does defroster run a/c compressor?

[sgarlic]

close this .. accident.

Nevermind.. answered this one already.. close this plz!

 

[2k2fourpointsix]

When I turn the defroster in my '04 on it runs the fan and drives like the A/C is on.. does anyone know the reason this happens?

the ac is not on, but the ac compressor cycles on and off periodically to keep the seals/bearing lubricated. The main reason that causes the compressors to fail is when they dont get used in the winter months. Most other newer cars are like this also.

 

[Marks5.0!]

yes its on, its only not on when your on vent floor and off

 

[billyfe390]

the ac is not on, but the ac compressor cycles on and off periodically to keep the seals/bearing lubricated. The main reason that causes the compressors to fail is when they dont get used in the winter months. Most other newer cars are like this also.

The defrost is the same as the normal airc onditioning routed to the windshield vents so the compressor runs the same as if the A/C was on. The difference is it will cycle faster because when its cold out the pressures in the system are lower and some systems have an ambient pressure switch that turns it off at a certain outside temp. The reason the compressors fail when the defrost is used alot is because the oil that lubes the compressor is circulated by pressure and the lower the pressure the less oil it gets. If you never use it it wont go bad.

 

[GT-03]

I thought the defogger used the A/C to first dehumidify the air, then the heater core is used to heat the air. The result is dry hot air being blow at the windshield.

I know on my Civic, which has a separate button for the A/C compressor, does a rather lousy job clearing the windshield in defog mode with the A/C off, but quickly clears the windshield if I then turn the A/C on.

 

[billyfe390]

I thought the defogger used the A/C to first dehumidify the air, then the heater core is used to heat the air. The result is dry hot air being blow at the windshield.

I know on my Civic, which has a separate button for the A/C compressor, does a rather lousy job clearing the windshield in defog mode with the A/C off, but quickly clears the windshield if I then turn the A/C on.

Yes thats exactly what it does.

 

[Mustang5L5]

I thought the defogger used the A/C to first dehumidify the air, then the heater core is used to heat the air. The result is dry hot air being blow at the windshield.

I know on my Civic, which has a separate button for the A/C compressor, does a rather lousy job clearing the windshield in defog mode with the A/C off, but quickly clears the windshield if I then turn the A/C on.

That is the reason why the A/C is used when you put on defrost.


They say to run your A/C in te winter to keep the seals from drying out but if you use your defrost regularly you will be all set.