Air conditioner goes on with defroster even if its snowing!

Reply Subscribe

Thread Tools

Search this Thread

12-07-2005 | 02:30 AM

#41

Tomas

Admin Emeritus

SL Member

Joined: Jan 2005

Posts: 14,570

From: University Place, WA

Quote:

Originally Posted by no-scion

i have gotten responses stating that you can't turn off the AC with the defroster on. hmmm... i don't seem to have that problem. i have no problem turning it off even with the defroster on.

No, what you turn of is the little green indicator light on the A/C button. If you read the manuals you will find that other things will override your manual selection, and actually run the air conditioning when 'defrost' is selected, for example. The mere absense of the little green light on the button does not mean the A/C is not running - it only means that if it IS running, it was not your manual choice.

That's all that little green light indicates: Your preferences. The system programming overrides that at will.

(Read especially the test procedures in the service manuals.)

The basics:

Green Light ON: The A/C compressor defaults to compressing but this can be overridden by throttle position, engine load, engine temp, and the positions af all the other heating/air conditioning controls. AMOUNT of compression depends on how the controller positions the internal swash plate in the compressor.

Green Light OFF: The A/C compressor defaults to not compressing subject to demands by other heating/air conditioning controls.

Your A/C button is but one input to the controller, and the little green light only indicates what your vote, is. You can be outvoted.

Keep in mind, also, that the compressor shaft is always turning when the engine is running - there is no clutch on it. The controller electrically controls the swash plate of the compressor to vary it's displacement and therefore the amount of compressing it is actually going to do.

Turning off your little green light does not turn off the compressor - it only removes your vote to keep it on.

(The older systems were easier to understand - they were either on or off at the user's choice. That is no longer the case in todays relatively sophisticated vehicles.)

NEXT!

________________
Tom

12-07-2005 | 03:27 AM

#42

tvc15_2000

Thread Starter

Senior Member

SL Member

Joined: Sep 2005

Posts: 104

Thank you for the excellent explanation

Reminds me of the quote
“Who wins the election is not important. What is important is who counts the votes!”

12-07-2005 | 05:51 AM

#43

slngsht

Junior Member

Joined: Dec 2005

Posts: 9

From: Roanoke, VA

Quote:

Originally Posted by jethro_b

Quote:

Originally Posted by mrjon

Quote:

Originally Posted by jethro_b

The compressor doesn't work like a conventional one. It doesn't have a clutch that engages in and out. It turns all the time. The difference is internal. It only "compresses" when it needs to. This is why there isn't much difference when it is working.

Indeed, there is no way to tell from inside whether or not it is running, unless you notice it getting cooler inside.

slngsht: If you suspect that the a/c might not be working, pop the hood and check the little glass window on the air conditioning line. You should see bursts of liquid (compressed refrigerant) moving through there when the a/c is on, and it should diminish once you turn the a/c off.

Here's what you're looking for: (This is on a 2006 xA so your engine compartment may be a little different)

Good pic of what to look for. You could also grab the A/C lines and see if they are cold or warm.

Ah, nice to know, thanks for the info, I was wondering what that little eye was for, as I've never seen them on any other cars.