Max AC slowly stops blowing

[Javier B]

Hey folks. My 95 Explorer has well running regular AC, but just this past week when I set it to MAX, it changes over and blows fine for a few seconds and then slowly something closes and no more air of any kind blows. You can feel something slowly closing as the air goes from blowing hard to just a little and then zilch. I was at first thinking something in the blend door or actuator there, but I get *no air at all* in the Max position after the first few seconds, so that didnt make sense to me (i mean, if the blend door was failing wouldnt I just get normal AC? Or am I wrong?). any ideas? Sorry if this has been answered, I looked around for AC issues but since I dont know what's broken I may not have searched for the right thing. Thanks

 

[1998Exp]

Hey folks. My 95 Explorer has well running regular AC, but just this past week when I set it to MAX, it changes over and blows fine for a few seconds and then slowly something closes and no more air of any kind blows. You can feel something slowly closing as the air goes from blowing hard to just a little and then zilch. I was at first thinking something in the blend door or actuator there, but I get *no air at all* in the Max position after the first few seconds, so that didnt make sense to me (i mean, if the blend door was failing wouldnt I just get normal AC? Or am I wrong?). any ideas? Sorry if this has been answered, I looked around for AC issues but since I dont know what's broken I may not have searched for the right thing. Thanks

It's not the blend door -- that one controls the temperature, not whether it's blowing or not. Are you sure it's not blowing at all, from anywhere? If so, a common cause is a bad blower speed controller (resistor), but if it starts and then stops, you may be dealing with a bad blower. If memory serves, there is a sensor that opens and cuts the current to the blower if things get too hot in the resistor box (which sits inside the air plenum) - a sign of lack of airflow, potentially caused by a stalled rotor of the blower motor. Try to hook the blower directly to the battery (for a few seconds) and see what happens. If it gets very hot quickly and/or doesn't spin fast enough, you have your culprit.

 

[Javier B]

Hmmm.... a perplexing update. went to troubleshoot this problem a bit more this morning and the AC is back to working fine and normal in both modes. >:-(
So aside from hurray it fixed itself, I'm still left wondering what the heck was going on and clogging the max AC. Maybe it was a hamster that moved on. I'll repost here if the problem returns. Nothing I hate more than *intermittent* problems.

 

[Javier B]

wouldnt a bad blower motor affect both the regular AC setting as well as the Max AC setting?

 

[1998Exp]

wouldnt a bad blower motor affect both the regular AC setting as well as the Max AC setting?

On MAX AC the blower gets maximum current, to make it run at full speed. If the problem happens again, try to turn the blower speed to maximum on regular AC setting. If it blows fine on that but not on AC, my speculation is wrong.

 

[Javier B]

So this problem has returned.
The blower does not seem to be the problem. I can hear the blower going full blast, and yet the airflow from the vents changes after about 20 seconds from full blow to a trickle to nothing, but the sound of the blower is still going strong. I have no idea where the air is blowing to, but not out of the vents. When I switch back to regular (*outside) air, it opens back up. Any ideas of what is closing and where in Max AC mode?

 

[tillerspet]

So this problem has returned.
The blower does not seem to be the problem. I can hear the blower going full blast, and yet the airflow from the vents changes after about 20 seconds from full blow to a trickle to nothing, but the sound of the blower is still going strong. I have no idea where the air is blowing to, but not out of the vents. When I switch back to regular (*outside) air, it opens back up. Any ideas of what is closing and where in Max AC mode?

I’m getting similar if not the same issue! I can hear it blowing like crazy, but I’m sweating buckets driving in this weather (and it’s barely begun!!)
ETA: actually, I can hear SOMETHING going like crazy but it’s NOT the fan! I opened the glove compartment and took a look. With the AC on MAX, this door opens and you can see the fan is NOT moving.

 

[Bjl8691]

Over the years I've had 2 blower motors blow then stop pop the hood give the motor a tap comes back on carbon dust from the brushes collects on the armature which caused intermittent function of the BM a shot of compressed air and a comutator cleaning stone solves the problem until the motor wears out

 

[tillerspet]

Over the years I've had 2 blower motors blow then stop pop the hood give the motor a tap comes back on carbon dust from the brushes collects on the armature which caused intermittent function of the BM a shot of compressed air and a comutator cleaning stone solves the problem until the motor wears out

Pulled over, banged the top, and voila! Working. Currently ordering the motor ANYWAYS since it’s over 20 years old.

 

[Bjl8691]

Pulled over, banged the top, and voila! Working. Currently ordering the motor ANYWAYS since it’s over 20 years old.

Cool glad your back in business