Blown fuse, bad fan speed control switch, bad blower motor resistor pack, bad blower motor, or loose or disconnected wiring.
A possible cause could be that you have a clogged heater core.
A loose wire would cause the horn to stop working on your Dodge Avenger 2.4L engine.
Leaking heater core
A blocked heater hose could cause a leak. A stopped up heater core could as well. Or the connector in the Windstar could be cracked.
could be fans not working, thermostat, blown head gasket, broken or leaking coolant lines, bad heater core
Could be because the coolant level is too low. With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!
Blower motor not working: could be the electric motor, or A fuse, or A short. Blower motor working: could be low engine coolant, or A stoped up heater core, or loss of vacumme to the inside of the car from the engine, or A bad water pump, or A bad thermostat.
If you are absolutely, positively sure that your coolant level is not low......then your heater core could be plugged. Or the control that turns the coolant flow on/off to the heater isn't working. Make sure the control is working, the flush the radiator. Should cure the problem.
Yes it could also cause the A/C to stop working.
If you have lost a sufficient amount of coolant this will stop the heater working because there will be no hot water in the heater rad.
There could be multiple reasons why a heater would stop working in a truck. There could be low coolant or a bad fuse to make a heater stop working in a truck. The best way to find out the reason is to take it to a certified auto mechanic.
If the air conditioner in a Mitsubishi Legnum is not working, there could be a blown fuse. There could also be a loose cable, or a problem with the heater motor.