Alright, so I have a 97 Carlo and I'm not sure exactly what is wrong with the heat. It used to work off and on, like it would get hot and stay like that for a bit, then get cold again. Recently, it won't even get hot and it just blows kinda cold air. I had put antifreeze in it and it seemed to fix it, but only for a little bit. I don't know if this is of any significance but the past week or two, every time I start my car and go places, the temperature gauges slowly goes all the way over to the red side, then it slowly goes back to the middle and acts normal. I'm not sure what is wrong, but I need some heat in my car soon due to the snow approaching.

Any help would be greatly appreciated! Thanks!

 

you need to get your cooling system checked out. it isn't normal for your temperature to be close to the red. normally the temp gauge should sit about or just under the middle.

since you had to add coolent, you may have a leak. check for leaks, also your tstat could be stuck open allowing coolent to continuously flow through the radiator and keeping engine temperatures cooler.

main thing is check for leaks, especially around your water pump, upper and lower radiator hoses, and around intake gaskets. if you find something, repair it, or get it repaired and completely flush your cooling system to get fresh coolent in flowing.

 

I'm going to assume you have air pockets in your cooling system. I would get it flushed and change the thermostat.

The bad thing about air pockets... it could mean something serious is wrong. If you flush everything and bleed the system of air and are still getting air into the system, it could be headgasket related.

And if you drive it while it's red, that is very bad for the engine. Stuff is going to warp.

 

I had a car constantly doing what the OP mentioned about the temp guage. It would constantly develop air pockets.
Finally found the cause was failed head gaskets (compression gases getting into the cooling system, really NOT good). Changed the gaskets and I still drive that car as a daily.

There are other diagnostics to do before jumping to head gaskets. Like Chibi said, bleed the air out of the system, make sure that is all good first.

 

also if you can, get someone to do a cooling system pressure test. what that does is basically pressurize the cooling system and then you can see if you can find any leaks anywhere