ok, my brother has a 97 fullsize that had no heat. we replaced the thermostat and now the truck warms up but still not much heat inside the truck. also, the fan switch only comes on high no matter what position the fan control switch is in. someone please help. have no idea how to fix this.

 

ttt.................

 

No heat would probably mean coolant is not flowing through the heater core. I can think of two reasons (there may be more): Heater core is clogged or clogged somewhere on the way to it, or the HVAC control unit is not operating properly, thus not allowing any coolant to flow through the heater core.

I don't know about the fan problem, but could be HVAC control unit related as well.

 

anyone else......

 

Are both the lines , in/out, of the heater core hot?? If not its clogged up. If they both are hot then either the control panel is switching from cold/hot or the temp actuator isnt working . Do all the modes work? As far as the fan speed, Pull the plug off the fan resistor and check for power in each position of the fan switch. If you have power in a different spot when you swith fan speeds then your lookin at replacing the fan motor resistor.

 

cool thnanks you guys, i'll check this stuff out. do yall know how to change the resistor?

 

Its not that hard , just might have a time with the bolts because of their location. Find the resistor, unplug it, and then take the 2 or 3 bolts out.