maxwku

My 1992 Toyota 4Runner AC is not working. Here is what I have checked and observed so far. Any advice would be very helpful.

1. AC clutch engaged when wired directly from battery.
2. Have Freon in system and plenty of it.
3. Green light on, when AC button pressed.
4. Confirmed 13 volts at AC button inside car.
4. Condenser cooling fan running strong.
5. I checked the source wire from the wire harness to the AC compression and only reading 0.30 Volts. I checked first by grounding my multimeter against the AC compressor. Then I grounded the multimeter at the battery. Both ways gave me 0.3 Volts.

So I'm getting 13 Volts to the AC button, but I'm not getting voltage at the AC compressor. Anyone have any ideas based on what I have described. Anything I'm missing.

Charchee

Too much head pressure in the system will cut out the compressor as a safety measure. You could have some kind of obstruction in the high side or just too much freon in it. What are your gauges reading?

If you don't have access to manifold gauges, find your pressure switches and troubleshoot them. In my line of work, I have to troubleshoot ac's almost every day and when I get your symptoms, I usually find that the system is either high or low on freon and the pressure switches have cut out the compressor in order to protect it. Either way, go ahead and figure out what the root cause is and fix it. Letting freon out or putting more in just to get it going normally leads to $$$ later.

maxwku

Charchee, after working on it all day I have traced the problem back to the A/C Cut-Off Relay. I tested the relay and found it would not engage. I shorted the pin's (jumped the pins) and got 13 volts to the compressor. With the clutch locked up, I got a reading of 45psi on the low end and ice cold air coming out.

I will add that when the compressor kicked in and ran for a minute I got a pretty nice puddle of antifreeze from somewhere. I cleaned it all up and tried to let the 4runner run for another couple of minutes to see if I can see where the leak is coming from, but nothing more came out. I don't know what that's about or even if it's related.

Charchee

Glad you got it figured out. That low side reading is a little high for my liking but not out of this world. I would check the specs on your ac system. If you're 10 pounds too high or more, I would let a little out.

Too bad about the coolant leak or whatever that was. I always hate finding another problem just as I get one fixed.

maxwku

I will try to look up specs to see what the proper readings should be, I definitely don't want to mess anything up with the ac system right as I fix it.

I know man...it's a bummer.

Thanks!