I know in my moms minivan the defroster kicks on the A/C compressor, but on my SS im not sure, does anyone know?

 

Yes

 

Thats what I was afraid of, I dont understand why it does thou, cars that dont have ac obviously dont do this, so what advantages does having the a/c kick on if the defroster is being used, and why not make it blue like the rest of the A/C display

 

The AC dries the air,making the windows defrost quicker.

 

This also acts as a lubricating cycle in the winter so that for 4 or 5 months the compressor isn't sitting there gelling up.

 

It's only been this way for the last...oh...30 years or so.

 

Anyway I could wire a relay in to make it so it dosnt kick on when I turn on the defroster?

 

I don't know how the switch is physically made, but you would have to disable it in there. Disabling the a/c request wire from the switch to the pcm would disable it for regular running of the a/c as well.

Is there some special reason why you want to disable the compressor when in defrost?

 

An easy test, would be to disconnect the pressure switch at the rail to the cainster (right word?), to spoof the system into thinking there is no pressure, thus the compressor wouldn't come on.

An easy test... does it work?

 

I'm sure that will work

 

...but like I said, the a/c will not work in any position. Heck, if you just want to disable it, just pull the connector off the compressor.

I thought he just wanted it off during defrost.

 

I want to do it because I like to drive around w/ the defroster on because my windows like to fog up alot because on long island im basically surrounded by water. My gas mileage is already in the gutter, so I'm looking for ways to help it out, even if its just a slight amount.
Im thinking take a relay, and run it inline with one of the wires attached to the compressor, I'll always leave it in the off position, and on the one day of the year that I might decide to run the ac ill just flip it on.

 

I see, though I would think that the compressor coming on would be especially helpful in that climate where there is so much moisture.

It would be better for you to disable the a/c request from the switch to the pcm, though. Once the pcm sees the request for a/c, it is going to raise the rpms to compensate for the compressor being engaged. If you disable the compressor with a switch, you might be annoyed with higher rpms. You also will get some diagnostic trouble codes if you put anything in between the pcm and any sensors or the compressor that opens up the circuit.