1992 Cavalier heater problem


Old 12-22-08, 08:37 AM
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Join Date: Dec 2008
Location: Alberta
Posts: 6
1992 Cavalier heater problem

Having problems with my son's 92 Cavalier. The heater blower motor runs, all the heater vent actuators and vents appear to function, but virtually no air flow out the defrost, heater, or vents. I removed cover from heater core and blew compressed air back through the heater core, but has not helped. When I switch to the temperature selector from 'Hot' to "cold' there is a noticeable increase in air flow through out the defrost or vent. Could the heater core be plugged or am I missing something? It's a big job to remove it and can't understand "why" it would be plugged. Is there a filter or something in place ahead of the core? Any advice or ideas would be appreciated. Thanks
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Old 12-22-08, 08:54 AM
Join Date: Jan 2006
Location: Owen Sound Ontario Canada
Posts: 541
The core can get plugged with air.
You blew thru it with air so that would mean that it is not plugged.
After the car has been warmed for a good 20 minutes then carefully feel both heater hoses going into the firewall with the heater on. One hose should be , we shall say hot, and the other hose sould be "warm"
What I would try is to take the hose off and fill the heater core with coolant then hold up the heater hose high and fill the hose with coolan and put it back on real quick not to let air back in. Can be a bit messy but it works for me.
Old 12-22-08, 01:00 PM
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You say the vents actuators appear to work, but have you actually observed them. If they are vacuum controlled, I would be looking for a leaky or disconnected hose.
Old 12-22-08, 05:29 PM
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Join Date: Apr 2008
Location: Oklahoma
Posts: 1,698
leaves, pet hair, dust, virtually any thing could block the heater core from passing air, if you can see the blend door mechanism move then remove the blower motor and check the passage for debris, my daughters grand prix got where it wouldn't blow and the fan was full of leaves due to a hole in the screen intake.

how come common sense isn't so common?
Old 12-23-08, 04:42 AM
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Join Date: Dec 2008
Location: Alberta
Posts: 6
Thanks for the suggestion. That would be much easier than pulling the heater core out to check for the same thing.
Old 12-23-08, 04:46 AM
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Join Date: Dec 2008
Location: Alberta
Posts: 6
Yes, I have observed them working. Had to pull off a couple of covers and stand on my head to do it, but I did verify they are working. A disconnected vacuum line was last year's problem.

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