Problem with heater/AC control

[zajo]

I searched the forums and it seems like the HVAC system is fairly complex and that exact symptoms may help diagnose a problem. So here is my situation, I hope someone can help because I'm lost:

'90 C2, ~80K miles, got it a year ago. The heater and AC worked fine until a month ago, and then it started acting: while both AC and the heater continued to work, *occasionally* even though I had left the fan knob at 1 or 2, the fan would go to the max, gradually but quickly, over a second or so. When this happened, it would not respond to the fan knob until it is turned all the way to 4, then turning it down would work just fine.

This mischief continued on and off for a few weeks. And then one day, the AC worked fine going out for a 20 miles long trip, then after a couple of hours of rest, I fired her to drive back, and -- no fan, no heater, no AC, nothing, nada, kaput.

Halp!

[tab tanner]

More than likely it's the controller going bad. Google Auto and Truck Electronics, They can rebuild the controller for you

[zajo]

T Tanner, thanks for the suggestion.

Update: over the weekend I removed the big electric fan that is in the engine compartment to test it, since I read that if it's not working nothing else will. I connected the fan directly to the battery and it is blowing like nobody's business!

I checked the 30 amp fuse, it's good. I also swapped the fan relay from the back fuse box with one of the identical relays in the front fuse box. No luck, the heater/AC system is still completely dead.

Besides dead HVAC electronic module, can someone think of something else I can check myself? Is the electric fan test I did sufficient to prove that it is working? (I know some fans are complicated and have their own control module for variable speed and stuff.)

Thanks again,
Emil

[TMc993]

Originally Posted by tab tanner

more than likely it's the controller going bad.

+1

[zajo]

So I sent the climate controller for testing/repair to autoecu.com. They said there were a few capacitors that went bad, replaced them and sent me the controller back. Net effect? No effect, the symptoms are exactly as I have described them in the beginning of this thread! :|

I do have the lifetime warranty of autoecu.com, which presumably means that if the controller is still bad they'll fix it; but at this point I have doubts.

Any suggestions on how to test this? Anyone with a 964 in or around LA willing to swap climate controllers with me just to see if mine is bad? Please email me at emildotchevski@gmail.com.

Thanks!
Zajo

[Traveller]

Try reading this, if you think the CCU is gone.

Porsche 964/993 CCU Electrical Repair

[mzcporsche]

Please read and consider carefully before using Automotive Scientific Inc. Automotive Scientific Inc. | Quality Rebuilt Automotive Electronics | Rogersville, TN
In December 2015, I needed to have my climate control unit (CCU) repaired in my 1990 Porsche. It was working and needed a small short fixed that I needed to complete the sale of my car. The cost for the service was $285.00. I experienced what I must say is the worst customer experience ever over the next 3months. As of today they will not provide me with any refund. I am reaching out to you all in the hopes you will consider the following information that I wish I had had before sending them the unit.

• They returned the unit to me 10 days later and it was no longer functioning.
• I returned the unit to them under warranty and they attempted to fix it but they were unable to fix it after sending it to me a second time.
• I called them after the 2 attempts and they agreed to let me send it to another vendor even though opening the unit voids the warranty as long as I sent them proof that the unit was fixed and what the problem was. (I spoke to Casey)
• In February, I sent it to Tore Bergvill in Norway. He was able to fix the unit to original specifications. Communication and service was way better. Here is what he said:
I am appalled by the state of this unit.. The work is of very low quality, and it has caused severe damage. I am astonished that a company will even sign and label such work.
They have changed the internal relay by glueing a newer type in place of the original. The relay was very badly attached to the PCB, and they short relay legs barely had proper contact in the solderings. There was a lot of solder flux residue, and damage due to the use of a too hot soldering iron. This is the third time I see this kind of work coming from autoecu.com.
• I called ASI and they instructed me to send the invoice from Tore with the appropriate documentation. 3.2 is sent the request to Will after speaking to Alison. There was no response from Will (the decision maker). I made over 5-6 calls over the next month to try to get them to comply with their previous terms and was ignored.
• The last call on the topic was on 3.22 where Will stated that he most likely cannot offer a refund as opening the unit voided the warranty.

In sum, there is great risk to using this service for CCU repairs. The service is not up to standards, and if you do have a problem like mine they may go back on their word, hide behind their warranty and stonewall you the whole time till you get frustrated and go away. I am out my $285 but if I can get even 1 person to avoid this experience it will have been worth the effort.