What part do I need?

[noles401k]

My 2000 Monte Carlo AC is acting funny. When I turned the knob to setting 1 or 2 nothing would happen, but 3, 4, and 5 worked fine. Now this week 3 and 4 have stopped working and only 5 works. Anyone know what part this is that I need to replace?

Thanks

Chris

[EdTee]

It sounds like your heater blower motor is drawing excessive current (probably due to a bad bearing) and this caused it to burn out your blower motor resistor assembly. If you just replace the resistor assembly you stand the chance of burning it out again. The reason that the motor still works in setting 5 is that 5 enables the blower motor relay that bypasses the heater resistor to allow blower to operate at full speed. My suggestion is to remove and replace the resistor assy (dealer part) and the heater blower motor ($99 aftermarket/ ~$250@dealer).

[noles401k]

Hi Ed,

Thanks for your reply. Couple of quick questions if I may.

You mention heater a lot in your suggestion. Does it matter that this happens whether I am using the AC or the Heater or is that insignificant here?

Also, does this take into account the fact that this happenned gradually? Remember settings 1 and 2 didnt work for quite a while but 3, 4, and 5 worked fine. Only this past week did 3 and 4 stop working as well, leaving only 5 operational. Does your bad ball bearing idea still work with this in mind?

Thanks,

Chris

[EdTee]

Absoultely, the knob with the 1-5 is the Fan switch. It controls the speed of the "heater blower". This blower is common to both AC and Heat. It is just an electrical fan. The way they slow down the fan on settings 1-4 is with resistors with different values in the resistor assembly. The higher the resistor value the slower the motor goes. The excess power is dissipated through heat off the resistor. Since the fan slow speeds (1 & 2) have the higher resistor values a worn fan motor will cause excess current to be applied to the resistors eventually burning them out. I bet the majority of time you use settings 1 & 2 like I do. Only when they stopped working did you use 3 & 4. By the way, the blower motor resistor assembly is easy to get to and is located under the passenger side dash behind the glove box next to the blower motor. You will need to remove the panel under the glove box first. When you look at the rear of the blower motor, the resistor assembly is at the eight o'clock position. A cable harness is plugged into it and the blower motor cable also. One other thing, something that may have contributed to the current situation is the Cabin Air Filter. If it is clogged, excessive strain would have been put on the heater motor. The filter should be replaced every year or two depending on the dust/dirt environment.