A/C Fan Issue - speed up and down

[healeykit]

I hardly ever run my AC but had it on the other day and noticed a strange problem. With the fan on high speed it blows hard then drops off then resumes blowing hard. Completely independant of engine speed or if I was driving or stopped. While feeling around behind the fan speed knob I found the wires very hot to the touch after only about 5 minutes of operation so I shut it off right away since I don't carry a fire extingisher

It's the under dash blower unit installed in early cars.

Seems like an issue with the fan motor itself or an electrical problem. I was wondering if anyone has had this problem and how to fix it?

Thanks

[orange911]

my fresh air fan does sporadic speeds on its own, I no longer use it. I have a spare fan to try, but rolling down the windows work until I get enough time.

I have taken a couple of these under dash Behr panels apart and the a/c fan switch is covered in asbestos/foil material. I guess it can get pretty hot. Some the of the red wires when removed had streaks of black from overheating. If you know how, check the amp draw on the motor and see if you have a bad fan. Can't tell you how since I have never done it.

Olin

[edmayo]

This was a common problem, usually a combination of three. The add-on three fuse panel will get hot because it is overloaded which then loosens the riveted fuse terminal connections due to the excessive heat. The blower speed switch itself also goes bad for the same reason, and then finally the crimp on spade connectors to the switch get loose at the crimp and should be replaced with new connectors.