Questions and Answers

Mazda Truck Has No Heat

Q. Hi, I have a 1997 Mazda B2300 Extended Cab Truck with 77,000 miles on it. It is basically equipped with 5 speed manual trans, A/C, power steering, & power brakes.

For the most part the truck has been fine. At 72,000 it had to have the radiator and thermostat replaced.

Recently, the heater seems to work only when it wants to. Now that summer is officially over and so will the fall, that is not such a good thing.

If I leave the thermostat knob (middle) over in the "heated" area and place the selector knob in the vent or bi level mode when I park the truck at night then maybe the heater will work in the mornings once the engine warms up.

I pulled the front dash panel to take a look at connections etc and they all seem to be fine. I hear the customary "whoosh" of vacuum when I move the selector knob from "Off" to any of the other positions. Any help you can provide would be appreciated.

Thanks,
Tony G

A. Well Tony, assuming the radiator and thermostat are fine since they were just replaced, we have to look inside the dash.

The problem is most likely in the door that diverts air either through or around the heater core. What you will need to do is get under the dash on the passenger side and check to see if the door moves when you change the temp setting. If it doesn't, then the vacuum motor may be bad. Disconnect the motor and try to move the door by hand, if it moves freely, then replace the motor. If it doesn't, then the heater box has to come out and the door repaired.