Heater controls go 1 through 5 but 5 is not working

Hi,

Just for future reference, when the resistor goes bad, usually the highest speed is the only one that works. In this case, it was the opposite. Check out the diagrams (Below).

This is how it works. When you select any speed other than high, power is sent through the resistor. Based on the selection, the resistor causes less voltage to reach the blower motor. Thus, the speed is controlled. When you select high, power runs direct (12v) so the motor runs the fastest.

In this case, there can only be a few things wrong. First, the switch is bad and not connecting on the high setting. Second, the blower motor relay is bad and not letting power reach the motor. Or three, we have an open circuit. If it was a fuse or a ground issue, none of the speeds would work.

If you look below, I attached the wiring schematic for the blower motor specific to this vehicle. The first thing we need to check is if power is present at the orange wire right from the switch when high speed is selected. If there is no power, the switch is bad. If there is power, then we need to jump to the blower motor resistor/relay and confirm power is present at the orange wire in at the relay. If it is, you got a bad part. If it isn't, we have an open circuit. You will need to follow the orange wire back to the switch to check for a break in it.

I had to cut the schematic in half to make it readable. I did overlap them so you could follow. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

If it is only High that is not working then we need to check the voltage getting to the relay. The way this works is the High setting passes from the coil side of the relay and goes directly to the motor so that it gets the full 12 volts.

When you set it lower it runs it through a resistor or multiple ones to slow the motor from lower voltage.

So you should have 12 volts on the orange wire from the control module. If not, then you have a control module or wiring issue on this orange wire.

https://www.2carpros.com/articles/how-to-check-wiring

Please let us know what questions you have. Thanks