seattle_fleetwood Posted February 27, 2005 Report Share Posted February 27, 2005 I know this question has probably been asked a million times, but the heater on my '91 Deville is warm on the passenger side and cold on the driver's side. I read on this message board that it's caused by a faulty vacuum actuator, but I couldn't figure out which actuator it is (assuming it's on the driver's end of the heater box)...Has anyone fixed this problem theirself, and if you did, which actuator did you change? Thanks for your help. Link to comment Share on other sites More sharing options...
Northstar Posted February 27, 2005 Report Share Posted February 27, 2005 Take the glove box out and look at the air mix door actuator movement. Link to comment Share on other sites More sharing options...
Ranger Posted February 27, 2005 Report Share Posted February 27, 2005 Flushing the heater core may also solve your problem. Link to comment Share on other sites More sharing options...
adallak Posted February 27, 2005 Report Share Posted February 27, 2005 I remember Guru saying that partially blocked (clogged) heater core may result in uneven heated air distribution to the outlets. In other words say driver side is hotter than the passenger one. I just looked one more time at the diagram in the service manual and frankly do not see how it may happen . Air mix door (or valve) is actually regulates the portion of the air floe which bypasses the heater core. In one position it will completely blok the access to the heater core (60 degrees setting) and the other extremal position will direct all the air flow through the heater core (90 degrees setting). You may try to remove the glove box (that's easy) and set the temp at 90 and watch the programmer (lets call it a motor) moving the actuator slowly to one position, then change the temp. to 60 degrees and the door should slowly move to another (closed) position. Sometimes the actuator gets somehow unsnapped and the door does not response properly to the programmer position. You might want to check this out despite I am not sure it will fix the problem. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Ranger Posted February 27, 2005 Report Share Posted February 27, 2005 I think the theory of the plugged heater core is that the core gets sediment in the bottom half so that there is no flow through that portion. As the stratified air flows throught the duct, only the top half gets heated and then diverted to the passenger side and the cold, lower half gets diverted to the drivers side (or vice versa). Link to comment Share on other sites More sharing options...
Regis Posted February 27, 2005 Report Share Posted February 27, 2005 I think the theory of the plugged heater core is that the core gets sediment in the bottom half so that there is no flow through that portion. As the stratified air flows throught the duct, only the top half gets heated and then diverted to the passenger side and the cold, lower half gets diverted to the drivers side (or vice versa). That's a terrific explaination Larry. "Burns" rubber " I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. " Link to comment Share on other sites More sharing options...
adallak Posted February 27, 2005 Report Share Posted February 27, 2005 I think the theory of the plugged heater core is that the core gets sediment in the bottom half so that there is no flow through that portion. As the stratified air flows throught the duct, only the top half gets heated and then diverted to the passenger side and the cold, lower half gets diverted to the drivers side (or vice versa). Ranger, I understand the logic behind that theory, but the air (heated as well as cold) gets mixed before it is separated to particular outlets. At least that's what I see... The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Ranger Posted February 27, 2005 Report Share Posted February 27, 2005 Adallak, I thought about that too. Maybe it differs on different models or years, I am not sure. I do remember Guru explainig it this way. Perhaps on some models or years it gets delivered to the cabin shortly after it passes through the heater core and before it has a chance to mix. Link to comment Share on other sites More sharing options...
seattle_fleetwood Posted February 28, 2005 Author Report Share Posted February 28, 2005 Thanks for all the input, I did take out the glove box and watch the actuator move back and forth, like it was supposed to, I think. The heater core theory actually makes sense for a few reasons: 1) the bottom half of the ductwork that comes right from the firewall is cold (and that's the 1/2 that gets directed to the driver's side)... 2) the heater system as a whole is only slightly better than warm (after 20 minutes of idling, and yes a new thermostat) whereas I remember my old '88 CDV being like a sauna, and 3) I recently lost the hose that goes from the heater core "T" to the thermostat housing because it was lined with 'crap'. Thanks again for all the tips guys, I really appreciate the help. I'll give the heater core a shot, and if it helps, make a new post Link to comment Share on other sites More sharing options...
Ranger Posted February 28, 2005 Report Share Posted February 28, 2005 Better to stick with this post for the follow up so we all know what the original problem was. Link to comment Share on other sites More sharing options...
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