I have a 97 Acura TL 2.5 and the heat will not stay steady. I turned the heat all the way up and sometimes it works and sometimes it just blows out cold air. I am not sure what to do besides going to the dealer and let them rape me on the diagnostics check which is $90. Any suggestion? I am thinking that my Thermostat is out or going out.

 

What are other symptoms of your car? Before anything else, check the coolant levels in your car, and make sure they are topped off. Does the temp guage stay consistant while driving? If it heats up when idling, but cools down rapidly when driving then it is the thermostat(replaced mine yesterday)