Hi,
My car blows warm air when press down the AC button. I've done the following actions so far.
1. HVAC self diagnostics:
0:05 Recirculation button blink twice
0:06 AC button light ON (not blinking)
0:11 Mode Control Button (Vent) and Recirculation button lights ON (not blinking)
0:17 AC and Recirculation lights OFF

2. pull out the AC clutch relay. Apply 12V across the two control pins, measure the resistance between the two copper pins shows 0.01 Ohm. Remove the 12V the resistance between the two copper pins is OPEN.
3. Swap the AC clutch relay and the Blower relay, still no cold air.
3. Put back both relays. Disconnect the clutch connector. Turn on Engine and fans. Measure the voltage to the clutch and it is 12V no matter the AC button is pressed down or up.
4. Turn Off the engine. Measure the clutch connector to body ground and it shows OPEN. Also confirm the clutch ground wire is shorted to car battery ground.
5. Plug back the clutch connector and turn on the engine and AC. There is no click sound from the compressor clutch. Confirm the outside plate of the clutch doesn't rotate with the pulley. It shows the ac compressor is not engaged at all.
6. Bought a can of R134a but didn't recharge since the Low pressure is in the red zone when plug the can.
7. Remove the clutch relay. With engine ON (AC OFF) I measured 12V from one of the control pin sockets and 12V from one of the copper pin sockets. Measure the other control pin socket and it shows OPEN to ground. The other copper socket also OPEN to ground. Press down AC(ON), the other copper socket still OPEN to ground. the other control pin socket's reading is not very stable, changing from 20Ohm to 40 Ohm.

It seems that I probably get a bad clutch coil (from step 4). I am not sure if the compressor is fine if I change the clutch. I also feel confused about step 3 since it should be no power to the clutch when AC is OFF. Yet it shows 12V no matter what.
I am kind of stuck and your input is very appreciated.

Regards,
Hexar

 

Moved your thread to the proper place to get some help.

It sounds like the compressor clutch coil is open circuit. The wire to the clutch should not have power when the a/c is off.

The other copper relay pin is a direct connection to the a/c compressor clutch coil. Do you get 12V on that pin?

If you remove the clutch relay, does the compressor clutch wire still have 12V?

 

I don't know why but now the clutch doesn't see 14V when a/c is off. It does see 14V(not 12V) if AC is ON. Talked to a mechanic and he suggested that I change the ac compressor cause it is almost the same price of replacing the clutch.
Thank you very much for your reply.

 

Not sure if you are having a shop do the work or if you are doing the work.

If you are replacing yourself, replacing only the clutch is easier. You don't have to discharge the R-134a if only replacing the clutch. On the 4-cyl, the compressor needs to be unbolted from the bracket, because there is not enough clearance to remove the cltuch plate. The V6 may have enough clearance to pull the clutch plate and make this an even simpler DIY repair.

If you are replacing the entire compressor, you should have the a/c discharged by a shop to recover the R-134a. I recommend replacing all o-rings in the whole system and the schrader valves in the high and low lines to have fresh seals that should hold the R134a charge for many years.

 

if you get power to a/c clutch with a/c on and clutch not engaging another issue could be that the clutch gap is too big i have seen a bunch of those , this is a little tricky but with a/c on if clutch not engaging get some sort of lever see if you can try to pry a/c clutch in , if it engages clutch gas is too big needs to be re shimmed,, if not most likely bad clutch , need to remove and inspect properly

 

Yesterday I picked up my car from the mechanic. The mechanic said the old clutch electrical circuitry was broken. Now the AC works fine. The whole repair cost is about $400, half of which is for the ac compressor (I bought a Denso unit from RockAuto) and half for labor. Given the age and mileage of this car I think it makes more sense to replace the whole AC compressor instead of just the clutch. I also had trouble to find a trustable clutch anyway.
PAhonda, I hope that I read your reply about the o-rings and schrader valves earlier.
Thanks everyone for your input. I appreciate your help and time.