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)

Yep you where right it was the speed controller I have an automatic system. Thank you so much!

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

Cheers

All of sudden the fan motor started running on high speed and will not cut off of high no other way than the ground off the battery, could not find on fuse panel the fan fuse.

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.

To clarify it is the AC/heater fan.

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

My blower motor stays running on high, controls have no effect, runs even with key removed. Only way I can shut it off is to remove the relay, I've already tried other relays, no difference. I'm not sure if this is relative, but I just had it oiled before this problem started. Any advice would be greatly appreciated, thanks.

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)

my blower motor is staying on even after i have cut the truck off and opened the door.

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.

My blower/heater motor switch will not turn off the blower nor willl it change the motor speed. It's currently stick on high. even if I turn the engine off and take out the keys the blower is still running. I had to discoinnect the battery to get it to stop. If you can direct me to the part I need to check and or replace I would greatly appreicate. a contribution is on it's way because I need to fix this right away.

Thank YOU!!

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

I have replaced the blower motor, the resistor, and the fan speed switch. The blower motor constantly blows on high and will not shut off even after the ignition is off. I have asked countless mechanics and they are all baffled. Any ideas? I dont want to send my truck to a mechanic that won't be able to fix it or have an idea on how to fix it. I have checked all the fuses and relays. Please help.

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

I will try that. Thank you.

Would replacing it be the best option or is it something with the wiring.

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.

a/c blower motor runs on high only and keeps running after turning ignition switch off

This is most likely due to the relay (resistor assembly in this case), as it is most likely failed and stuck on high.

Here is a guide that will help in testing the relay:

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

If it were me, I would just go ahead and replace this as this is sure to be the issue.

I included the process to replace it as well as the wiring diagrams below.

Please let us know if you have questions. Thanks

Hello my name is Dave.

The first suspect is a stuck high speed blower relay, I am attaching the diagram that shows the wiring for it. There is also a small chance that there is a short to positive between C2, C1 and B2, however I would be surprised if that was the case. If you can find the relay and unplug it and see if the blower stops then that would eliminate a short between C1and positive, if it still runs with the relay unplugged there has to be a short between C1 and positive, in that case look for melted wires. Again I strongly suspect that the relay is stuck in the high on position.

To further help you track down the problem here is a link to our tutorial on using a voltmeter:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Using the meter if you test for continuity between C1 and A2 of the relay (not the wiring) and find it has continuity then the relay is stuck in the high on position, if it doesn't have continuity then it is almost certainly a short to positive in the wiring.

In this case we will want to check for voltage to both C1 and C2 wires (not the relay). Whichever wire has voltage will need to be traced back to the other end as shown in the diagram, looking for melted wires. The repair would consist of replacing the shorted wire however it is almost certain that there is another damaged wire that it is making contact with so it is very important to trace it form end to end to make sure the other wire it is making contact with also gets repaired.

Hopefully this helps you track down your problem. Please keep us up to date on your progress and thank you for using 2CarPros!