Air conditioner doesn't turn on - 2004 WRX

[snake2332]

I bought a 2004 WRX recently. Montana weather got hot enough to where I wanted to use the A/C. Well guess what? It didn't turn on. That is, the compressor doesn't come on and the RPMs don't increase by 500. Plus I hear nothing "kick in" and the blowing air never got colder.

I tested the power at the in-cab fuse box; it was good. I tested the power at the power connector on top of the compressor; nothing. I replaced the relay in the under-the-hood fuse box. It was only 10 bucks and I wanted to make sure that it wasn't the cause. Still no compressor turning on and no power at the contact.

I know some (most?) cars' A/C systems have a cut-off switch somewhere on the A/C line that switches the power off if the pressure is too low. Does anyone know where that switch is or how to test it?

I hooked my tactrix cable up and used Enginuity 0.4.1 (www.romraider.com) logger and checked all 4 of the A/C options. I did it at idle. Here are those results:

Air Conditioning Switch: Remained at zero entire time
Air-Con Compressor Signal: Remained at zero entire time
Air-Con Mid Pressure Switch: Remained at zero entire time
Air-Con Lock Signal: Remained at zero entire time

I repeatedly turned the blower on with A/C on and off with temp set to the coldest level. I'm guessing the lock signal would have read 1 if what I believe about the pressure being too low is true.

Can anyone give me some further ideas? I don't think the compressor is dead, at least I really hope it isn't since they are ~$300 new.

Also, in Enginuity logger, is battery voltage of 12.24v bad when the engine is off and the ignition is on? While idling it was 14.08.

[SD_GR]

Wait, does the system have freon for sure?

[snake2332]

I don't actually know. Should a put a glove on and just tap one of the pressure releases on it? I see the red cap is missing (blue cap present labeled "L").

[tom'sti]

You did all that without hooking a simple set of gauges up first?

[snake2332]

Haha, you jerk! Laugh it up, buttercup. I don't have a high-pressure gauge and I thought the air-con lock signal would show a value of 1 if it had no pressure in the line. Am I wrong? Plus it's not like I did "all that". All I did was test 2 connections for power and bought a measly $10 part. Then checked in Enginuity which I was using anyway for other reasons.

[SD_GR]

I don't actually know. Should a put a glove on and just tap one of the pressure releases on it? I see the red cap is missing (blue cap present labeled "L").

There's a H igh and a L ow side. Opening the needle valve (like deflating a bicycle tyre) with something like a screwdriver end might give you a crude estimate (you'll know if it's empty, not if it's low). The textbook way of doing it is to hook up a gauge set; I believe these can be rented.

thought the air-con lock signal would show a value of 1 if it had no pressure in the line. Am I wrong?

Sorry I don't know.

[snake2332]

I might have to buy a gauge for it, especially if it might be a leaking system. I am taking the car to the local Subaru dealership Monday for a diagnosis.

[SD_GR]

A few years back some cars experienced expansion valve issues also; another thing to keep in mind.