ECC possessed!

[Scandude83]

I just bought a 95’ n/a 850. Having issues sorting out the culprit on why my HVAC fan and compressor work, at best, intermittently.
Sometimes, I will start the vehicle and everything works as it should. Air blows cold. Then, it will either stop all together or sort of stutter and blow a bit, then stop. At first, the lights on the ECC were flashing, but i’ve pulled the flash codes and cleared them once. It also seems that when it starts “acting up,” none of the controls (fan speed, on/off) respond. Want to get some much needed advice before just throwing precious parts at the problem. The two codes that were stored had to do with both driver and passenger side temp sensing fans behind the headliner shorting to ground/frame (which I already attempted to clean and can see spinning when I turn the key on).

Any advice would be much appreciated!

[jreed]

There are a couple of checks and information that would help get to the root cause...
Does wiggling the ignition key cause the symptoms to come and go?
It sounds like when the symptoms start, sliding the fan speed control does not change the fan speed... is it also the case that the orange lights on the ECC panel do not come on when you turn the AC switch off or recirc switch on?

[gdog]

I just bought a 95’ n/a 850. Having issues sorting out the culprit on why my HVAC fan and compressor work, at best, intermittently.
Sometimes, I will start the vehicle and everything works as it should. Air blows cold. Then, it will either stop all together or sort of stutter and blow a bit, then stop.

If you just bought the car (how many miles?) chances are the AC compressor clutch is worn to the point that it needs to be re-shimmed. This is a PITA job but can be DIY'd w/patience. RobertDIY advocates fixing it via quick-and-dirty method w/zipties (which I don't agree with, but to each, his own..).

Then the AC system could also be low on refrigerant, which would cause it to cycle on/off too frequently. And there are other possibilities but these are most likely.

At first, the lights on the ECC were flashing, but i’ve pulled the flash codes and cleared them once. It also seems that when it starts “acting up,” none of the controls (fan speed, on/off) respond. Want to get some much needed advice before just throwing precious parts at the problem. The two codes that were stored had to do with both driver and passenger side temp sensing fans behind the headliner shorting to ground/frame (which I already attempted to clean and can see spinning when I turn the key on).

Any advice would be much appreciated!

I would not worry too much about those temperature sensor codes; common on these cars and would only affect the "auto" ECC mode.
Then "acting up" where you losing control of the fan switch is more concerning. It could be ignition switch but more likely the ECC control switch itself.

[Scandude83]

Thanks so much for the advice.
I do believe it is something internal to the ecc, as the compressor has started kicking on and off in coincidence with the “aut” light’s flickering on the compressor switch. Seems shorted.

I guess my next question would be-
Is there a write up on temporarily bypassing ecc, by wiring in a switch for both the fan and the compressor…

I’ll end up getting another ecc, but meanwhile, it’s hot!

[Scandude83]

Oh, and it’s a fairly high mileage car (276k), but previous owner went above and beyond with service and records. It’s the gold edition in a nice metallic green.

[gdog]

Thanks so much for the advice.
I do believe it is something internal to the ecc, as the compressor has started kicking on and off in coincidence with the “aut” light’s flickering on the compressor switch. Seems shorted.

I guess my next question would be-
Is there a write up on temporarily bypassing ecc, by wiring in a switch for both the fan and the compressor…

I’ll end up getting another ecc, but meanwhile, it’s hot!

Yes, good to have another ECC in your parts collection, if nothing else, to help diagnose HVAC issues.

Not sure if you can bypass the ECC switch easily, but as an FYI, this is one of Robert's better diagnostic vids:

[Scandude83]

@ jreed-
Tried wiggling the ignition and it seems to have no effect on its symptoms. However, they are erratic. The fan comes on with it switched to off, the compressor does the same. The lights on the selected functions also do not respond to their switched position and the compressor kicks on and off (exactly when the light flickers on the ecc). No real control over fan speed, or compressor.

[Scandude83]

@jreed-
The ignition key seems to have no effect on its symptoms. But no, the lights for rec/compressor do not respond to their switched position. Also, compressor kicks on “with” the shorted-looking flickering of its indicator light. Basically, no response from fan or compressor and both just sort of do what they will.

[Scandude83]

Ordered a “reconditioned” unit off of eBay.
Fingers crossed!

[Scandude83]

@gdog-
Thanks for the tip.
Robertdiy has been a godsend.
Good man!