Blower fan not working at any speed

I can understand your issue because this blower motor is a two wire motor meaning you put voltage to one side and the other side is "ground."

However, in this case the blower relay feeds power to the blower motor and then the ground in this case goes through the resistor and back to the control module. This is called a ground side control device which means the HVAC module will increase resistance in the FET/resistor to slow the blower motor. When there is an increase in resistance behind the load in a circuit it takes voltage away from the motor to make it through the added resistance later in the circuit which slows the motor down.

So when you took the ground to actual ground, you bypassed the module and it is no longer a completed circuit.

Let's start by putting the wiring back how it was and then check voltage at both pin 4 and 5 at the HVAC module with the blower motor on high.

Let me know and we can go from there. Thanks

Okay. So with the relay in and the blower motor on high you have 0 volts at the HVAC Module?

If this the case have we checked the blower motor to see if it even comes on when we give it power and ground separate from the vehicle? Basically just take two jumper wires and connect the to the battery positive and negative then apply the 12 volts to terminal 1 of the actual motor and the ground to pin 2. The motor should come on. Once we confirm the motor works we can revisit this. Thanks

Okay. This is an odd one so let's circle back and take voltage readings on both sides of the motor on each fan speed, because it feels like we are missing something or making an assumption that is not accurate. That is normally the case when we have something like this that doesn't seem to make sense.

So one lead on the input side of the fan and the black lead of your meter on a ground stud or some other ground. Then on the other side of the motor with your red lead and the same ground with your black lead. Do this for each speed and let me know the voltages.

Thanks

So these were at the points in this diagram with the fan plugged in and on each setting? The fan didn't run at all when you took these as well?

I am asking this because those look backwards at best but just not correct for each setting. I expected the input side to be around 12v and output around 0 on high. Then changing as you dropped to low. On low setting I expected the input to be around 4 volts and then around 8 volts on the output side of the fan. Basically the more voltage the fan uses the faster it goes. High should be the speed it was when you put 12 volts to it to check the operation of the fan.

At this point, the only thing I can think is the HVAC module is screwed up but you said you replaced the control panel. That was the picture below correct?

If that is the case, the only thing left is wiring. Are familiar with taking resistance reading on the wiring? Basically you unhook the connectors on both ends and then take ohm readings on that wire. It should be less then a half ohm on each wire.

Let me know and maybe the best this would be is to run a couple new wires as an easy way to find out if it is wiring. Thanks

Okay. Before you do that, was this issue the same before you replaced that and did it make any change? Before you buy another one, put the old one back in and take the same voltage measurements. It is highly unlikely that they are both doing the same thing.

Sorry for the delay. Yes. I would go with that. It just doesn't seem like a control module but with the wiring not having high resistance or opens and everything else works. I am not sure why I thought you replaced that already. I re-read the whole post and I must have just assumed it. I would do it and we can go from there. Thanks

Okay. Clearly this is not making much sense but I think we have a grounding issue with the FET. You can run a redundant ground from the FET to a good ground. Then we need to check a couple other things. First the ACON fuse just to make sure. Lastly measure voltage at the power wire (number 5) at the relay and tell me what you have.

We will figure this out. I am sure of it. Thanks