A/c heater climat control switch

the heater works from hot coolant flowing through it so if it stopped working but was working recently , the problem will be in the heater control tap not turning on ( control module )
the blower works of electrical and trying to blow air indicates a problem in the fan speed control ( again a control module module)
if you have a climate control system in the car It may be the climate control module that is faulty as it controls both

Sounds like your controller is bad. http://www.resistorguide.com/applications/blower-resistor/ <Read this info.
http://www.ebay.com/itm/88-94-GMC-CHEVY-TRUCK-CLIMATE-HEATER-CONTROL-93-92-max-SILVERADO-SUBURBAN-SIERRA-/381127684906

hi,

found this for you..

https://www.2carpros.com/questions/gmc-jimmy-1996-gmc-jimmy-heater-blower-motor-not-working

Almost sounds like your climate control switch is bad as it controls everything including the switching and blower speed with the exception of the blower speed being a blower resistor issue (allows multiple speeds).

When the blower works only on the high setting its usually a bad blower resistor which is right near the blower motor. now you say it would always blow high regardless of the fan speed setting that would indicate probably the climate control unit or a connector problem somewhere. finally it not working at all may be the climate control unit or connection went bad even further. it might have a blown fuse or a bad blower motor in addition to the climate control unit or connector problem .check for power and ground at the blower motor. the power is supplied from fuses and may have a relay also. the ground is supplied from the climate control unit and goes through the resistor to control the fan speed. good luck

I replaced the fan module under the glovebox on my 2005 Town & Country last night. Mine would not shut off at all with key on. It only blew on high no matter where I set the switch. Mine also had the climate control which makes a difference. If it is not the auto climate control it is usually the blower resistor if the other fan speed selections don't blow at all except on high.

This is very likely a bad blower motor resistor. When this resistor goes bad you have only off or high. I hope this helps.

There is a plug up under the glove box that loosens and you need to snug it up.

this problem is caused by the blower motor speed control resistor being defective, it is located next to the blower motor.

If it is manual climate control.
You have a bad blower motor resistor. To replace it remove the lower dash panel cover below the glove box and it will mount in the heater housing with 2 screws. It will have a 4 wire connector with the wire colors being OG/BK,LG/WH, YE/RD, BK
If it is electronic climate control then you would have to replace the blower speed controller which is also located in the same place.