This morning I had frost on the windshield, started the Aztec and waited for the defroster to do its job, after 5 minutes I went back out to check and it was blowing cold air at the windshield. 2 weeks ago I had to flush the radiator because the vehicle started to overheat....this morning I did notice the temperature gauge fluctuating strangely. Maybe related to this issue?

Update from Oct 8, 2012: I watched a video on you tube, it helped, if you have this problem you need to flush your radiator. Put dex-cool fluid back in, even though lots of folks say this stuff is bad, GM says you have to use it. After you have flushed you radiator and replaced the drain plug, fill the fluid back up, leave the funnel in the fluid hole, then fill your overflow to the arrow on the side....get in the vehicle, turn your heat all the way to the hottest setting, leaving the fan off, start your motor and rev it to 2500 rpm's until it heats up. leave the motor running, get out and fill it radiator the rest of the way up, this lets your heater core fill up. This fixed my problem.

Ok, we had to take Aztec out of shop for A/C problems (in and out since Nov 2010) in order to put our other car in another shop. On our way to pick up the other car, the Aztec's heater stopped working and car started running hot. So, we traded the cars at the shop. I'm laughing but really want to cry. We haven't heard the diagnosis yet. BTW: The other car ended up with a second problem and also the mechanic ran into it with another car and had to send it to the body shop. Still laughing. FYI: If I can be a stay home mom at age 47 to a 2 year old BOY, I can get through anything!!!