1993 2500HD 6.5L diesel
Although I can hear a relay click three times I only have one speed HIGH.
For about a day I had no blower running. So far now just high speed.
I can live with that but it would be impossible to drive with no blower in the winter, for defrost.
took off glove box and notice three relays...one clicks three times but
only one hot wire goes to blower. I wonder if this is a common problem.
I hate to take it to a dealer at 90 bucks a hour plus shop charges if it is a
simple replacement.

Just a stock truck with New process 5 spd. about 180,000 miles.
vr
amccom

It's either your switch or the resistor gone.

More than likely the blower resistor

On '99 - up, its a very common failure, but I don't know about your year

Take the resistor out and test it with an Ohmmeter. The reistor is for all but high speed. IIRC, it's located behind the glove box, in the top of the duct work.

1993 2500HD 6.5L diesel
Although I can hear a relay click three times I only have one speed HIGH.
For about a day I had no blower running. So far now just high speed.
I can live with that but it would be impossible to drive with no blower in the winter, for defrost.
took off glove box and notice three relays...one clicks three times but
only one hot wire goes to blower. I wonder if this is a common problem.
I hate to take it to a dealer at 90 bucks a hour plus shop charges if it is a
simple replacement.

Just a stock truck with New process 5 spd. about 180,000 miles.
vr
amccom

If my memory serves me right, i believe they just change the voltage on the wires to the blower. As mentioned check the resistor.

Take the resistor out and test it with an Ohmmeter. The reistor is for all but high speed. IIRC, it's located behind the glove box, in the top of the duct work.

If your year model is anything like the 99 - 03's, you won't even need to test it. Just pull it out and visually inspect it. If it is the POS printed circuit resistor, it will likely be all visibly burned/brown, etc. and that means its time to change

I just fixed the same problem on my 96'. Mine was a bad resistor, its located on top of the duct work, not very easy unless you have small hands. good luck.