Thread: Air Con problem
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Old May 27, 2012 | 02:55 PM
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onehundred80
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From: Ontario
Default Re: Air Con problem
Originally Posted by DJ Dax
Thank you guys ..I will check the fuses and the valve...I hope its something simple....
The problem may lie in the coolant circulation valve not working for some reason. This would allow the flow of hot engine coolant through the heater core. This can be checked simply by running the air conditioner when the engine is cold. Cold air that progressively gets warmer as the car warms up would prove the point.

The air passes through the heater core and the evaporator (cooling core) the air does not bypass one or the other by means of a baffle.
If the heater coolant is not stopped or restricted sufficiently then the air will be warm. The air first passes the evaporator and is cooled it then goes through the heater core and if the heater core is warm it will slightly warm the air up again. If the coolant has not been restricted at all then the air will be warmed up quite a bit. Remember the heater core can warm up cold winter air that is colder than the air conditioner can achieve.
Using the two wheels on the controls dials down the amount of coolant passing through the heater core, the temperature of the evaporator remains the same. this means the air hits a cold evaporator and then a heater core that could be cold because no engine coolant is passing through it or hot because all possible engine coolant is passing through it and all temperatures in between. The resulting blend of air goes from warm to cold.

The air passes through the evaporator first so it can dehumidify moist air before it hits your windshield in the cooler months when demist is selected on the dial. Selecting demist will start the air conditioner if it is not too cold out. If it is too cold out then the air is not laden with moisture anyway.

The Repair Manual has good diagrams of the system which is common to most cars.
 
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