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'98 Civic A/C Normally blows hot air but occasionally cold

MikeP on Mon June 09, 2008 12:54 PM User is offline

Year: 98
Make: Honda
Model: Civic EX

Near the end of the last A/C season my '98 Civic EX would began to occasionally blow hot air instead of cool. It generally would start blowing cold air and eventually start blowing hot. It eventually got to the point where all it did was blow hot air. Then on my way to take it to the dealer to have it checked it out of the blue started blowing cold again. It did this for a couple days but has now gone back to blowing nothing but hot air. Any ideas?

mk378 on Mon June 09, 2008 1:12 PM User is offline

Could be the clutch gap. When you push the A/C button the condenser fan should start and the idle speed should increase. Then the compressor engages. If it does the first two things but not the compressor, it is trying to run but the clutch gap could be too wide. Ordinarily you check that by seeing if tapping on the clutch plate will make it snap in. This is difficult to do safely on a Civic because of the tight clearance around the compressor.

MikeP on Mon June 09, 2008 3:24 PM User is offline

Update. When I got into the car today it was blowing hot air again. I'm not sure why I thought to try this other than I knew it could still blow cold but I adjusted the thermostat all the way to hot and then all the way back to cold and it started to blow cold air again. After about 2 mins it wasn't blowing as cold but then would gradually blow cold again. After stopping and running some errands and getting back into the car it wasn't blowing very cold but again by sliding the thermostat all the way to hot and back to cold it seemed to jumpstart the a/c blowing cold again. Any thoughts?

mk378 on Mon June 09, 2008 3:33 PM User is offline

While it is blowing hot, you need to check under the hood and see if the compressor is engaged or not. That will tell a lot. When the compressor is engaged the flat plate on the front of the pulley will be spinning. When not it will be sitting still even though the pulley is turning with the engine.

Air flows thru the A/C first and then the heater. If you have the dial all the way on cold the heater should be shut down. The water valve that turns off the water to the heater when the control is on cold may not be closing all the time. The heater can easily overpower the A/C and make the air hot again.

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