Replace your heater selector switch
The ac unit compressor will run when it is in defroster mode and heat setting is on.
Check that the wire on the rear defroster is connected to the defroster. If broken off repair it.
you have to make sure there is no short and check for voltage amount at the strips of the window to make sure defroster is working
you either have a blowed fuse or a wire crossed
most likely your air conditioner needs recharged per my mechanic brother-in-law
It should if the system is in good working order.
Bad fuse
change the bulb
bad temp sender usually. Bad gauge rarely.
My 96 corsica does the same thing, so maybe this will help: I have a small coolant leak, and I have to put more antifreeze in quite regularly. when my coolant level is too low, my heat stops working. try checking your coolant levels, remember to use universal or dexcool.
There is a repair kit available to repair the grid. A test light will find the break in the grid.
Heater is not working in a 2002 ford foucs only work when fan setting is place in?