Front HVAC blower motor intermittent

[02Lightning]

I replaced my blower motor resistor, none of the wires look to have been hot. But the blower will stop for no reason, then start back up? The resistor didn't fix anything.

 

[Joseph Garcia]

My thought is that you have an issue with the blower motor. Is it possible that the motor is overheating and has an internal overload shutoff? Or, perhaps, the motor heats up with use and there is a failing winding that becomes disconnected with the heat expansion.

 

[Doubeleive]

I replaced my blower motor resistor, none of the wires look to have been hot. But the blower will stop for no reason, then start back up? The resistor didn't fix anything.

sometimes the motor can burn up the harness connector, the only way to tell is either unplug the blower motor harness and look at the tip with a flashlight or pull the blower motor out and look inside the connector and/or bench test. Had to replace mine it just stopped working because the connector was toast. replaced the plastic piece of the harness and grabbed a used motor out of the junkyard.
pulling the blower motor is easy. one screw and a locking tab to lift up and then it twist's out of its slot and comes down, hard to see up there use a flashlight to see what I am talking about.
NOTE: that there are 2 different versions of the blower motor, the early version prob 07-09 has a slot to get "air" cooled from the hvac box, and the later rmodels do not have the slot and are "self cooled" from the blower motor.
when you pull the motor you will either see a slot with a hole or not.

 

[02Lightning]

I'll look into the blower motor, thanks guys.

 

[Dustin Jackson]

@02Lightning I had a similar problem recently and I thought it was the resistor because when I smacked it the motor would come back on. It turned out to be the blower motor

 

[02Lightning]

I replaced the blower motor, we will see if that helps

 

[02Lightning]

Blower motor did not fix the problem, any other ideas?

 

[Doubeleive]

Blower motor did not fix the problem, any other ideas?

Blower motor resistor although I have not heard of any going out on this gen since they are considerably more beefy than they used to be on the gmt800's, however I have a spare I bought sitting in my tool box just in case, it's been sitting there for probably 4-5 years now.
yours would be the first I have seen, you might want to pull it out and see if it looks melted or anything they do have a big heatsink on them

 

[02Lightning]

Blower motor resistor although I have not heard of any going out on this gen since they are considerably more beefy than they used to be on the gmt800's, however I have a spare I bought sitting in my tool box just in case, it's been sitting there for probably 4-5 years now.
yours would be the first I have seen, you might want to pull it out and see if it looks melted or anything they do have a big heatsink on them

Well, I've replaced the resister and the motor and I still have the problem. No wires or plugs melted anywhere.

 

[Doubeleive]

Well, I've replaced the resister and the motor and I still have the problem. No wires or plugs melted anywhere.

well then that leaves either the controller or possibly a fuse is being wierd as joseph noted above with a possible motor issue, try new fuses first.
do you have a scanner? like a tech2?
is yours the manual control with big knobs or is it the digital auto control?
with the manual control I think it would be hard to tell if the whole unit is just loosing power, with the digital it has lights

 

[02Lightning]

well then that leaves either the controller or possibly a fuse is being wierd as joseph noted above with a possible motor issue, try new fuses first.
do you have a scanner? like a tech2?
is yours the manual control with big knobs or is it the digital auto control?
with the manual control I think it would be hard to tell if the whole unit is just loosing power, with the digital it has lights

The HVAC is auto, I do have access to a tech2 that I will have to borrow to see if it has set any codes. Pretty sure when the fan stops for a few seconds, both front and rear air stops. Problem is it's intermittent. I have also never heard of a fuse causing problems like that.

 

[Doubeleive]

The HVAC is auto, I do have access to a tech2 that I will have to borrow to see if it has set any codes. Pretty sure when the fan stops for a few seconds, both front and rear air stops. Problem is it's intermittent. I have also never heard of a fuse causing problems like that.

the fuse thing is just a thought, bad fuses can do bizzare things. had one once that looked fine but would only pass about 4v out of 12, others that looked fine passed testing on the top side but was still bad.
Intermittent issue's can be a real pain, when it cut's off is the temperature reseting to 74? or do you ever see it changing back to 74 on it's own?
anything else going on? flickering lights?

 

[02Lightning]

the fuse thing is just a thought, bad fuses can do bizzare things. had one once that looked fine but would only pass about 4v out of 12, others that looked fine passed testing on the top side but was still bad.
Intermittent issue's can be a real pain, when it cut's off is the temperature reseting to 74? or do you ever see it changing back to 74 on it's own?
anything else going on? flickering lights?

No symptoms, other than the fan turning off out of nowhere for a few seconds randomly. Makes me think a cabin thermometer going bad or something commanding the fan to turn off.

 

[Doubeleive]

No symptoms, other than the fan turning off out of nowhere for a few seconds randomly. Makes me think a cabin thermometer going bad or something commanding the fan to turn off.

the auto function does turn the fan lower/higher but whenever I have used it the fan speed change is suttle it doesn't just cut off it will slow down and speed back up as it adjust's or vica-versa. But I never use auto in the hot summer it just can't keep up good enough.
but it's another reason to look at the scanner data and see what the sensors are showing commanded-versus-actual
the one above your head and the one above the 2nd row passenger are the ones that detect cabin temp. the ones in the ducting probably wouldn't be a issue.
try turning off "auto" and see if the problem goes away

 

[mountie]

I tend to drive with my window open..... Sometimes the fan ( does what you mention).... It blows strong, then slows... strong again...
I wonder if switching the 'vent' to .. interior only? I think that solves it ?

 

[02Lightning]

Turning off auto doesn't help with the blower coming back on.

 

[02Lightning]

Noticed this the other day. Front fan cut off, the rear fan was still working. I tried to change the fan speed manually and got no change. Then after a few seconds the front fan kicks back on like nothing happened. Anyway, still having the problem.

 

[mikez71]

Starting to sound like the control module possibly?

 

[Doubeleive]

Noticed this the other day. Front fan cut off, the rear fan was still working. I tried to change the fan speed manually and got no change. Then after a few seconds the front fan kicks back on like nothing happened. Anyway, still having the problem.

have you checked the blower motor /harness to see if it looks burnt or anything? if you pull the blower motor out and disconnect the harness look inside the motor end of the harness for any burn marks and on the male tip that plugs in, had to replace mine because of this.

 

[02Lightning]

have you checked the blower motor /harness to see if it looks burnt or anything? if you pull the blower motor out and disconnect the harness look inside the motor end of the harness for any burn marks and on the male tip that plugs in, had to replace mine because of this.

I have looked at them, all look good. No traces of heat.