Thread: Heater Goes Full Hot Only on Driver's Side
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Old Jun 6, 2015 | 06:52 PM
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onehundred80
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From: Ontario
Default Re: Heater Goes Full Hot Only on Driver's Side
Originally Posted by Frankenmerc
I'm looking for someone who actually KNOWS what they are talking about.
Please do not bother answering if you want to tell me I need a new Heater/Air Condition Controller - the module that mounts on the center console. I now own 3 of them.


The PROBLEM:


The driver's side temperature goes full hot only on the driver's side seemingly at random.
This happens regardless of the set temperature and regardless of whether or not the air conditioner is being used. It will happen when I want heat, when I want A/C, or when all I want is ventilation air.
If I turn off the A/C and the fan and wait 20 minutes to an hour, I can then restart everything and it all seems to work normally again, sometimes for days. Then the failure repeats.


I am now up to 4 garages that swear it is the controller but I no longer believe them. Three controllers and you're OUT! Does anyone have any other suggestions? I have not noticed any pattern as to when this problem occurs. It seems to be completely random. I have been "tolerating" it for 5 months now.
The two valves under the hood control the heat that passes through the heater core, if one jams then no control will move the valve. These valves are side by side and near the battery.
With the heater control in the OFF position check the temperature of the hoses at the front of the valves, they should be cool or cooling down. The valves stop or hinder the coolant flow out of the heater cores. There are two cores, one for the driver and one for the passenger. These valves are normally open, so will supply hot air, one could be stuck in the open position and not moving to the closed position when signaled to do so.
I am a bit vague on the total system but I think .....
Air passes over both the AC and the heater cores, the heater core should cool down when the valve shuts and slowly allow the AC to do its work. That's if the heater was on prior to switching on the AC.
There is a diverter flap and I have forgotten what it does, I think it supplies air that has not passed over the AC and heater cores.
I should look at the Service Manual, I assume you have (?).
 
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