Hot air flow through vents when fan off

OK, so let me get this straight, you're saying that while switched to defrost the compressor turns on and it becomes cooler while the A/C is running (compressor and all) but you can also USE the A/C by pressing the button and then the air becomes much colder, because the A/C is now on even more?

I'd be interested to see what the differences are in the settings because I've run the defrost and never heard the compressor kick on or have the water drip under the parked truck like when the A/C is on (lit button on)

Seems like you know your stuff so are there two different type of A/C settings/compressor systems vehicles have?

Rob

 

No, what I'm saying is, when you have the selector in the Defrost/Floor or Defrost position, and the fan is set to 1, 2, 3, or 4, then the A/C compressor is going to kick on. It makes no difference if you have the A/C button pressed or not, the A/C compressor will be on, there is no way to disable this without getting into the wiring.

See for yourself, set your selector to Defrost, Temp can be hot/cold as this makes no difference.

Now watch your RPMs, and switch the Fan Speed to 1, 2, 3, or 4 and you will see/feel the RPMs rise and A/C compressor clutch engage.

Having the A/C on dries the air, it can be dry COLD air or dry HOT air, makes no difference if you use the DEFROST selection with the temp all the way cold or hot. In the winter, I'm sure you would prefer the HOT.

PB

 

Will do! Thanks for the info, I'm going to check this out in my Tacoma when I get off of work as I've always been under a different impression as to how the A/C works. I thought it was only on when lit up. Coolio.

Rob

 

Absolutely correct!

 

Um, no, it doesn't. The intake for the HVAC is at the base of the windshield, below the wipers. Vehicles have been designed that way for quite some time so that in the event of an exhaust manifold leak, the system won't pull in carbon monoxide. The warm air most likely is from some small amount of air passing through the heater core; the door that closes it off may not be sealing completely.