Onthepath

Sorry for another A/C thread. I feel like I’ve read a hundred threads on the topic and I’m frankly on information overload.

I’m very new to working on my car but I need to get this resolved on my own, even though I have no mechanical expertise. Taking it to a shop is not an option, so I’m resigned to learn as I go. I desperately need some troubleshooting guidance for m greater minds than mine.

Purchased my 2009 HHR a few months back. Soon after, the check engine light came on and it threw the P0128 code. The guy at the parts store said I was really low on coolant. He added some for me and said if the light didn’t come off, I should change the thermostat or the temp sensor. The light came off and all was well. Then a few weeks later, AC stopped blowing cold. Light came on again for one day and again turned off. Air still didn’t work though. Temperatures seemed the same to me.

I got to reading here and figured I needed to change the thermostat. I ordered what I thought was the correct thermostat on eBay, it was AC Delco branded and the box had some official looking GM branding. I’ve seen some mention that it’s sometimes old bad stock on eBay though and I only paid about $40 for it. So maybe it’s the wrong one.

I paid someone to replace it for me. Nothing has changed though. AC is still hot. The coolant temp seems to run about the same as before. Around 192ish at highway speeds and about 205ish in town.

Is there a way to know if the new thermostat is working correctly? The old one did have a very broken black seal.

I figure if I take this step by step, and learn as I go, I’ll eventually figure out what I need to repair/replace. Plus I’ll know my car better. Necessity is the mother of invention after all lol

Any thoughts or suggestions on what I should try next? Thanks in advance.

- Kari

donbrew

Look at the digital temp readout on the dashboard, not the analog gauge. Running temp should be between 180F and 190ishF.
The reason the AC is not working is the P0128. That means that the computer is being told that the temp is not rising to 180F fast enough or is running below 180F. It is intermittent because if the ambient temp is high it might warm up quick enough. Could be either the t-stat stuck open or a faulty temp sensor. If you are getting a digital temp the sensor is working.
I hope you didn't pay much for somebody to unscrew 2 bolts. Some mechanics are idiots and have been known to screw the gasket up. The rim of the t-stat should be in the groove of the gasket, old fashioned gaskets wet either on top of or under the rim.
Check the coolant level under the pressure cap (COLD), it should be full. The over flow tank should be about a quarter full when cold, too much is as bad as not enough there is a mark on =he bottle but it is hard to see.
Was the part number 131-158?
Owner Manual and shop manual link in my sig.

jimvw

Try resetting the error codes with a scanner. If the digital temp says ---F than the p0128 is still in there and needs to be reset/cleared.

greg8453

The problem you are having with your AC is not related to the thermostat. They are separate issues.

Oldblue

But if the thermostat sets the P0128 code the AC is disabled .

firemangeorge

This ^^^^^

PulpFriction

There's a good chance that the guy putting a thermostat in for you didn't get all the air out of the system.

If you think you can't afford a good mechanic, try the cost of a ruined engine because you didn't take it to a good mechanic.

You do have the option of educating yourself by doing some more searching here. Look for discussion about "burping" the cooling system to get all the air out.

Oldblue

https://www.chevyhhr.net/forums/how-...-system-60614/


Excuse me.