Questions and Answers

GMC Van Blower Motor Q. Hello Mr. Ciulla: I have a 1989 GMC Vandura 2500 with a large V-8. The A/C heater blower motor seems to peter out after about an hour of steady highway driving. For example, it worked fine yesterday (using A/C) during a one hour drive, but on the return trip, when I moved the switch from Off to High, I got only a trickle of air from the vents.

I parked the van and listened to the blower motor, it responded to the different switch positions, but still only put out a trickle. I started the van the next morning, and voila, the air blasted out of the vents as if nothing had happened.

This problem also seemed to occur when using the heater a few weeks ago, though there is a slight chance I just had the vent control lever in the wrong position.

I replaced the relay that sits on the plastic A/C housing but there was no change. For what it's worth, I had the freon converted a few years ago. Also, I assume it's normal for the metal A/C parts to accumulate heavy 'frost' during operation. Thanks in advance for any suggestions you might have.

Best regards,
Scott

A. One of two things is happening here. 1. possibly something is inside the ductwork and blocking airflow, like a plastic baggie? 2. In A/C mode, if the thing is getting too cold, there can be ice forming in the evaporator core and blocking airflow. When the ice melts after shutdown it flows okay until it freezes again.

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