2017 blower fan not working on any speed

Looking for some guidance. I have searched this thread and all of google I feel like. Tons of info for 2nd gen and older blower motor issues and the resistor is typically the issue.

The issue: Parked the truck overnight, prior to this no issues at all with blower motor fan / ac working just fine. Start the truck up the next morning and the blower motor will not turn on at all. Regardless of the fan speed setting. Everything else on the HVAC seems to work just fine.

Checked every fuse under the steering wheel, and in the engine compartment and did not find any blown. The only one that doesn’t light up with a test light is the A/C 10amp in the engine compartment. However my understanding is you can’t turn on A/C without turning on the fan.

The blower motor has been replaced. The resistor has no signs of being burnt out. The connectors have been checked and all appear in good shape and no signs of over heating. The wires have been wiggled to test loose connections with no luck. The dash has been taken apart and the fan speed knob connections all look good, unplugged and tested again. Still no fix.

I feel like I’m missing something simple.

If this has been asked already I apologize as I’ve searched and searched.

 

I’m thinking the [New] motor went bad- can you test it directly with separate 12v leads? And did your tests include using a multimeter to see if the motor was getting power?

 

New motor (purchased from the stealership) was installed and the issue persists. Have not tried the multimeter just a test light so far.

 

You should still test the “new” motor, there’s no rule that says a new part can’t be bad. Assumptions are what makes diagnosing a problem much worse.

 

I’d co-sign this. Try testing the harness that plugs into the blower motor.

 

Check if the blower works when set to heat. If so, it's probably that 10A A/C fuse you chose to ignore.

 

Thank you for the good suggestions so far. Just checked and the new and old blower motor does activate when plugged direct to power. Sourced a multimeter and the plug going into the blower motor does not seem to be getting any power when the ignition is on.

 

Valid point. Tested both old and new to direct power and they work. Thank you for the suggestion. Seems like the power isn't making it the blower motor plug based on the multi meter test.

 

Tested the fan settings on all speeds and all variations of temperature. No luck. Fair assumption that I ignored the 10A fuse. It was pulled, checked and tested on a known working terminal. All showing that the fuse works.

 

Do you have the [Auto] button?

 

Good start checking the new motor.

Edit: this was assuming the fuse is blown>>> I’d put the multimeter in amp mode (set it to amps higher than 20amps) and connect one of the leads on it to the motor. Run power through the other meter lead so you can see how many amps the motor is using when it’s running.<<<

Also check for power running to and through the switch… you can disconnect it from power and use the meter in continuity mode to see if it’s working correctly in different settings- but check to see if the switch is getting power on the downstream side first.

The other thing that may have happened is you have a break in the wires somewhere- maybe from a rat chewing a harness somewhere? Hope it’s not that!

 

This is manual or non auto.

 

I know this is overkill. But…. Always test power at the device in question.
This is good practice for any powered devices.
Good luck. I’d also check the plug

 

Thank you for the suggestions. Going to give that a go.

According to the fuse box cover it should be 10amp and that is what was in there. (attempted to attach picture)

 

Attached is the schematic for your setup. Blower motor is located on page 2.

 

Thank you for this!

 

I'd say it's the resistor...

 

So check for power on both terminals of the motor with an unrelated ground like a bolt, dash brace, etc. if you have power then it's a ground issue, if not then the heater relay side of the circuit is your issue... could be the relay, the wiring or 50A "htr" fusible. The 10A a/c fuse having no power seems like a tell tale to me of the 50A being blown. If it is then you need to investigate for a short somewhere. Ideally you can do a continuity check between both terminals of the blower motor(reason for this is mainly to check for the power wire being shorted to ground, checking through the connector is for connivence vs. An external ground) and if you have continuity then you have a short to ground somewhere... to find it you'll have to wiggle wires and follow them looking for the issue. If you have no continuity between the terminals of the connector then I would install the NEW motor and send it. The old motor could be drawing high current and blew the fuse. It could possibly be the resistor too but the diagram shows a circuit protection device inside it so I would try a motor first.

Also
An incandescent test light it good to use for circuits that draw current at full voltage like motors but not for testing computer outputs because an incandescent bulb will actually load the wires so you know if it can carry a current and not just a single strand passing voltage which is essentially what a multimeter alone will show

 

[QUOTE="joba27n, post: 29051025, member: 366948"The 10A a/c fuse having no power seems like a tell tale to me of the 50A being blown. [/QUOTE]

 

[/QUOTE]
Provided I read your post right of the 10A not being blown but having no power to either side of it. Could also be an issue with the control side of the relay circuit/ the relay