Need Help With Climate Control

[Rennbay]

Yep, we'll have an exclusive group buy for Carpokies. IDK what the sale price will be. Someplace between stupid cheap and extraordinarily reasonable.
The sticker situation is still a little up in the air. These might just be sans-stickers for the Carpokes sale and you can come back and buy the stickers on their own when available if you need them.
You must be a member here to get in on the early release sale. Also, if you are purchasing a bunch to re-sell (totally cool by me), I do ask that you hang on for 60 days before Ebaying your stash, but rebuilding units to sell immediately is A-OK.

I think that covers most of the details. I'll touch base here on Monday when we have parts in hand.

[j.samper]

Yep, we'll have an exclusive group buy for Carpokies. IDK what the sale price will be. Someplace between stupid cheap and extraordinarily reasonable.
The sticker situation is still a little up in the air. These might just be sans-stickers for the Carpokes sale and you can come back and buy the stickers on their own when available if you need them.
You must be a member here to get in on the early release sale. Also, if you are purchasing a bunch to re-sell (totally cool by me), I do ask that you hang on for 60 days before Ebaying your stash, but rebuilding units to sell immediately is A-OK.

I think that covers most of the details. I'll touch base here on Monday when we have parts in hand.

That sounds great Travis, thank you.
I am working also on some stickers (like my graphics kit that sold here), but improved with new vendor and updating for the illuminated buttons like the a/c buttons.
Had planned on doing the a/c control unit stickers, like everything, some details to iron out, but if you are having them done I will check that from my projects. Or if you are still looking at alternatives, let me know, maybe I can help.
I have like 5 units that need the plate. I would love being able to install it and put them up for sale.

[Tom]

Looking forward to our Carpokes exclusive on these clear plates. Thanks Travis! If you had pictures to share, it might help drum up business.

Re the sticker, I'm guessing there'd be a market for temperature readings in Fahrenheit. I'd get one for sure.

Ironically, Mr. Daniel Fahrenheit -- the guy who made the scale -- was German, yet here we are with Celsius readings in our German cars.

[Don_Cote]

I would definitely be interested in the stickers as well. My console switches need refurbishing as well. Can’t wait to get a new clear faceplate.
Don

[kjell]

Edit in case I buried the lead with a TL;DR post.... The CC unit is probably not working right and why you are stuck on heat. Most people would toss it and find a new one. My comments below are for people interested in trying to diagnose and repair a bad climate control unit....


Now, re the blown capacitor. I believe that is C1 on the circuit board, a 25V 47uF electrolytic capacitor. It would be easy enough to swap out that capacitor, but something most likely caused it to burn up -- meaning a new one would likely suffer the same fate if you don't sort out the cause. Check your fuses too to see if whatever blew that capacitor also took out a fuse.

The CC unit has two unique voltage rails -- one is ~6.5 volts and the other is closer to 11 (battery voltage minus 2). Both are created with zener diodes and transistors, rather than a dedicated chip. The 6.5v rail helps create references voltage for the chip (4201A) that control the heater motor. The 11 volt rail is the supply voltage for all the 4201A chips that control the servo motors. The capacitor that blew on your unit hangs off the 11 volt rail (to ground), so there's a good chance none of your motors work via the CC unit -- have you checked?

I would check to see if that voltage rail is dead by probing the pcb pad shown below. If you still have voltage there, then it's possible something downstream of the voltage regulator circuit blew the capacitor, such as a blow 4201A chip. If there is no voltage, then the rail is probably dead, and more likely a blown zener diode or transistor (which should be available). If it's a blown 4201A chip, I have them. When mine blew, I discovered they were obsolete and had to buy the remaining stock (like 150+ of them for like $20) from some vintage chip dealer in the UK -- which at the time were the only ones anywhere I could find anywhere. Not sure how electronicsy you are and if this is any help or not? Like I said, I'd be happy to take a shot at fixing it if helpful. You can also get used ones on eBay, but you never know what you're going to get....


hvac 11v rail check.gif

Howdy, I'm just swinging by to ressurect this thread!
I have a 1986 NA with the basic heater control and since I got the car a couple years ago haven't been able to get any of the controls to work at all aside from the fan speed. So to get heat I hotwired wired the heater matrix solenoid to a switchable 12V source but I've finally decided to revisit the heater controller and try to actually fix it...
I've been trying to follow the logic of testing but haven't found a schematic for this type of control unit. Any ideas?

HVAC controller.jpg (138.99 KiB) Viewed 7466 times

Using the official carpokes HVAC diagnostic test chart I've found that I have good readings on heater mixer control and defrost flap control motors and pots, however on the footwell control I can hear the motor move but don't get a resistance reading (∞Ω). I do not have sensors so skipped that test, but similarly for the HVAC solenoids I had no reading for the recirc.

I also applied 12V to the pin B2 and 0V to B4 in attempt to see the voltage rails and can confirm that the reading on the pad referenced in the picture I've replied to is 2V less than my supply. I fail to find 6.5V anywhere when probing around though the higher voltage appears on numerous connector pins on both plugs A & B.

Any thoughts are much appreciated!

[Scooter]

IMG_9872.jpeg (3.68 MiB) Viewed 6840 times

Thanks everyone so much for this post. It was very detailed and helpful since I have the exact same capacitor fried. I am now looking for a capacitor or complete assembly.

