Ok you savy hhr owners, I need help. My Temperature guage works half the time, some days it will work, other days not at all. During its "temper tantrums" my air conditioner will not get cold or my heat won't get hot?! Any ideas on what's wrong with it? Cheap easy fix preferred, of course.

 

Thermostat...

 

Welcome

Yes. Thermostat. Your car has the classic symptoms of a HHR that needs to have it replaced. You should also replace the Dexcool (antifreeze) while you're at it. Dexcool should be replaced every 5 years. At 11 years, your car is probably due it's 2nd change.

FYI. I'll bet that your Check Engine Light (CEL) may be on ? If so, it's most likely because of the thermostat. If you pull the CEL codes it would show a P0128 that is for the thermostat.
If that code is there along with the CEL, it will shut off the AC compressor function.

 

Welcome to the site, yes X3 , and install a proper AC Delco 131-158 thermostat and fresh Dexcool.

Here’s a how to

https://www.chevyhhr.net/forums/how-...l-p0128-24493/

 

Classic as others have said. I have my new thermostat waiting to go in when my Original (220500 miles) gives up. I have posted before about this happening, on only two occasion here in Florida. It only happened after a cold start on the coldest day in winter here. This year, I discovered that I had made the mistake of putting the heat on and the air on recirculate, causing the cooling fan to come on, leading me to believe that the combination was robbing the engine of too much heat. This winter we saw the lowest temps yet (21 degrees F at the lowest) and Gregg warmed up nicely and didn't have a problem staying at temp. Because of this, I am waiting for the inevitable. Not something that everyone here will agree with but hey, its worked for me for three years so far. If I lived in a colder climate absolutely would have needed to change it by now.

 

The reason it is intermittent is that the computer wants the coolant to reach 180F in a certain amount of minutes; if the ambient temp is high it may get there quicker than when the ambient is cold.

DexCool, the coolant that you should be using has a life of 5 years. If yours has never been changed, do it now.

 

It was changed two years ago. Back then, I asked if they might be able to change the thermostat out of good faith while doing the flush, but they said I should change it myself then bring it in, or they would have to charge me something like 200 dollars to do it! I know how easy it is to do, but its not an imminent failure sort of thing so I am not bothered. It was fine these past couple weeks where the temps were in the 20's and 30's.

In OP's situation though I would just go ahead and take care of it.