The blower motor stays running and will not shut off?

Hello,

It sounds like you have a blower motor relay that is stuck if the system is manual and a blower motor speed control for the automatic system. Here are the locations for each and the blower motor wiring diagrams for both systems. Check out the diagrams (Below)

Good to hear, please use 2CarPros anytime we are here to help.

Cheers

To clarify, are you talking about the engine cooling fan (under the hood), or the blower fan (for heat and A/C)?

If you are talking about the cooling fan, then we are likely looking at a relay gone bad. That relay should be in the under hood fuse/relay box (under hood, left side, behind battery). Starting with the high speed relay, pull it out and see if the fan turns off. Replace the one that causes the fan to go off when removed. I have attached images to help you.

And here is a link to general information about relays: https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If, however, you are talking about the blower/HVAC fan, then it could be a little more complicated. I will walk through that with you if necessary.

Keep us posted.

I attached a diagram for you to view. It shows the circuit for the blower motor. Can you check for power to the blower motor with the key on and the fan in high speed selection?

There is a blower resistor that is common for failing. It is next to the blower motor.

Roy

Try this, Some customers may comment that the blower motor is inoperative or continues to run after the vehicle has been shut off.

Cause
These conditions may be caused by a blower motor control module failure. This failure may occur when the vehicle is operated in ambient temperature conditions of -23 °C (-10 °F) or below.

Correction
Important: Replace the blower motor control module if the vehicle experienced a blower motor control module failure in extremely cold ambient temperature conditions.

Technicians are to replace the blower motor control module, also called the Linear Power Module (LPM), with the P/N listed below. Refer to either the Blower Motor Control Processor Replacement or Blower Motor Processor Replacement-Auxiliary procedures in SI. After replacement of the blower motor control module, the customer may notice a slightly higher than expected blower motor speed at any of the blower speed settings.

Parts Information
Part Number
Description
Qty

89018849
Module Assembly, Auxiliary Blower Motor Control (Rear System on Escalade ESV, Suburban, Yukon XL)
1

89018964
Module, HTR & BLO & A/C CONT (Front system only vehicles - Except H2)
1

89023355
Module Assembly, Blower Motor Control (H2 Models)
1

89024926
Module Assembly, Auxiliary Heater & A/C Control (Rear System on Escalade, Yukon, Tahoe)

Some customers may comment that the blower motor is inoperative or continues to run after the vehicle has been shut off.

Cause

These conditions may be caused by a blower motor control module failure. This failure may occur when the vehicle is operated in ambient temperature conditions of-23 °C (-10 °F) or below.

Correction

Replace the blower motor control module if the vehicle experienced a blower motor control module failure in extremely cold ambient temperature conditions.

Technicians are to replace the blower motor control module also called the Linear Power Module (LPM) with the P/N listed below. Refer to either the Blower Motor Control Processor Replacement or Blower Motor Processor Replacement-Auxiliary procedures in SI. After replacement of the blower motor control module the customer may notice a slightly higher than expected blower motor speed at any of the blower speed settings.
This is a common problem, this should fix it.

Almost all high current devices are powered by a relay. There should be a relay control in the fuse box or the power distribution box under the hood. If you have the owners manual try locating it and removing the relay from the socket. It sounds like a sticking relay. If you have more questions please post back or PM me. I'll do what I can to help.

Dave

This vehicle operates a little different then some others as it has a high blower speed relay. I suspect the relay is stuck on causing the resistor to be bypassed and the blower stays on high.

Here is a guide that will help with testing this relay.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I am attaching the info below on this and what I would suggest is replacing the relay and retesting the system as I suspect this will fix the issue.

Please let us know what you find. Thanks

No, we would test the wiring to see if it is being told to stay on but it may be easier for you to just try a new relay.

I am attaching the wiring diagram and info below. More than likely you have a control processor issue, which is basically the resistor.

The HVAC control module is to send the speed control signal to the processor which then changes the fan speed. When this shorts it usually puts the fan to high speed.

Please check the voltage to the processor and I am sure you will see that it is the correct voltage which means it is shorted.

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

Please let us know what you find with this. Thanks

Hello, I'm Danny.

Here is the information you requested. It sounds like you are having a problem with the blower motor resistor. It was a common problem from the early to mid 200's truck being defective. You might want to check the blower motor wiring harness to be sure it's not melted or burnt which was the common problem causing your blower motor symptom. Here is a electrical wiring test tutorial in case you need to check or repair any wiring on the blower motor wiring harness:

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

I've attached picture steps below on how to replace the blower motor resistor and its location on the hvac box under dash on your truck. The problem was so common they made a replacement wiring connecter by Dorman available at all local auto parts stores as an alternative replacement as a lower cost than a Chevrolet dealership. Hope this helps and thanks for using 2CarPros.