The heat works when it feels like it. The fan works the A/C works and the heat comes and goes as it feel like it. We have replaced the themistat was working great 5 hours later not working at all.

Need a bit more here but I can get you going. Is the fan not coming on and you can feel heat or is there not heat at all. If you can feel heat and the fan is not blowing then it is your blower motor or your control panel. First thing to do if you do feel heat is to pull the fan out, hook it up to a 12 volt source and test it. If it runs then it is your switch.

sounds like a baad capacitor or fan motor.

Replace the fan motor.

It wont if any thing it will make it worse if u put to mush in check out ur theorem stat also check out fan switch on rad if not working replace it to check pull wires of and join to geather shud work if ok

The indoor fan will continue to run. When heat pump goes into defrost the outdoor fan stops, the reversing valve switches and the unit is basically working in the cooling mode. In order for you not to feel a blast of cold air in the winter the electric strip heat also comes on so the indoor fan must run while the strip heaters are on.

This sounds like a BSC blower speed controller. To diagnose turn the key on engine off, its located under the heater hoses on the a/c case. Wiggle the connector and the fan should start to work, then replace it.

Check the thermostat, the radiator hoses. The upper radiator hose should feel warm/hot. The lower radiator should feel cold. Check the radiator to be sure it is not clogged/rusted. Last Resort: you may need a new heater-ccore.

do you keep the fresh air button on ? if you do , you will feel heat or cool air come in with out the blower motor running

The fan for the A/C should blow harder than in heat. The fan should be on high for cool and low for heat. You can change the heat setting for medium but I would not recommend it because it may make heat coming out feel less.

You may want to take the cover from the fan cage and make sure you dont have a mouse nest in there, or the fan blade is slipping on the shaft. Good luck, RC