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Tech in Chit Chat, need help with AC on my subaru outback.

Toyoda

Well-known member
Joined
May 19, 2020
Member Number
200
Messages
57
2004 subi outback, 4 cyl with manual ac (auto is set the temp and it stays).
I pulled the system into vacuum, 800 microns (29.8 inhg). It held for a day.
Used a Robinair machine to put 24 ounces in, I still have pressure.

System will not run. I have voltage through the pressure switch (tried jumping as well) but it won't kick the system on. I have power on the ac relay and both fan relays.
If I jump the clutch the system will run and make cold air, I have an electrical issue somewhere.
I can't find the ac module to check for power in and out, but at this point I am guessing that is the issue. I believe I have power where I should but something in the control side isn't working.

If I can't figure out the issue can I add a new switch/relay to put power on the fan relays and ac relay? This would power everything up but wouldn't kick up the idle. The fans should keep the low side pressure down while idling.
 
Toyoda said:
If I can't figure out the issue can I add a new switch/relay to put power on the fan relays and ac relay? This would power everything up but wouldn't kick up the idle. The fans should keep the low side pressure down while idling.
Click to expand...

I have used a switch and relay a few times when working on auto a/c system with electrical issues, it worked fine everytime.
 
awesome. I figured as long as the fans were on it would work but wanted to double check, I can't afford to rebuild the system.
 
Toyoda said:
awesome. I figured as long as the fans were on it would work but wanted to double check, I can't afford to rebuild the system.
Click to expand...

On my most recent fix, my 1999 Lexus with random ECU modules issues.

I ran a switch and relay to the switched hot side on the relay block under the hood.

This turns the a/c compressor clutch on as well as the a/c fans.
 
Sounds like it is the auto switch that is being the problem. Go to the junkyard, pull the control module (the whole thing) and relplace yours, see if that fixes it.
 
Thank you.
Is the ac control module the actual climate control group in the center of the dash? That would explain why I can't find a control module under the dash.
 
Toyoda said:
Thank you.
Is the ac control module the actual climate control group in the center of the dash? That would explain why I can't find a control module under the dash.
Click to expand...

yes at least in the Forester and STI they are all in one unit. Not 100% sure on your outback but it should be. It should be all one unit together, plug and play.
 
Try swapping out the clutch relay. For a few years denso made some shit ass relays and I was changing them out on a daily basis for a while.
 
I made sure all the relays were working, I was hoping for an easy problem.
 
Toyoda said:
I made sure all the relays were working, I was hoping for an easy problem.
Click to expand...

How did you? They still work and pass some current, but not enough to energize the magnet. So just testing it with a test light, power probe or meter won't work.
 
I stuck them in the foglight slot. Same relay part number for all relays in the main fuse box. This gave me visual verification the relay works.
 
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