munden

I apologize if this is a repost -- but I searched a few pages and didnt see anything like this...

So here's what happens... while I'm driving (city or highway, doesn't seem to matter) AC on fullblast as usual... suddenly my usually awesome AC starts blowing warm air. At the exact same time, my gauge on the left flatlines and the coolant section of my readout goes to "COOLANT ---ºF" as though it's no longer registering. Sometimes it stays like that for half the day, and sometimes it's back to normal as I'm driving. SO FAR I have yet to see anything that triggers this or the cause that makes it go to back to normal. Sound familiar to anyone?

donbrew

You need a new coolant tstat, maybe a temp sensor, most likely new DexCool if it's more than 3years or 150K miles old.

At least check your coolant level.

firemangeorge

Most likely you have a engine cooling system thermostat that is going bad. The cars ECM will shut down the AC function when it detects a cooling system problem.
Can't believe you didn't find anything with a search. Thermostats used to be one of our favorite topics.

whopper

Here is the How-to on replacing the thermostat - https://www.chevyhhr.net/forums/how-...l-p0128-24493/

To add to the previous comments, the Check Engine Light will SOMETIMES light up (depending on the condition) and give a code of P0128 which means the engine has taken too long to warm up. And that is caused most likely by the thermostat being jammed open by the deteriorated gasket that surrounds the movable valve in the thermostat itself.

But check the coolant level - and if you replace the thermostat, try and get a GM one, as it seems they have a revised thermostat that does not use the rubber gasket.

munden

Awesome - thanks for all the helpful input and the HowTo. I appreciate it!

ChevroletCustomerService

We're sorry to hear of your A/C concern, munden. Please let us know if our help is needed. We can definitely understand how frustrating this might be and we want to apologize for this inconvenience. Please private message us your VIN, mileage and contact information if we can look further into this matter for you.

Kristen A.
Chevrolet Customer Care

oldracer

As noted in the earlier post, I would suspect the thermostat and/or the temp sensor. I had the same issue as you are having and decided to replace both since "I was in there". My thermostat had some loose rubber pieces in it so it was probably sticking and both were very easy to do with parts from RockAuto.com.

As a side note, when the outside temp is 100 degrees or so, every now and then it seems the air temp coming out the vents warms up and I have found if I slow the fan speed a click or two, within a few seconds the air cools right off again. I can then run the fan on high.

Doc brown

Funny this is posted. I just went through this recently. Replaced thermostat, issue resolved. Not too expensive and about 20 minutes of work.

munden

Well as WHOPPER mentioned might happen above, my CHECK ENGINE light decided to make an appearance this morning on the way in to work.

Thank you for all of the great feedback. Looks like there's some wrench time in my near future.

donbrew

What's the code? Just because it lit doesn't mean squat. There are somewhere in the neighborhood of thousands of codes that could cause a CEL.