It's a bad resistor pack, for low and medium power goes threw this resistor pack but for high power goes straight in, the part to fix this is inexpensive. It will not cause any problem to run it like this for any amount of time, just it will not have the lower speeds. It will hardly effect gas mileage at all, the alternator generates the electricity to run it, but we're talking less than 2 horsepower to run the alternator, so really carrying another passenger would use more fuel than running the fan on high.
Hi Mary W,
We are sorry to hear that you are having this concern with your A/C. I understand that you are seeking the opinions of your fellow forum members, however, if you need any assistance reaching out to your dealership, we are always here to help.
All the best,
Andraya R.
GM Customer Care
http://ricksfreeautorepairadvice.com/blo...
Running in high uses more fuel, get it looked at.
I have a 2009 HHR and I noticed that my a/c will only run on high. Should I bring it in to the shop to have it looked at or can let it function this was for an extended time?
