My mother has had this car for 3 days. Tonight I tried turning on the heat, and it was still blowin AC.
It's a 2000 GXE with climate control. If I set it to auto and turn the temp up all the way, I can still hear the AC compressor kick in, and it blows ice cold AC instead of heat.
Has anyone had this problem before? What could it be?

 

The A/C will still on the, as it's used to keep the air above the dew point. Try turning the heat up 3/4 of the way and let us know what happens.

 

I have heard of this problem before. Check out the thread below. Hope this helps!

http://forums.maxima.org/showthread....e+control+cold

 

I tracked down the problem today, it turned out to be air in the cooling system, the hoses going to the heater core were both cold.
I bled the air out and now the heat works, I also ran the diagnostic test for the climate control before I fixed the problem, there were no codes, but there are parts of the test where it's supossed to be blowing full hot with the compressor on, and it was still blowing cold AC. If I set it to auto and set the temp to max, it still blows AC, I have to turn off the compressor by selecting manual mode for everything in order to get heat.

 

It's probably just your heater core altogether.

 

Are they a common problem on these cars?

 

Not at all actually. So this is pretty weird. Unfortunately, I know that the heater core is a fairly expensive item.