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the heater control valve it stuck closed for some reason. Check for a broken vacume line between the heater control to the valve. With the engine running check for a good vacume at the valve with a vacume gauge it should be close to the same reading as the engine vacume. If all is good then the valve is bad GRUNGE BUILD UP ON EVEAPORATOR (CAUSED BY LEAK) AND BLOCKS INCOMING AIR TO HEATER CORE AS IT IS IN FRONT OF IT. YOU WILL HAVE TO PULL THE EVAPORATER TO CHECK. I KNOW OF 2 INSTANCES OF THIS ALREADY INCLUDING ME ; ) GOOD LUCK. There is a seal that sits behind the heater core and fire wall where the hoses connect to the heater core. You can get an air leak there and cool air will be produced by your heating system. To check: with blower running squeeze your hand down by the heater hoses in the engine compartment. If you feel air coming from the blower motor then you will need to seal the leak. you also have a seal that is on the inner cover to the heater box that covers the heater core. That can cause some air leaks also.
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Why would the coolant light come on and the heater blow cold air in a 1985 Cadillac Deville 4.1 even after you tried replacing the thermostat and flushing the radiator?
Heater core (radiator) needs to be cleaned or changed
How do you stop Chevy lumina 95 from runnuing hot?
Replace the coolant, thermostat, turn off the A/c, in emergencies drive with the heater on, increase the air flow through the radiator, have your radiator checked for blockage.
After replacing new heater core and connection all door valves you still have no heat?
Your thermostat might be stuck open. Does the radiator cap get hot after running the engine for 10-15 minutes? If not, replace the thermostat.
After changing the thermostat you still get no heat in your 1997 lumina?
could be several things. have you tried replacing the heater core. if not that, call a mechanic. you probably won't be able to fix it unless you know what you are doing.
Why does my truck overheat and then when I set the heater to defrost it cools down?
Check the thermostat or the radiator. The thermostat could be sticking or the radiator could be plugged.
What happened to a 1992 Chevy Lumina if it ran hot and all the antifreeze drained out?
Maybe a stuck thermostat, or a broken radiator/heater hose. Sometimes the radiator itself blows a seam. Water pump seal, blown head gasket, etc.
Where is the heater core temperature thermostat?
The temperature of the coolant entering the heater core is controlled by the engine thermostat. The engine coolant thermostat is generally located at the engine end of the upper radiator hose.
1993 Chevy Lumina heater not blowing warm air?
Change your thermostat. Mine had the same problem and it was stuck open.
Is the thermostat the problem when my 1998 Pontiac transport overheats and the top radiator hose isn''t getting hot and the heater blows cold air?
It could be the thermostat. Open up the radiator cap when it is hot and see if the water is flowing in the radiator. If it is not then it may be a thermostat.
Heater has mind of its own goes hot then cold and hot occaisionally. flushed system.new thermostat.radiator.blender door actuator mechanic clueless.still problem. could be heater control itself?
the heater control has a thermostat for the heater only. that thermostat needs replacing
Why should your heater fan be off when you burp your radiator?
It will take a little longer for the cooling system thermostat to open up if the heater fan is on. The heater fan and heater core act like a small radiator and disperses heat energy when in operation.
What would cause cold air to blow when the heat is on in your 1989 Dodge Dynasty even after replacing the radiator and thermostat?
most likely you dont have enough coolant to reach heater core. make sure your full
