No heat 1991 Ford Explorer

Answer 1

"No heat" is pretty generic. If you have no fan then the problem is electrical. If you have no heat then the problem is in the engine cooling system. If you have heat but can't move it (it only comes out the vents or defroster, etc) then the problem is in the ducting under the dashboard.

We'll talk about heat. The temperature slider inside the truck is connected by a stiff wire to a valve under the hood. The valve opens and closes to let hot water from the motor into the heater core (a small version of the radiator) inside the truck. The fan blows air through the heater core and in to the air vents under the dash. If you get hot air anywhere, the heater core and hoses are working.

If you have no heat it could be as simple as the coolant (water/anti-freeze) level is too low to fill the heater core, or the hoses to the heater core (one goes in and one goes out) could be blocked.

Some other options are bad valve, bad control head or wire, bad thermostat (you would see that your engine temp isn't right), or the heater core is disconnected.