TXMAG

Recently picked up this hatch for my little sister and have finally decided to turn my attention to the AC system.

I just installed a new pulley and compressor and recharged the AC system this afternoon. I added the recommended amount of R134A and the pressure readings are good (I think) with about 35psi on the low side and 200psi on the high side. The AC blows nice and cool now.

The problem is that the compressor clutch will not disengage if the AC is turned on. To clarify, it doesn't cycle and this is probably what killed the previous compressor - A constantly running clutch. The previous compressor was totally locked up and would not spin which is why I got a new one.

When I press the AC button the clutch and condenser fan kick on. When I press it again they turn off as expected. All underhood and underdash fuses and relays appear to be working correctly. I even swapped a few underhood relays around and noted the same behavior. When I remove the AC compressor clutch relay from the underhood fuse box, the clutch does not engage with the AC on or off. Again, expected behavior.

I assume there is probably a short somewhere and am hoping someone can point me in the right direction. I'd hate to break this compressor over something stupid. Voltmeter is in hand and ready to go.

Thanks!

Former User

Test the A/C thermostat (plugs into the evaporator) behind the glove box.

TXMAG

Thanks Ron, but what exactly do you want me to test for? A voltage reading of some sort?

Former User

What you are saying is that both the fan and clutch stay on, right? The fan never turns off either, right? If so:

Unplug the 3P connector. With the A/C and blower on, does the fan fail to run and the clutch fail to engage? If you now short the Blu/Wht and Blu/Red wires in the unplug connector, does the fan run, the clutch engage, and the A/C blow cold as long as the two wires are shorted? If so, replace the thermostat.

TXMAG

This was exactly it Ron. With the 3P connector unplugged neither the AC compressor clutch or condenser fan worked. As soon as I shorted the Blu/Wht and Blue/Red wires together the fan and clutch engaged.

Will get a new thermostat on order!

Thanks for the quick response and great advice.