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Re: 97 gmc suburban heater fan only works on hi
Hello , it is located under right side of instrument panel , on heater housing . an extra clue is the wire connector going to it has a dark blue, a light blue , a tan and a yellow wire on its connector , you will only see the outside of the resistor as the actual resistors ago inside the heater case .and also this is 1997 gmc suburban , even tho listed under 1993 gmc suburban , same instructions . hope ya fix yer problem .
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Check your blower motor resistor for a bad connection or melted pigtail.It is located on the passenger side motor in the heat duct there is usally 2 screws that hold it against the heat duct.These resistors get pretty hot and melt the pigtail causing it to lose its connection.Perform the wiggle test on it with the ignition and fan switches on.You may need to replace the pigtail or the resistor or both.
I'm 99% sure it is the blower motor resistor - common problem. Pull the panel off the passenger
side under the glove compartment. You'll see the blower assembly on the right side with a multi
colored wiring harness going to it. Disconnect the harness and pull out the reisitor, it'll have a gasket going around it to protect it from moisture and humudity. I have replaced 3 on my 1999, but the last one, I wrapped electrical tape around the exposed resistor. Might be luck, but this one has lasted me over 2 years now. While you have the panel dropped, I highly suggest chainging the air filter located there as well. Your AC will run more efficient.
It is a 99% chance you need a new fan speed resistor board. It is beside the fan motor.... it sits in the heater/AC duct work to use the air flow to cool itself. It costs about $35 and takes 15 mins to change. Did you loose one speed then another and now only high works? That's the usual way they fail.
It sounds like your blower motor may be bad. I don't know if you know how to check power at your blower motor plug, but you can use a volt/ohm meter or a test light. If you have power (12VDC) , your motor is most likely bad. There is also a resistor block module which has 2 resistors on it. It controls the motor speed basically by restricting the power by directing it thru one of the resistors. The higher the resistance, the slower the motor turns, thus the 3 speeds for the motor. The resistor module is mounted on the blower housing and has 2 screws holding it in with a small plug connected. It is just about straight ahead of the passengers left knee.
You can get used motors from a junk yard pretty cheap.
I have a 95 suburban and it has a resistor module mounted to the heater plenum under the dash. It has a plug on the out side and 2 screws holding it in place. It is about 2x3 inches. It just looks like a flat plate on the outside. The resistor module has 2-3 resistors and it basically routes the power to the fan thru one of the resistors. The more resistance the slower the fan turns. That makes up the 3 speeds.
There is also a chance the motor is going bad and requires the full speed power to make the motor operate.
The resistor module is basically forward of the passengers left knee. If you know anyone with a meter, they could check it out for you.
If you have power at your motor plug on all 3 speed settings, chances are your motor is bad. You can get used ones from a salvage yard pretty cheap or buy a new one.
The fan switch itself is a possibility, but there is also a resistor
pack behind the glove compartment. Hi speed doesn't use the resistors,
though, so if it doesn't run on hi, it narrows it down to the switch,
the motor, the motor ground, or the blower relay, or any of the
associated wire connectors.