probably hvac mode door stuck (foam or other) or mode door actuator broken - (cheap plastic) - this is an ugly job - find someone who has removed the dash in this type of vehicle before - set aside 300 bucks or more :(
Answerprobaly just needs a blend door acuator.gmjim
ANSWER
Air door controlled by the red and blue vac lines is broken (common fault). Default position is with all air going to defrost vents. See Edmunds.com forums for GMC climate control problems for more help.
AnswerI own a 98 Chevy S10 that is exactly like the Jimmy (just different body styles S10 being a truck and Jimmy an SUV). I had a similar problem to yours, I was barely getting any air from my vents. I fixed it by flushing my coolant system with a flush system I bought at wal-mart that used an ordinary water hose to flush the system. After the flush my heater not only blew air better, but it got hot faster too.
I have owned two mid 90's GM S-10's with this problem. If you can hear the sound of air whistling behind the vent mode selector knob (sound varies as u torn the knob) your problem is there. The selector knob actually routes vacuum thrue the back side by opening and closing small passages on the back side of the knob. The rubber gets old and dirty and begins to leak. Replacing this switch was the cure for me. Or if you like to tinker and u r sharp, take it apart and clean it.
my 1998 gmc jimmy has no floor heat but i have defrost and ven heat
it won't stay on if your blowing it the floor or using defroster.
should be on floor.
on the floor on the floor
No, you should not, as the floor can be easily damaged.
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Your condensation line is stoped up. You can clean it out by using an air compressor blowing from the inside of house out.
in the floor.
The Heater core on your 1997 Jimmy is on the passenger side inside the cab, but it is behind the black plastic close the floor, and very difficult to get at.
no.
This problem can be an expensive one to fix because the whole heater box has to come apart. There is a plastic "hinge" that controls the opening and closing of the door. It is easily broken and jams up. The whole assembly has to be replaced. It's not an easy fix.
You should not buff a laminate floor.