Topic: 84 - 89 toyota pickup

[BGrednckyoter]

i am having a problem with my heater when i bought it the heater only worked on high and it still does i was told it was the heater control switch/module. i was told it was up under the dash by the control switches. if you could help me out with it would be great

[Homefries]

The only working on high speed is a typical sign of the blower motor resistor burning out.  It's located on the firewall on the passenger side.

[BGrednckyoter [OP]]

ok thanks i will take a look at it and see if that is it

[BGrednckyoter [OP]]

ok i just look  and i don't have one but i don't understand how it can work one high. it must just be wired together to work on high

[Homefries]

It should have one unless the PO bypassed it.  If you pull it it should have 3 wire coils, 1 for each speed with a different resistance setting. 

Try looking for the blower motor.  Follow the wire bundle from the motor to the firewall, about 3" away (directly towards the front of the truck from the blower motor) approx. 10" above the floor it should be screwed into the firewall. Yank it out and see if the wire coils are burned out.