Now that it's nice and warm out, I like to blast some AC. However, it seems that whenever either I or the system sets the fans on max, the fans will cut out, then go back up to max, cut out again, and repeat. If I take it down one notch, it operates fine, but on that max setting it keeps cutting out.

The same thing happened in the winter when blowing heat, as well. Any time it goes to max it repetitively cuts out. I haven't been able to find any info on this but hopefully someone has an idea.

 

Maybe the blower motor resistor pack?

Sounds like it is either full of dust and lint and is heating up and shutting off, or just going bad...

 

One thing I'd verify first is to listen carefully and make sure that the speed of the blower is indeed changing. It could be the recirculation blend door getting wonky and opening and closing which would just be redirecting the air to different areas which might almost sound like the speed changing. That will definitely change the sound and airflow if that is what is happening. Unfortunately that particular blend door is the most difficult and painful to get at and replace.


Another is maybe there is some leaves and other junk in the fan and when it tries spinning full speed maybe the extra load freaks the climate control out?

When I got my 03 one of the things I did was I pulled the entire cowling off and once off you can get at the top of the blower wheel on the upper passenger side. Surprised me to find a bunch of leaves and stuff sitting in there. I don't "think" it would have been enough to really bother anything though. But regardless, not much should, but apparently some crap can get into there.

Or of course as mentioned, the blower motor controller/resistor pack followed by the climate control panel itself.

 

It's definitely going to full off. It gradually goes back up again, but even off auto, if I set it to 100% in any way it cuts out.

I read up on the blower motor resistor pack thing and that seemed to have different symptoms. I'm still left scratching my head. I'll tear the dash apart some day maybe. Was just hoping someone had an idea before I went through that process.

 

I know its been a long time but did you ever figure this out? I'm having the exact same issue

 

check the fan harness to see if it has bad contacts and drop the fan and see if it spins freely? maybe it needs some oil on the bearings. maybe overloading the module or the harness.

 

I have a brand new blower motor and had my blower motor resistor remanufactured. My A/C was completely out of freon (again) so my mechanic put dye in it this time, it must have a really slow leak somewhere. My other issue is that the fan, only on high, and only when the A/C is on, will cut in and out over and over. All the other fan speeds work fine, and the fan works on high when using heat. Its really unusual. Does the high speed of fan run differently than the other speeds? Different relay or fuse? Is there something I'm missing? I really don't understand why it only happens with the A/C running but not on heat, or any other speeds.

 

hummer_on_fumes your issue really is a curious one.

The control of the "Blower Motor Control Processor" (resistor) is actually straightforward and done by single-wire 5V control-signal going into the module, nothing complicated.

The control-signal is pulse-width-modulated at 35Hz, at zero speed the signal sits at 5V (unmodulated i.e. HIGH) and the motor will be OFF i.e 12V on both sides of the fan's connector.

As the HVAC fan setting is increases, the control-signals "OFF" time increases, and the voltage across the fan increases (its kind-of "upside down" signal-wise)

You should be able to measure the control-signal and fan with a multimeter set to DC Volts, it may depend on the model of meter, but its worth a try and easy to do.

The table below is the correlation between HVAC Fan Setting, Control-Signal and Fan volts as measured in-vehicle.
For the control-signal measure across 0V (GND) and the input signal wire, for the fan measure across the fan connector (not to GND)

HVAC Signal Fan
Bar OFF = 5.5V 0.0V
Bar1 = 5.2V 2.9V
Bar2 = 4.9V 3.8V
Bar3 = 4.5V 4.4V
Bar4 = 4.2V 5.8V
Bar5 = 3.8V 6.4V
Bar6 = 3.3V 7.1V
Bar7 = 2.4V 9.6V
Bar8 = 1.4V 13.6V

I suspect you will find that at Bar8 you will see 1.4V which means it is modulating correctly with minimal ON Time, but the Fan Voltage will go to zero.

If so this is indicates there's probably something wrong with the "Blower Resistor" either over-heating or corrosion of it's PCB circuitry affecting it's operation (there is a YT video I believe)

If the control-signal goes HIGH (5V ish) then it is not being modulated so it must be the HVAC (unlikely)

That's the best I can think of...

 

hummer_on_fumes did you fix your problem?

 

it's been raining like crazy, going to try to work on it later this week. Thanks for your reply. I will update if I get it figured out for anyone else who searches this issue like I did.