[Damo]

Edit in case I buried the lead with a TL;DR post.... The CC unit is probably not working right and why you are stuck on heat. Most people would toss it and find a new one. My comments below are for people interested in trying to diagnose and repair a bad climate control unit....


Now, re the blown capacitor. I believe that is C1 on the circuit board, a 25V 47uF electrolytic capacitor. It would be easy enough to swap out that capacitor, but something most likely caused it to burn up -- meaning a new one would likely suffer the same fate if you don't sort out the cause. Check your fuses too to see if whatever blew that capacitor also took out a fuse.

The CC unit has two unique voltage rails -- one is ~6.5 volts and the other is closer to 11 (battery voltage minus 2). Both are created with zener diodes and transistors, rather than a dedicated chip. The 6.5v rail helps create references voltage for the chip (4201A) that control the heater motor. The 11 volt rail is the supply voltage for all the 4201A chips that control the servo motors. The capacitor that blew on your unit hangs off the 11 volt rail (to ground), so there's a good chance none of your motors work via the CC unit -- have you checked?

I would check to see if that voltage rail is dead by probing the pcb pad shown below. If you still have voltage there, then it's possible something downstream of the voltage regulator circuit blew the capacitor, such as a blow 4201A chip. If there is no voltage, then the rail is probably dead, and more likely a blown zener diode or transistor (which should be available). If it's a blown 4201A chip, I have them. When mine blew, I discovered they were obsolete and had to buy the remaining stock (like 150+ of them for like $20) from some vintage chip dealer in the UK -- which at the time were the only ones anywhere I could find anywhere. Not sure how electronicsy you are and if this is any help or not? Like I said, I'd be happy to take a shot at fixing it if helpful. You can also get used ones on eBay, but you never know what you're going to get....


hvac 11v rail check.gif

I found this thread today when troubleshooting why the temperature control has no effect in my car. I also worked out that the feet and demister vent controls have no effect - none of the flap motors move. When I bought the car a few months ago the aircon switch was broken so I replaced that and found it had the same burnt capacitor which had burnt a hole in the board. I replaced that at the time to the best of my ability (very amateur with electronics!).

Today I tested pin 5 from the image in Tom’s post above and it only reads 0.7v instead of 11v, so it seems my climate control unit is dead. Given how badly burnt the capacitor was would it be salvageable or should I go looking for a replacement?

[Tom]

Edit in case I buried the lead with a TL;DR post.... The CC unit is probably not working right and why you are stuck on heat. Most people would toss it and find a new one. My comments below are for people interested in trying to diagnose and repair a bad climate control unit....


Now, re the blown capacitor. I believe that is C1 on the circuit board, a 25V 47uF electrolytic capacitor. It would be easy enough to swap out that capacitor, but something most likely caused it to burn up -- meaning a new one would likely suffer the same fate if you don't sort out the cause. Check your fuses too to see if whatever blew that capacitor also took out a fuse.

The CC unit has two unique voltage rails -- one is ~6.5 volts and the other is closer to 11 (battery voltage minus 2). Both are created with zener diodes and transistors, rather than a dedicated chip. The 6.5v rail helps create references voltage for the chip (4201A) that control the heater motor. The 11 volt rail is the supply voltage for all the 4201A chips that control the servo motors. The capacitor that blew on your unit hangs off the 11 volt rail (to ground), so there's a good chance none of your motors work via the CC unit -- have you checked?

I would check to see if that voltage rail is dead by probing the pcb pad shown below. If you still have voltage there, then it's possible something downstream of the voltage regulator circuit blew the capacitor, such as a blow 4201A chip. If there is no voltage, then the rail is probably dead, and more likely a blown zener diode or transistor (which should be available). If it's a blown 4201A chip, I have them. When mine blew, I discovered they were obsolete and had to buy the remaining stock (like 150+ of them for like $20) from some vintage chip dealer in the UK -- which at the time were the only ones anywhere I could find anywhere. Not sure how electronicsy you are and if this is any help or not? Like I said, I'd be happy to take a shot at fixing it if helpful. You can also get used ones on eBay, but you never know what you're going to get....


hvac 11v rail check.gif

I found this thread today when troubleshooting why the temperature control has no effect in my car. I also worked out that the feet and demister vent controls have no effect - none of the flap motors move. When I bought the car a few months ago the aircon switch was broken so I replaced that and found it had the same burnt capacitor which had burnt a hole in the board. I replaced that at the time to the best of my ability (very amateur with electronics!).

Today I tested pin 5 from the image in Tom’s post above and it only reads 0.7v instead of 11v, so it seems my climate control unit is dead. Given how badly burnt the capacitor was would it be salvageable or should I go looking for a replacement?

Sounds like that board is shot. An old school electronics tech might be able to fix it, but it's probably easier to find a replacement on eBay or the like. I can look at it if you want -- even a blind hog finds an acorn once in a while Before writing it off, have you checked the motors themselves using our handy-dandy diagnostic charts?

https://www.carpokes.com/viewtopic.php?t=357

[Damo]

Thanks Tom. I've tested the 3 sensors and all were within spec. I didn't have an easy/safe way to get 12v to the pins to try each of the motors yet but I'll do that before deciding what to do next.

[Tom]

Thanks Tom. I've tested the 3 sensors and all were within spec. I didn't have an easy/safe way to get 12v to the pins to try each of the motors yet but I'll do that before deciding what to do next.

Did you see the video? It shows the little cigarette lighter hack I used to get 12v for testing....