my wife has a 91 cad sedan deville 4.9l, the car has heat on pass side only, luke warm on drivers side on a 30 deg. day, freezing cold below 20 deg. any ideas?????

Does this have selections for driver and pass?

First, make certain coolant is properly filled - if low it can do that and find out why it's low.

Any recent work?

T
Tom Greenleaf - MetroWest Boston - USA
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http://www.autoacsystems.com/tomgreenleaf/

i replaced the a/c clutch and pulley last summer, radiator and recovery tank are full and coolant looks clean, single climate control, the programmer seems to be working that is all doors open and close, switches from floor to defrost, warm air pass side and cool air drivers side on floor and defrost, i also had to replace blower motor last month after jump starting it with hammer didnt work anymore, i called the only local caddy dealer for help, and they just want to help themselves to my money!!! i really dont mind paying someone for repair work, but the car has 160k on it and i dont feel it is worth $500 in repairs from the dealer, i want to trade it off but my wife has a love affair with this car, and already has threatened divorice because of my suggestions, maybe its the t stat?? maybe the water pump?? air in the system??? i'm all out of guesses

Ok: There's just one core as source of the heat but apparenetly isn't making it to driver's side. I'm not quite sure why this system can be warm/hot on one side and nothing on the other unless a hose has come off somehow - but that's not adding up yet either.

Did this just start with the blower motor? Was there any critter nests noted - I'm not kidding!

Probably not the water pump but could be the heater core itself doesn't get good flow thru it. The core is closer to passenger's side so it would be more effective but not that noticeable!?

T-stat - maybe. From cold just feel the upper radiator hose....... it should stay cold for quite a while until t-stat opens when engine is warmed up. If it feels warm in a few (3-4) minutes from stone cold the t-stat is passing too much coolant thru too soon and would be in question. The total supply of warm/hot coolant would normally handle extreme temps as you know. Careful of course but feel the hoses going to firewall - when fully warmed up they are pretty dang hot - even return shouldn't be stone cold again.

Just a test - try plugging the outlet air with a towel on side that gets warm and report if heat then comes out driver's side - I'm still thinking of what to do for this??

T
Tom Greenleaf - MetroWest Boston - USA
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http://www.autoacsystems.com/tomgreenleaf/

the problem actually started middle of last winter, but was not as bad as this winter, plugging the pass side outlet wont work, there are separate doors for each side, i will try to explain as best i can, i'm not sure of part descriptions, i removed the plastic outlet at bottom of heater box and lets say looking up at heater box under dash there are 2 doors about 3.5 inchs sqaure, drivers side is at the 9 o'clock position and pass side is at 12 o'clock with the corners meeting (pass side bottom left drivers side top right) i think??? cant remember if this is the position but the corners meet, i had my fingers in there when i accidently changed it to defrost ouch! both doors closed at the same time, and opened at same time, i will check all the hoses and for circulation when she gets home from work, could it be a partially plugged heater core???? also the air door behind the box coming from the area of the blower motor opens and closes fully i did the finger test there also, i want to thank you for your time on this matter, it probably is a resistor like the guy at the dealership said???????? i dont have a clue to where this resistor would be in relation to the drivers side lack of heat, want the dealership name? sharp chevrolet in watertown sd, didnt get the service managers name!!! and finally no critter nests i do know this can be a big problem, as i had a neighbors cat sleeping in my engine compartment on my suburban, i will spare you the gory details

I don't have access to a diagram of the distribution box but that's the core itself above. It might be full of junk in one area that allow the warm area remaining to prefer one side - in that when you tried to stop the air it didn't work that kind of rules that out for now. There was a heater control valve listed in line on heater hose and if there was a sudden drop in temp after that valve towards the firewall it could be a problem itself or is getting incorrect instructions on what to do. Don't think it's that either??

I don't really understand the "resistor" that was suggested for this as I think it's one for fan speed and another to sense temp but shouldn't select one side over another in this single style.

That does lead to a diverter door problem unfortunately.

I'm a bit stumped on what to suggest for you now - gotta save that divorce at least

If the guys here don't have any ideas I'll suggest you come visit us at ACsource.com - forums as many folks are from the hot SouthWest US and these cars last longer there with no rust and would have more techs that have torn apart the distribution boxes - for me exactly none on this body Caddy!

Just curious - is air flow good in general? Any comments made when blower was replaced? One last one - is there a cabin filter for this car? If so check that out right away,

T
Tom Greenleaf - MetroWest Boston - USA
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http://www.autoacsystems.com/tomgreenleaf/

That link should get you right to the forums at ACsource if you want to try there....


http://acsource.net/...644d7d8eeeb77edc058a

T
Tom Greenleaf - MetroWest Boston - USA
_________________________________________

http://www.autoacsystems.com/tomgreenleaf/