I have a 1998 Blazer 4 dr 4x4. The heat gets nice & hot, but when i turn the defrost dash floor selector, it doesn't seem to work all the time. It rarely goes to the floor, and it doesn't blow really hard out of the dash vents. What should i be looking for? Please help.

 

The actuator that controls the vents. It is under the dash and they usually do fail. All plastic with plastic gears.

 

Also for your air not coming out of the vents very good, the evaporator core can get clogged up with dust due to it sweating when you run the A/C. Pull your blower motor & check to see if it is clogged. Brake wash and some compressed air will clean it best at first then spray in some evaporator coil cleaner to finish it off.

 

It also seems that i get the drip like the a/c is o n, but with the heat on. The heat thing is also intermitant. The heat will be on & strong, then it stops blowing as hard and the diverter controller really doesn't do anything, then it will work again after several minutes.

 

could be vacume leak hvac vac line is by drivers side hood hinge if i remember. if it's 4wd look for trans fluid in vac hoses at back of intake vac switch on transfer case can leak atf . it will get all the way through the system ruin diaframs and actuaters

 

If i looked at the correct hose, it's dry rotted. The outer layer of hose was crumbling in my fingers. It's a small diameter hose that goes from the manifold to a connection on the drivers side by the hood hinge.

 

Also, my the fan is really loud on the outside of the truck. And, I get a drip like the ac is on. Why?????