Heat works when truck s moving, thats it...

[Giantsonearth.com]

I have a '97 Ranger XLT. I had my heater core fixed about 2 years ago. My fan control only worked on high. Then it stopped working all together. Now I only have heat when I'm moving. Can anyone help?

 

[triumphrider-1]

Sounds like you need a new resistor.

 

[odie1969]

Maybe cause the vent door that allows air in from the outside is open, so as you drive air is coming in the cowl and through the heater core causing the cab to warm up. where as before you had the fan sucking in air from the outside and pushing it it to the cab.
I would start checking the resisters going to the fan circuit and the maybe the switch it just may have gone bad. good luck

 

[martin]

Sounds like you have more than one problem. First check that the blower motor is working by putting 12v directly to it. The motor should run at full speed even if the ballast resister is bad but if the connections to it are bad it might stop it completely. my guess is that the motor is bad, also the ballast resistor and it's connector.