If anyone can help, some info would be appreciated. My girlfriend drives a 94 corolla that her dad gave her, and recently when she drives the heat goes on and off. My initial idea is that her thermostat is bad--I came up with this since on her dash the engine temp gauge fluccuates from cold to warm. Anyways, my first question is does everyone agree with me or could it be something else? Also, I havent even looked under the hood yet, but I figured since she worked 40 hours during the week that I could do it on the weekend for her when I see her. So, if anyone has a similar year corolla, could you describe where the hell the thermostat is or have pics of where it is. I cant find anything on the internet other than pretty vague descriptions. Thanks.

 

It sounds like a thermostat problem. I just replaced one on a Civic, and it cost $20 and took about 45 minutes to replace it (first time I ever did it).

The only other possiblility I can think of is an airlock. Sometimes air in the system can cause these symptoms, so if replacing the thermostat doesn't fix it, try taking it to a shop and have the coolant flushed and refilled.

I don't know exactly where your thermostat is, but if you follow the hoses from the radiator to the top of the engine block, there will be a small housing between one of the hoses and the engine block, and that's where you'll find the thermostat.
It should be as simple as removing a hose clamp, opening the housing, and replacing the thermostat. Just make sure you put the new one in exactly the same way as the old one - mine has a valve to allow air thru the thermostat, and it must be positioned in the 12 o'clock position.

 

Might be a good idea to wait until the engine is cold?

 

Probably the thermostat, very cheap and easy, just be sure to refill the coolant!

 

thermostat