I have a problem with the heat in my 2005 Monte Carlo SS where the heat no longer gets very hot. It’s pretty much now on the cool side (Luke warm)

Also I have now taken notice of the temp gauge remaining on the colder side.

As for the heat, it began last year and seems to me back then I could hear a vacuum noise of some kind when I changed the vent settings from defrost to floor setting, almost as though it was sticking and then became stable, which produced hotter air.
But now I don’t hear it anymore and it just blows luke warm air only.

If it’s a vent problem where the doors are not operating properly do I need to get under the dash to address the problem?

I am thinking about changing the thermostat anyway and replacing it with a 195 degree, does this sound alright?
But I need to get the heater working for my wife.

Thanks in advance for your time.
Uncle Mo

 

My first thought is that your T-stat is hanging open. I would replace that first and see if it solves the problem.

 

i would replace the t-stat and make sure all the air is out of the system after replacing the t-stat

 

Yea thats the Tstat. Mines only luke warm. Guess having a 160* drilled tstat in the winter isnt the best idea.

 

I had the same problem with luke warm heat. I replaced the T-stat and the hot air worked just fine again.

 

I popped a drilled 180* into mine two years ago in January.
When the ambient temp dropped down to about 20* or less at night, the car wouldn't get above 140* even after a half hour of driving. Watching the temps drop down even further when the heater was on, and having cool air blowing from the vents got old fast.
Switched to a non-drilled 180* as soon as it was warm enough to change the t-stat without my hands going numb.

OP: Any luck with the issue?
Newer thermostats are made to stick open when they fail, so that the car won't overheat in the event of a thermostat failure. This isn't always the case when the heater is blowing cold air, but is a cheap fix if so.