1985 Riviera Electronic Climate Control Module

[Guest bigskymusiclover]

Greetings my 1st post here, I own a nice 1985 Riviera, I am having some problems with the Electronic Climate Control Module, at 1st the motor that controlled metal door right in the center bottom of dash would run all the time the rest of the system would work fine, I monkeyed around with that and found that if I stuck a stick up the vent holding that door closed all was well. Well that fix only lasted about 15 mins, the system went totally "nuts" after that. All the lights on the ECC head went crazy then it just went dead. All that happens now it the system is stuck on high heat and I can hear other doors or flaps moving, but the large one at dash center bottom stopped moving. Remove the battery power over night has no effect.

I pulled the AC fuse and they whole system is dead now. I don't know were to go from here!!!!!???? I checked some prices on the ECC head and it's going for over 100 dollars new I can't afford that. Maybe the ECC head just needs some caps or parts replaced at the component level?

THANKS FOR ANY AND ALL HELP>

[sosuzguy]

Sounds like it could be the control module in the dash but to know for sure you are going to have to follow the trouble shooting steps in the service manual to see exactly what the problem is unless you want to just start replacing parts. The SM has you put the system in certain setttings and will let you know what's wrong with it by blinking the LED after you make changes. That or try another Head unit in the dash.

[Guest bigskymusiclover]

The touch panel is totally dead it won't responded to any settings. I ordered one from a place on car parts hopefully I won't get ripped off. I have not been able to find any service manual for the car, It's not on CD that I know of. Thanks

[sosuzguy]

The Riviera Owners Association has service manuals in the library and a long list of Technical Advisors who can assist ROA members. The Climate control section can be obtained through either.

[NTX5467]

(Compared to the semi-automatic a/c control I looked at for a '90s S-Blazer, at about $750.00 retail, or the electric mode actuators now for $250.00 each . . . )

As you'll probably discover, there are some doors which are partially-open, fully-open, or "bleed" closed in particular combinations to make the air come out of certain vents and such, "on cue". Seems like there is even an electric motor to run the heater's water valve?

Other thing is that if you keep an electric motor from doing what it's wanting to do . . . mechanically . . . some "smoke is going to be let out of the box". Might be an internal fuse inside of the motor housing? When that motor couldn't do what something was telling it to do, there might have been some "feedback" voltage which went places it shouldn't have gone.

BEFORE putting the new control unit in and hooking it up, DO go through the diagnostics referenced above to look for possible REASONS the system was acting as it was BEFORE installing the replacement control head!!!! If you plug the new head in and the (possibly) shorted motor does not respond to commands, it could damage the part you just purchased. Unfortunately, "no returns on electrical parts" is highly common in the automotive parts industry, for good reason. With THAT in mind, you might also seek out the particular mode actuator that runs the door which you blocked from moving and replace it too (as you'll probably need to replace it also).

So . . . seek out the referenced "library" above BEFORE you do anything else--period. Take the time to fully comprehend how the system operates and what the sensors are and where they are, plus how they affect the system's operation.

One OTHER thing might be to check the alternator's output . . . i.e., "charging system check". Reason I mention that is that the later electronic-style GM hvac controls can become unresponsive when the alternator output becomes lower than normal. When we were doing "Extended Service hours to Midnight", I came to work at 5pm and sold an a/c control head for a Chevy Malibu (complaint was that it wouldn't change modes). At 10pm, that same car came back on the end of a tow hook . . . it quit running. When we did a charging system check, the alternator output looked "good" when it had very little load, but when load was increased (with engine rpm at about 2000rpm), the voltage started to decrease quickly with additional load. When the voltage got below 5 volts, the instrument cluster lights flashed in pairs "in a certain sequence" right before the engine died. With a new GM reman alternator, everything was back to normal and the hvac control worked great. If somebody had thought to check the alternator output FIRST rather than simply replace "the obvious" (right before the tech was going to go home for the day), that customer might not have needed the tow truck . . . although extended warranty paid for the hvac control and everything else . . . except for the inconvenience of the whole situation.

Please keep us posted on your progress.

Respectfully,

NTX5467

Edited April 6, 2013 by NTX5467 (see edit history)

[Guest bigskymusiclover]

Thanks for the post and info, I am not able to access the library it keeps wanting a username and password. I don't have funds to pay to join the club right now. Can someone email me the HVAC section? My email is my handle at gmail.com

[Rivieraman]

Bigskymusiclover

where are you located at?

[Guest bigskymusiclover]

Southwest Montana 59711

[Rivieraman]

have you taken your control head to a shop to have it rebuilt?