i have a 1991 Ranger xtra cab with a 4.0- cam, headers etc. and i cant get my heater to work. The core is new, i replaced the thermostat and the fan works fine. Any suggestions?

 

sounds stupid but is the control panel broke at all on the dash? happened to my moms merc once, the rod that controled the heat broke so it never moved... only idear i got right now

 

Assuming the heater core hose is hooked up it just about has to be either the controler, a vacumme line, rod, the blend door actuator, or the door is stuck.

I'd first look for a rod that's off or a vacumme leak. (I'm not familiar with rangers HVAC systems)

Rich

 

Is the truck running at a normal temp?? Is the gauge reading hot or cold??

 

i put a new thermostat in monday....195 degrees
but the temp guage will sometimes fluctuate up to 230
and drop back down to 195. did i get a bad thermostat?

 

More than likely your seeing air in the system.

Once the motor is fully warmed up turn the heater on full hot & do several 0-50mph WOT blasts. Do it again later as well.

The point being that the t-stat is closed 1/2 the time and just a single blast may not catch the stat open.

You could also do this in your driveway.. Drive the truck til it's fully warmed up. Then park it and set the parking brake.
Now put your hand on the top rad hose. You'll feel it get hotter / cooler over a few minutes time. When it *clearly* gets hotter the stat is opening. At this point free rev the motor suddenly. (with the heater on)

It's very UNLIKELY you have a bad stat. When a new one fails it does'nt open.

Rich