Diagnosing AC fault - 2010 my

[Civvy]

Hi,

I am sprucing up a newly acquired, used 2010 Aveo5 that had a few issues. I'm an experienced mechanic, but always eager to get good advice and not re-invent the wheel!

Besides checking brakes, changing fluid, the only minor issues seem to be a stuck/sticking thermostat, TPMS light on, and no A/C engagement when the button is pushed (clutch/compressor does not try to engage). It is a west coast/PNW car w/only ~70k so really very clean. I'm going to swap the thermostat soon and then try to figure out the A/C. Googling the issue did seem to lead me to believe this is a common weak point on these (like the thermostat).

I have been searching a bit and went through the "tech tips" section. I saw a How-to on compressor replacement, but I'm wondering if anyone has experience with the diagnostic tree and common fault points on this system? I have checked the fuses and swapped the relay as a "duh" check. I have not checked hi/lo pressure yet to see if that is blocking it, in case leaks are common.

Any suggestions?

Thank you!

[rhyder7]

Check if the pressure switch is good.

[Civvy]

I am finding lots of recommendations to do that, but no how-to. Any instructions or link? I have been searching for that procedure but no luck.

[WyrTwister]

Check to see if 12 VDC is making its way to the compressor clutch coil . If so , check ti see if the coil is " open " , with an ohm meter . If good , check the clutch plate gap .

Wyr
God bless

[gatorjoe]

just had same problem and I replaced the ac clutch by itself and I'm back in business and cooling great. repair cost $60.00 and i did the repair in 4 hours.

[MichiganMadMan]

My experience is that the cooling fan low speed circuit is dodgy on these, causing it to overheat and "boil" the refrigerant when the fan quits blowing. This destroys the compressor in the process. I rigged up a way to bypass the ECM and power the fan on low speed that I turn on whenever I'm using A/C and it's been working for two years.
My compressor was shot and I ended up replacing the expansion valve (not necessary, I thought it was the source of the problem) and the condenser to be thorough. What it really needed was a new compressor and a fan bypass.

[gatorjoe]

...remove nut, install rented tool from parts store, remove rusted ac plate, install new plate and gap it. It works great and parts under $60 at amazon. I have a 2005 aveo.