2005 Vue AC compressor shuts off when Fan speed is 3 or 4

[JZVue]

My AC was recently repaired (two years ago) with new compressor, freon and so forth, so I know the system is in good shape. The AC compressor is shutting off when I move the fan speed above 2--it works fine in 1 and 2. The AC light does indicate what is going on with the compressor kicking in or out. It lights up in 1 and 2, goes out when I go to 3 or 4 fan speed. I can hear it clicking in and out. The fan does have all 4 speeds, so I don't believe it is the resistor pack. It seems to me the compressor thinks the fan is not running on 3 or 4 and shuts off. I am guessing the compressor gets the signal to run from the control panel which means the fan is running and the AC button is pushed. Anyone else have this problem? Maybe there is a enough of a voltage drop on 3 and 4 that no longer keeps the compressor happy?

 

[JZVue]

In case anyone is still reading these posts.... I replaced the AC/Fan relay, which is the gray cube shaped relay found in the passenger side fuse box (which is under the plastic panel in the center console). This seems to have helped. This relay is very common, especially in GM vehicles of this era.

 

[swesby]

I am faced with the same issue right now with my 2004 Vue. I looked into what you said about the AC/Fan relay. I took the relay out and jumped the sockets from the power terminal to the supply socket for the fan power supply. I then tested the result - no difference. I am now further testing and looking into this. I am leaning towards a module issue but have to do more testing. Perhaps you have new info on what you have on this.

 

[Derf]

That relay should not have its operation changed by the blower motor fan setting. The only thing I can think of is that the blower motor resistor pack is partially defective. When the blower motor is turned on and stepped through the different speeds, the speed of the motor is determined by the total resistance that the current experiences in the circuit on its way to the blower motor. Basically there are different voltage drops across different sets of resistors that end up determining how much current goes to the blower motor itself.

These modules are usually air-cooled and installed into the ducting itself. They are usually under the dash near the blower motor. I've always found them on the passenger side but I am not familiar with where it is in the Vue.

What must be happening is that speeds 3 and 4 on the blower motor are patched through to the position 3 and position 4 set of resistors. In each case, there must be an open circuit. Since this is all controlled by the BCM, I'm thinking the BCM sees an open circuit there and interprets it as the blower motor not being engaged. In which case the compressor doesn't need to run if the fan's not spinning.

Anyway, it usually comes out with two screws, and you can look up the part number for it at places like gmpartsgiant.com. highly recommend searching by VIN. If it is discontinued, there are still ways to acquire it.