Both Electric Windows going up in hops

Suddenly both electric windows started going up in hops on our '92 Pontiac Trans Sport SE.

If you leave it for 5-10 min. it would resume normal operation then it freezes again in a few seconds and so on.

Any idea on what could cause this weird behavior in both windows at once & what we can do to fix it?

Note:
- window buttons (left and right) checked-out ok
- driver window motor was changed an year ago - it doesn't have the same wear as the other motor
- both window lift mechanisms and guides are properly lubricated and work smoothly

The fact the BOTH have started this at same time puzzles me....

..there is an electronic "load limiter" in each windows ...that cuts 12v feed if the motor is overloaded for some time...but that does not seem to be the prolem here.

http://www.avigex.ca/xport/pwrwindows.jpg

..I'd suspect some contact common to both windows deflects from heat under load ..... in fact the circuit breaker (thermal) is possibly out of spect....swap it with an adjacent breaker...under/behind glove box....at the convenience center.

http://www.avigex.ca/xport/convenience_center.jpg
http://www.avigex.ca/xport/convenience_photo.jpg

NOtice in my case the pwr window breaker is missing as I have rerouted the window circuit to the pwr seat circuit so it works with ign key off....

I will come with more later as 2 days ago my passenger window stopped working.....will look into that soon.....

Very good info. Thank you LMP!

I think that circuit breaker is most probably the common cause for this since both windows started to have this issue at the same time.

Will try swapping it with another circuit breaker and see where that leads us.

Many thanks for a most helpful advice!

Replaced the Circuit Breaker - no result - windows will go up the same.

We bypassed the master switch and powered a motor directly from the battery - same behaviour.

It must be that the mechanisms/window guides are making these motors work too hard & they are cutting out.

Will go about lubricating the whole vindow guide and see if that brings any noticeable improvement.

My 96 did the same thing on a rainy day. I replaced the motor and it works fine. The wrecker asked me if I knew it was the motor and not the relay. As I learned the relay is the cris-crossed arms that move the window up and down. They were fine and it was the motor.