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
Your car's defroster may not be working due to a few common issues. It could be a problem with the blower motor, which may have failed or become blocked. Additionally, a malfunctioning thermostat or low coolant levels can prevent the heater core from warming up the air. Lastly, check for any blown fuses or damaged wiring in the defroster system.
you either have a blowed fuse or a wire crossed
most likely your air conditioner needs recharged per my mechanic brother-in-law
A defroster not working in a Ford Focus can be caused by several issues, including a malfunctioning blower motor, a clogged cabin air filter, or a faulty thermostat. Additionally, low coolant levels or a failing heater core can prevent warm air from reaching the defroster vents. Checking these components can help identify the problem. If the issue persists, consulting a professional mechanic may be necessary for further diagnosis and repair.
To fix the back defroster in a VW Cabrio, first check the fuse related to the defroster circuit, as a blown fuse can prevent it from functioning. If the fuse is intact, inspect the wiring and connections at the rear window for damage or corrosion. Additionally, ensure the defroster switch is working properly. If these steps don't resolve the issue, the rear window heating element may be faulty and might require replacement.
It should if the system is in good working order.
Bad fuse
change the bulb
bad temp sender usually. Bad gauge rarely.