Hey guys, this is only my second post on here so don't be to rough on me, but I've been having some difficulty with my A/C not working. I have the '07 model and I have acquired factory repair manual diagrams for electronics in the A/C system. Aamco ran a test a few days ago for free and told me the freon was low and there is an electrical issue causing the compressor to not run even when the correct amount of freon is in the system. Bypassing the clutch relay activates the clutch, but if you bypass that relay it will not shut off from pushing the button on the dash. Continuously running it could damage the system and end up costing more. My guess is that a sensor or something has gone bad and maybe by bypassing the sensors I can find the issue.
Just wondering if anyone has had luck with fixing this system or if anyone has found a way to fix this. I understand A/C systems can be ridiculously difficult to fix, often a waste of time and money to try and fix yourself. However, it would be stupid to not ask and see if anyone has any ideas. The relay has been replaced and still did not fix it. I have checked for power running to all fuses on both sides of fuse with no issues. The Schrader valve for the low side is leaking and unfortunately for everyone that owns a scion, the only method to replace the valve is by purchasing the whole hose. Does anyone know if you could use a Celica or Camry valve instead? I have tried tapping on the clutch with a pry bar to see if I could get it running (like you would a starter), but the only success I ever have is direct power to the compressor and it will blow out cold air all day.

P.S. There is not very many A/C threads about Scions so hopefully this can help a lot of people and if anyone wants to see the diagrams I have I can post them as needed.

In advance thanks for your input.

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First, Freon (R12) is obsolete and not used anymore.
R134a is what is used now and should not be mistaken for Freon.

The clutch relay is activated by the A/C button.
Bypassing it will remove the A/C button out of the control circuit, which is why it won't shut off.
You replaced the relay and I am assuming it is working now.

You said your low side valve is leaking.
If the A/C system leaks and does not have enough refrigerant, it will not have enough pressure and it will cause the system to fail.
Fail as in no compressor operation and no cold air.
Take it to a shop and have them replace the leaking valve.
You do not need to replace the entire hose.
Any decent shop should have specialty tools to replace A/C valves.
I would also ask the shop to recover the system, put a vacuum and leak check it to verify there are no other leaks.
EDIT: this tool

Also don't tap the clutch (or the starter) too hard with the pry bar.
Both use magnets to operate and a hard enough hit can break the magnet causing permanent parts failure.

 

First I would check all the HVAC fuses. Then I would pick up a recharge can with a gauge and test the system levels. If the system is very low the unit will not kick on. It's a safety feature used to protect the unit itself.

 

Do you have a diagram that shows where the MG/C relay (magnetic clutch relay) is located.
The system has the right refrigerant levels on my 09 tC, but the clutch is not engaging,

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The mag clutch relay is in the upper left corner of the engine bay fuse box.

Toyota part number - 90987 02028
(I left you some more info via private message.)

 

I'm having this same issue may I have the golden egg as well? kind sir

 

Unfortunately, the "diagram" so to speak only points to the box, not the precise locations of fuses and relays. Fortunately, the part number is on the actual relay. You're looking for part number 90987 02028. If you're facing the windshield, the mag clutch relay is in the upper left corner of the fuse box.