1986 pickup air won't blow
#2
Nothing turns on?
Nothing makes a sound?
A problem well-stated is a problem half-solved

Here's the schematic.

Suggest you check the fuses and check for voltage at fuse and relay as shown in schematic. Fuse and relay are here:
Last edited by RAD4Runner; Jun 13, 2013 at 09:11 AM.
#6
Last edited by RAD4Runner; Aug 4, 2013 at 08:52 PM.
#7
If you look at the schematic that RAD4RUNNER attached, you will see that all of the switch positions have a common pivot point which is tied to ground.
When you turn the heater switch to LO, it provides a path to ground for the relay coil, which closes the relay contact. Current flows from the contact through the fuse to the motor, but the only path to ground for the motor is completely through the resistor. With all of the resistor in the circuit you have the lowest speed.
In M1 position the relay works the same as above and the path to ground for the motor is through M1 to ground which is 2/3 of the resistor, which is a higher speed than LO.
In M2 position again the relay works the same and the path to ground for the motor is through M2 position which is 1/3 of the resistor, which is a higher speed than M1.
On HI, relay works the same, the path to ground for the motor is through HI, which bypasses the resistor and of course with no resistor in the circuit you get the highest speed of all.
So, if the resistor was shot (open) and the rest of the circuit is ok you will get high speed only.
When you turn the heater switch to LO, it provides a path to ground for the relay coil, which closes the relay contact. Current flows from the contact through the fuse to the motor, but the only path to ground for the motor is completely through the resistor. With all of the resistor in the circuit you have the lowest speed.
In M1 position the relay works the same as above and the path to ground for the motor is through M1 to ground which is 2/3 of the resistor, which is a higher speed than LO.
In M2 position again the relay works the same and the path to ground for the motor is through M2 position which is 1/3 of the resistor, which is a higher speed than M1.
On HI, relay works the same, the path to ground for the motor is through HI, which bypasses the resistor and of course with no resistor in the circuit you get the highest speed of all.
So, if the resistor was shot (open) and the rest of the circuit is ok you will get high speed only.
Last edited by Hadmatt54; Aug 5, 2013 at 04:36 AM.
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