Need help - My A/C is running even when turned OFF

[pomidor]

I noticed that whenever I turned the heater fan ON to any of the 1 through 4 positions (A/C button is OFF), both rad fans would kick in for a few minutes. After a while they will turn off, and then back on again shortly after that. I touched the cold pipe from the compressor, and discovered it was ice cold. So, something is causing the A/C system to kick in even when it's turned off.

When the A/C kicks in by itself like that, it only cools the air by a bit, I noticed. I do have to actually turn it to ON position for it to blow cold air full blast, so it would seem that even when it does come on by itself, it doesn't come on fully.

For the time being, I took the A/C fuse out. Compressor doesn't kick in anymore, but the both rad fans still do that ON/OFF dance whenever the heater fan is ON.

Couple questions

1: Any clue what's busted that's turning the A/C ON whenever the heater fan is in any of the ON positions.

2: This rad-fan on-off cycle (both of them at the same time), that's related to the A/C coming on by itself, correct? I mean, normally when the AC is off, should both fans kick in like that (to cool the coolant in the radiator), or does normally only one of them kick in?

I don't get any CEL

 

[Protephile]

Where is your Vent Set? If Defrost or Defrost/Floor your compressor will run...just in case you didn't already know that.

 

[HighSpeed]

^what I was thinking

 

[pomidor]

Where is your Vent Set? If Defrost or Defrost/Floor your compressor will run...just in case you didn't already know that.

^what I was thinking

Hmm... Interesting.

My Vent Mode is usually set to Defrost or Defrost-Floor.

After reading your question/comment, I put the A/C fuse back in the fuse box, and I tested the system some more. I am getting the behaviour that Pretophile mentioned, almost.

BTW, no, I did not know that compressor kicks in even if A/C button is OFF.

My further test results (Note that A/C button is ALWAYS OFF):

The compressor and both rad fans come ON if both the heater(console)-fan dial is ON (1 through 4 speed setting) and I'm in Defrost, Defrost-Floor or Floor (Floor only).

While the heater-fan is ON, the "compressor+rad-fans" will NOT kick in if I'm in the Vent or Vent-Floor mode.

If the heater fan is OFF (fan position "0"), the "compressor+rad-fans" do not come ON regardless of the vent-direction setting.

This is pretty much what Pretophile said, except that I'm adding the "Floor" fan mode to the equation of the compressor kicking in when console fan is ON.

Compressor kicking in when not in A/C mode uses(wastes) power unnecessarily. Is this behaviour really normal? If so, why?

BTW, it makes no difference if my heater setting is on COLD or HOT, above results are the same

 

[Dermen]

It is normal. Having the AC on can help defrost the windows, but it isn't always required. Not sure why it is on floor, maybe to help dry the carpet in the winter? There is a mod you can do to make it only come on when the button is pressed. It is pretty easy, you just cut a trace on the control PCB. How-to is here

 

[pomidor]

It is normal. Having the AC on can help defrost the windows, but it isn't always required. Not sure why it is on floor, maybe to help dry the carpet in the winter? There is a mod you can do to make it only come on when the button is pressed. It is pretty easy, you just cut a trace on the control PCB. How-to is here

Excellent. I'll definitely be doing this mod