Heater not working help



Hey guys so I’m trying to fix my heater and a 1986 Isuzu Trooper I have a second one I’m using for parts I tested my blower it is functional I checked the fuse and there was no power at the fuse so I thought that maybe it could be the AC temperature control switch I replace that with the other one from my other car it is a temperature control unit without AC it is still not working do you have any ideas


Probably just me, but I am confused. What did you test, your “second” heater? No power to the fuse. Did you check the fuse? Can you give more details in the order you tried to troubleshoot? What does the heater do, if anything?


So the fuse that is a 10 amp fuse located in the fuse box is for the rear heater my truck is not equipped with the rear heater there is no fuse in the fuse box that goes to the heater I looked at the schematic there is supposed to be an inline fuse somewhere but I cannot find it underneath the dash I am in the process of taking the instrument panel off to locate it there is only one relay located on the schematic it is on the heater box itself I have replaced that with another relay still not working and then I replace the AC climate control with another one still not working I have replace the blower motor still not working


some punctuation in that post would make it readable. As it is, it’s not.


What you’ve got to do is trace the circuit to see where the voltage is getting interrupted.

Battery + … AC Temp Switch … 10 amp Fuse … in-line fuse …resistor … + blower motor - … ground.

Start at one end and work towards the other. You know for certain presumably you have 12 volts at the battery, and you got 0 volts at the + lead for the blower motor. It’s just a matter of where in between the circuit isn’t passing the voltage through like it should. There’s usually a blower motor resistor like I put in the diagram above, and those are common failure items. But they usually only fail at the lowest fan speed, not all fan speeds.


I have replace the resistor, I have replaced the resistor relay, I have replaced the heater AC relay, I have replaced the blower motor, I have replace the heater core but I cannot find anywhere an inline fuse


Probably under the dash on the passenger side