I have a 1994 camaro z28 lt1 and the heat won't work. The only time it works is when i got stuck in the snow and burnt half a tank trying to get it out and the temp gauge got to half but when i drive it normally it will only get to a quarter of the way up. I replaced the thermostat, new radiator cap, water pump is not leaking, could having too much anti-freeze in it make it have no heat? The head gaskets from what i see are not leaking by the way.

 

could be a clogged heater core. what thermostat did you put in it? Was it a 160*? or 180*? if you replaced it with a 160, that would be the cause

 

http://shbox.com/1/4th_gen_tech2.html#heaterflush

 

It is kind of hard not knowing what thermostat you installed. If it is a 160*thermostat, while driving, it will not go much past a quarter, but you still should have heat. Let your car run at idle for awhile. See how hot it gets. Being in WI, we have had days with -5* high temperatures, so it will take longer to heat up. So if it is the case of NO heat coming out of the vents, I agree with Shoebox. If it is a case of the car not heating as hot as you would like it with a 160* thermostat, I would consider that normal operation.