does fan door motorized or on a vaccuum line when you switch from AC to defrost?
Start driving with your air conditioning on defrost, the AC will defog the windshield but you need to be moving.
The defrost function simply directs air over the inside of you windshield. It's temperature is controlled by the temperature dial on your environmental controls.
It only stays on when the air flow is turned to defrost. It does this because the air condition has a dryer on it that dries the air which defrosts the windshield better.
ihave a 1986 chevette that when i turn defrost on it blows out heat and when i put heater on it blows out only cold air? ihave a 1986 chevette that when i turn defrost on it blows out heat and when i put heater on it blows out only cold air?
Check the vacuum supply from the engine. If it is disconnected or cracked the system will default to defrost only.
If it only does this after a rain, chances are you have a leaking windshield. Or the aircond. drain is clogged, even if you are only using the defrost with heat the air-cond. runs with the defrost.
A/C compressor will operate if windshield defroster is activated--this works as a dehumidifier to help with defrost process. Normally if ambient temperature is over 45 degrees Fahrenheit.
On my 1995 Ford Explorer when the defrost position is selected , and the temperature knob is set in the red area to get heated air to defrost the windshield , the A/C compressor will cycle on and off to help dehumidify the air, but the compressor ONLY cycles on and off in the DEFROST POSITION ( sorry if I'm misinterpretting your question )
With many vehicles, if the defrost mode is on, the ac will continue to run. This helps to clear the inside windshield from moisture.
yes, however, if the ac does not work then you will be unable to blow cold air on a hot steamy windshield to defog it.
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