seem correct, for control voltage at the yellow wire (9.6v high speed, 4.5v medium speed). If you still measure the same with the regulator disconnected (from the chassis, at the 3-pin connector).... that would seem like the control unit is working. But if you connect the regulator and the yellow voltage now drops very low, AND the blower motor doesn't run, that could be a defective regulator...

 

[emerydc8]

Thanks Dave. I tried the original regulator and got pretty much the same voltage on the tests, so I think the regulator is okay too. One thing I haven't done is measure the voltage coming out of the good car's power supply to the regulator behind the three vacuum pods. If it's 12v and not 9.6 v, then I know there's a problem there. I replaced fuse 7 and no change. I may just tap a 12 v wire and send it to the regulator plug. There are two cube relays in the inboard aft relay tray with 30A Delco integral fuses in them. Neither of these control the regulator voltage correct?

 

[gsxr]

One thing I haven't done is measure the voltage coming out of the good car's power supply to the regulator behind the three vacuum pods. If it's 12v and not 9.6 v, then I know there's a problem there. I replaced fuse 7 and no change. I may just tap a 12 v wire and send it to the regulator plug.

Not sure I follow you on this...?

There are two cube relays in the inboard aft relay tray with 30A Delco integral fuses in them.

If you mean in the relay section (back half) of the fuse box area, those 2 fused relays are for the twin electric cooling fans ahead of the condenser. One relay for high speed, one for low speed. They should be different ratings, and different fuse sizes though.

Neither of these control the regulator voltage correct?

Correct... the regulator feed voltage (red/black wires) comes from the ignition switch (AFAIK) and fused by a 30A strip fuse by the strut mount, and the regulator control voltage (yellow wire) comes from the HVAC control/pushbutton unit. The ETM will have schematics on this.

 

[emerydc8]

Not sure I follow you on this...?

I'm talking about the voltage coming from the plug right behind the three vacuum pods, pictured in post #87. The plug that the regulator wire harness connects to. On the black and red terminal, I'm not getting any voltage out of those, so the only voltage I'm getting to the regulator under the motor is from the yellow control wire. I verified that I need 12v to the black wire to get the fan to run but I'm getting nothing.

 

[nocfn]

That is where Klink told me to check the voltage to ensure the CCU/PBU was operational. I will dig out my notes....

 

[emerydc8]

Thanks. If I'm not getting the voltage there I'm not sure where the wire goes behind the firewall as it makes its way back to the CCU. Strange thing is that the blower fan just suddenly stopped working one day when I switched from air to EC, just as if a fuse was blown. Maybe the wiring diagrams will show a fuse somewhere in there other than just the external 30 amp strip fuse.

 

[nocfn]

blower control voltage coming from the AC pushbutton unit. It should be somewhere between three and six volts between the little tiny one of the three wires, and body ground. If I am remembering correctly, it is a yellow wire, but it's very easy to tell, because it is a much smaller diameter than the two big blower supply wires.
If you have no or low voltage there, your pushbutton unit could be wonky. That's rare, but it does happen. Sometimes it's just a solder joint inside the pushbutton unit doing that.

The pigtail of the regulator connects to that plug on firewall, which is the harness from the push button unit

 

[gsxr]

I'm talking about the voltage coming from the plug right behind the three vacuum pods, pictured in post #87. The plug that the regulator wire harness connects to. On the black and red terminal, I'm not getting any voltage out of those, so the only voltage I'm getting to the regulator under the motor is from the yellow control wire. I verified that I need 12v to the black wire to get the fan to run but I'm getting nothing.

Got it. I believe you should definitely be getting 12V at the black+red (pins 1+2) of that 3-pin connector, with the ignition switch on.

Thanks. If I'm not getting the voltage there I'm not sure where the wire goes behind the firewall as it makes its way back to the CCU. Strange thing is that the blower fan just suddenly stopped working one day when I switched from air to EC, just as if a fuse was blown. Maybe the wiring diagrams will show a fuse somewhere in there other than just the external 30 amp strip fuse.

See attached schematics. There is NO other fuse. Power comes from the battery, goes to the ignition switch, when ignition switch is in RUN position it energizes circuit 15X which is dedicated to the blower motor, this goes to the 30A strip fuse (as of mid-1987 model year), which goes to the 3-pin connector (X64).

If you are not getting 12V at X64, the fault must reside upstream, meaning either the ignition switch or the fuse, or wiring. Have you physically removed the 30A fuse yet, to inspect & clean the contacts?

 

[gsxr]

BTW, Jon, it would help to compare the readings from your other car since it's working normally!