Blower fan not working at any speed

Good morning,

Can I approach this in a different way?

Can you tell me if you have voltage to the red/white wire at the blower with the key in the on position?

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

I attached a diagram as well.

Roy

Okay, good.

What about the white wire?

When you remove the plug, does the white wire have power?

Roy

At this point, it is looking like the FET is the issue.

Roy

So anytime we get to a point like this, we are either missing something or making an assumption of something that is not true. So I understand that you have taken all these measurements but can we write them down on one sheet of paper and that may jump out at us as to what the issue is.

Then list the parts that you have replaced that I am missing in this list or if you didn't replace one of them.

1. FET
2. Blower Motor
3. Blower Relay
4. Control Module

In the last 12 years as a service engineer, I have had some tough issues but always figured them out. This one is confusing because we are assuming something is supposed to work a way that it is not.

It will require patients but I am sure we can figure this out. Thanks.

So we may be circling here but you have 0 volts at number 3? If so go back and check it at the fuse and see if you have 0 volts. You should have 12 volts on this wire at all times.

Okay. Let's check voltage drop on that wire from the junction block to the relay. Basically just measure voltage from point 1 to 2 with the relay in and the blower turned on.

Then measure voltage from point 2 to 3 with the same settings.

Lastly to prove out the entire control side of the system let's just 12 volts to number 3 and then try to change the fan speed using the normal controls. Are you able to increase and decrease the fan speed when you put 12 volts to the fan?

I don't know. That is not on any of the wiring diagrams. It only shows some inline connectors not a module. Is there a part number on it?

I just want to confirm you understood what I was asking for. I know you have those voltages at those spots on the white wire but I want you to do a voltage drop test on the white wire with everything hooked up. That means put your black lead at one end of the circuit and the red at the other. Take a look at this diagram. This will tell us what the voltage is on that wire.

So I found that as well and that is the inline connector. I am not sure why it looks like a module but it appears that is all it is, is just a connector. It was hard to tell from your picture but does it have wires coming out of both sides? If it does then that is an inline connector.

If so, I want you to unhook the other inline connector and run a wire from the fuse to the relay. You should not have 5.5 volts on that circuit. That is just a wire from the fuse to the relay so I would expect there to only be less then a volt. That indicates there is resistance in that circuit. If you run a wire from the fuse to the relay see if the fan turns on. If so you need to run a new wire and you can just bypass those two inline connectors. We can talk more about that after we find out. Thanks

Okay. I understand. Please let us know if you ever find out what it was. Thanks for the update.