Montana van 2002 why the fan speed control switch for heat and air only 4&5 but it is not working on 1,2 and 3 ???

Check and replace fan switch control module located in glove box...$30. part. Do it yourself.

check the blower motor resister

no sounds like u have a switch problem :) i would reccomend replacing the switch... Hope this helped

These fans should turn on at about 220 degrees, give or take a couple, and then turn back off at about 210 degrees.Fans should also come on when engine is idling with the a/c on [provided the a/c works of course] If the fan[s] isn't running and the gauge is over about 3/4 of the way or will go all the way to the end then odds are your fan's aren't capable of working for some reason. The classic symptoms of a cooling fan not working are what you are describing: Cools fine at highway speeds, overheats at slow speeds. I would start by checking the cooling fan fuses located in the underhood fuse panel. I believe they are marked Cooling fan 1 and Cooling fan 2 and both should both be 30 amp fuses. If the fuses are good then you might have problems with the fan motors themselves. Hope this helps you get it working again!

Clock Memory Fuse 8 and Digital Clock Fuse 6 .
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A/C Compressor Clutch Fuse 17
A/C Heater Control Switch Fuse 17
A/C-Heater Mode Switch Fuse 9
Air Bag Diagnostic Monitor Fuse 7
Air Bags Fuse 5
Amplifier Fuse 11
Autolamp Dual Coil Relay Fuse 4
Backup Lamps Fuse 5
Blower Motor Speed Controller Fuse 17
Clock Memory Fuse 8
Courtesy Lamps Fuses 6 & 8
Daytime Running Lamps Fuses 5 & 10
Digital Clock Fuse 6
Digital Instrument Cluster Fuses 5 & 16
EATC Blend Door Actuator [1] Fuse 17
EATC Blower Motor [1] Fuse 9
EATC Control Module [1] Fuses 5 & 16
Exterior Lamps Fuses 4 & 15
Flash-to-Pass Switch Fuse 10
Hazard Lamps Fuse 1
Heated Oxygen Sensor Fuse 5
Illuminated Entry Fuse 5
Illuminated Entry Module Fuse 8
Instrument Illumination Fuse 13
Keyless Entry Fuses 5 & 8
LCD Dimming Relay Fuse 6
Lamps On Warning Fuse 4
Lamp Out Warning Fuses 6 & 15
Liftgate Window Defrost Fuse 6
Liftgate Window Washer Fuse 6
Liftgate Window Wiper Fuse 6
Light Sensor/Amplifier Fuse 18
Low Oil Level Relay Fuse 18
Main Light Switch Fuse 6
Manual Lever Position Sensor Fuses 5 & 10
Mobile Telephone Transceiver Fuse 11
Police Accessory Relay Fuse 6
Power Antenna Fuse 11
Power Mirrors Fuse 8
Power Windows Fuse 6
Radio Fuse 11
Radio Memory Fuse 8
Rear Window Defrost Fuse 5
Redundant Radio Control Fuse 11
Shift Lock Actuator Fuse 5
Speed Control Amplifier Fuse 6
Speed Control Deactivator Switch Fuse 1
Stop Lamps Fuse 1
Transmission Control Switch Fuse 18
Turn Lamps Fuse 1
Turn Signals Fuse 5
Variable Assist Power Steering Module Fuse 5
Warning Chime Fuse 6
Warning Chime Module Fuse 18
Warning Indicators Fuse 18
Windshield Wiper Control Module Fuse 2
Windshield Wiper Motor Fuse 2.
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this will help.thanks.

check the blower motor resistor that is where the different speeds come from

COULD BE THE FAN SPEED SWITCH. IF IT RUNS ON ONE SPEED ONLY THE SWITCH IS MORE THAN LIKELY BAD.

Call your local GMC Dealer and see if they have the climate control panel in stock. What happens is the circuit board on the back of the panel shorts out. The panel comes as an assembly and is very easy to replace. Don't go with a wrecking yard piece. I made that mistake once and it didn't work either. I got one from the Chevy dealer and it worked perfectly.

are u saying u replace the switch on the climate control
cause it would be the resitor on the blower causing it