Emergency Brake Repair!! Yikes! Is it hard?

Hi. My 1997 Nissan Pathfinder 3.3L automatic is not blowing air into the vehicle on settings 1-3. Setting 4 works fine. Fuse intact Any suggestions?

I have a 1995 Ford Ranger pickup with a 2.3 L manual trans and 2 wheel drive. I changed the front brake pads and then separately had the rear brake drums, shoes and hardware changed at a shop. When I got it back there was a severe pulsing of the rear brakes when applied. I took it back and they put new drums on to eliminate that part of it. They were saying that they thought the rear axle was bent. Prior to bringing it in there wasn't any pulsing in the rear. In total they have taken all of the brakes apart and looked at them three times and said there wasn't anything wrong with the brakes. When I drive the truck I can hear a rubbing (not continuous, more like a rub every half wheel rotation) on the drivers side. Looking at the wheel shows that there is a slight wobble but not much at all. When the brakes are applied there is a severe thumping or rubbing and it seems like it's coming from the rear. If the axle was bent wouldn't the truck shake when I drive it? It rolls down the road very smoothly. How can I make sure the axle is straight or could it be that the bearings on the axle are wearing? How would I check for bearing wear? I tried pulling on the wheel to check for loosness or wobble but both wheels seem OK. I'm at a lose and don't know what to do. Any help would be appreciated.