AC trouble 2004 GMC Canyon?

?Pretty? ?Kitty?

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The AC suddenly will only blow on high. The other settings are dead. Air is cold but the fan won't work except on high setting? What could it be and about how much should it cost to fix? Warranty is over.
 
It's not quite as simple as just the blower switch. The blower speed selection is supplied by the hvac control module. You have to replace the entire module to replace the switch. On high speed the module supplies a direct ground circuit to the blower motor. On the other speeds, the ground circuit is supplied through resistors. OEM list price of the module is $376.09, pays .6 hrs. to replace.

Check the resistors first.
 
Sounds like a blower resister assembly. Unplug it, located near the blower motor and check for voltage one wire at a time while changing the switch positions. This will confirm it.
 
Your problem is a bad blower resistor. Shouldn't cost much at all. If you can locate it, you can replace it yourself. All you have to do is unplug it and remove two screws. It's located in the heater box right next to the blower motor. It should have a plug with 4 wires. Normally, this is under the hood on the firewall.
 
Before replacing the switch, check the blower resistor. When the thermal diode goes out, it will stop working. But for safety reasons, the high blower speed doesn't go through that, thus you will have high fan only. By safety I mean lack of defrost for vision.
 
It sounds like the switch went bad, there easy to replace and cheep, it should pop out of the dash and then plug the new in, go to the dealer and look at the new one before you buy it and ask how it go's in, that would give you a better idea of what to do. Good Luck and GOD Bless
 
It sounds like the switch went bad, there easy to replace and cheep, it should pop out of the dash and then plug the new in, go to the dealer and look at the new one before you buy it and ask how it go's in, that would give you a better idea of what to do. Good Luck and GOD Bless

hi there buddies sorry for lurking in this old thread. but i am experiencing the same problem and my mechanic told me it is the switch but there are lots of switch i dunno which switch. there's AC thermo switch, ac temp switch, ac switch. if it is the blower resistor looks like it's time to change mechanic.

asdahttp://www.autopartswarehouse.com/a-fs-c_thermo_switch~pop.html
 


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