When I leave work and turn the AC on after about 10 minutes of city driving the blower fan slows way down to where it does not feel like it is blowing when I give it gas. When I left off the gas the fan speeds back up.

This happens in town, on freeway but never when you first turn it on.

What could it be???

The volt gauge does not drop.

 

To clarify, are you saying the blower motor RPMs drop or could it be the air flow is dropping? Vehicle info? There are several solutions depending on which symptom(s) you have. Just a little more info, please.

 

It turns out to be a vacuum problem. Driving it today I can hear the door drop and air comes out the floor when giving gas.

 

Great. Glad you got it diagnosed and I hope it will be a cheap fix. Those vacuum lines in the engine compartment fall apart over time.