After reading all these posts on the resistor/connector problems, I have been running my AC fan on 3 and adjusting the comfort level with the the recirculate and the temp. control. It is probably good to exercise these functions anyway. Just did a 5 hour roadtrip and stayed comfortable. Under my extended warranty I still have bumper to bumper for another 5 years and 100k miles but why take a chance. Going to the dealer is a pita.

 

Yes, the resistor is suppose to get hot. The resistor is resisting the current flow to the fan motor to make it run at the other speeds. The resistor is actually made up of three resistors. Each one has a different value to give you the four different speeds. Speed 4 uses no resistor to give you HIGH speed. Each of the lower speeds uses a resistor just for that speed. LOW or number 1 speed is the slowest and the highest value resistor. It gets the hottest and produces the most heat. Yes, the blower cools the resistor being inside the air duct. Number 1 speed produces the most heat, the blower runs the slowest and this is why it fails at this speed the most. The resistor connector conducts heat from the resistor out to the connectors, outside of the blower duct. If these connector aren't 100% tight and conductive, they will start heating up and destroying the connector. This happens to 99% of the Hummers out there. It is a bad design for such an exclusive vehicle and should have had a PWM fan speed system instead. Maybe I will work on one to use as an aftermarket add-on to end these problems. Anyone interested?

 

when you know,and they dont know, you dont tease to show what you know,i know what you know but you should tell the 97% who are not involved with the concept, just what pwm iz!

 

Check out:
Pulse-width modulation - Wikipedia, the free encyclopedia

 

Thanks so much for the info. It makes me feel better knowing this is normal (For at least our vehicle). I was just curious as to the gage of the wire being used in the harness. Any idea?

Thanks again.

 

Ok, sorry, I guess I should have explained my comment on PWM fan control that should have been on all Hummer vehicles.
PWM stands for Pulse Width Modulation. It is controlled by a small simple controller that "pulses" the electricity to the fan motor. The controller sends a signal to an electronic switch that can handle the current flow of the fan motor. The amount of time that the electricity stays on is called the duty cycle. So to give the motor a low speed, we would pulse the electricity at something like 10% duty cycle. Meaning it is turned on 10% of the time at a frequency of something like 30 or 50 times per second. The frequency can remain constant and we only adjust the duty cycle. For a full speed fan, we would take the duty cycle to 100%, keep the power on constant. This kind of fan control system means you could have an infinite number of different speeds on the fan also. However, I would set it up to match the Hummer control with 4 different speeds, something like 10% for #1, 30% for #2, 60% for #3, 100% for #4. The beauty of this system, is there is no resistor to get hot. Really all we are doing is turning the power to the motor on and off to control the speed. This is undetectable because we are switching it so fast (30-60 cycles per second.)
This just scratches the surface, but I hope it helps someone.
Craig

 

Yes, the blower does keep it cooler. That's were the bad design comes in because on the lower speeds there is more ressistance on the resistor which creates more heat and your getting less air blowing on the resistor. I always run my blower on #3 or #4 for less ressistance on the resistor and I regulate the temp in the H3 cabin by moving the vents or adjusting the temperature ****.

 

The problem is not the resistor overheating. Nobody has fried their resistor. It's the poor contact between the male and female spade connectors which adds additional resistance causing arcing and heat build-up which in turn melts the connector. That's why the issue is resolved when you solder the wires in place....positive connection.

 

wrong,,,as resistance is increased,power dissapated goes down,heat goes down.
i did a quik calculation using some assumed resistances just for calculation purposes.
these are not actual.
use 4 ohms for motor, then add 2 ohm resistors one at a time, 2,4,6 and u find;
motor full =36 watts.
all res=10 ohms,= about 14 watts, spread over the 3 resistors,and the motor.
actual values will be different but the results will be the same.

RIGHT

one way to look at this is; if the resistor were infinetly high,there would be,,,ZERO current!!,,no heat

 

Mines Doing the same. Blower stopped about a week ago. I disconnected today and sure enough.. same burnt resistor. I will try the fix and post update when completed. Thanks for the great post guys... hot in Florida.
07 Hummer H3 48,000