Question about AC compressor cycling

[Boomer Vibe]

Does anyone out there know the settings in which the AC compressor cycles on an 08 base Vibe? I was under the impression that it only cycled when the AC switch was on, when the switch is set to defrost, and any time the recirc button is engaged.My Vibe will bog down cruising down the road at normal speed 55 - 70 , not accelerating or decelerating, flat road, cruise not on. It happens at normal operating temp. About every 5 - 10 minutes, the engine will bog down for 10 - 15 seconds, then return to normal. I thought it felt like the AC compressor is engaging and disengaging, but all of the switches were off, and the knob was set to dash vent, and the fan switch was off. I then thought it could be an electrical load on the alternator.Since it is still under warranty, I took it to the dealer and explained what it was doing. The service advisor (I hate talking to these guys) said he would have the tech take a look at it. I picked it up later that day, and the service advisor said the tech told him it was just the AC compressor cycling. When I told him again that all of the switches were off and not on defrost or recirc, he said the tech told him the compressor can cycle at any time and is not dependant on any switch or contol dial setting.Does the service advisor or tech know what they are talking about? Has anyone else felt the bogging down as described? Any other thoughts on the cause???

[vintagegz]

normally if the fan is switched OFF then compressor will not cycle, check the service manual for schematic but this is normal in most cars.

[2002sportside]

If the switch is off, the compressor will not cycle. I will look at the wiring diagram later, but that makes no sense. Sometimes I just love dealers... talking to service advisers is just useless.My compressor does not come on with defrost though...

[Boomer Vibe]

Yea, I always thought that when the switch was off, that the power would no go to the compressor clutch no matter what.So if it is not the AC compressor cycling, what could cause the engine to bog down?It possibly could be a high electrical load coming on to the alternator - I thought maybe the electric cooling fan....Or could it be a glitch in the engine management software???The dealer just says they all do it. AAARRRRGGGG

[2002sportside]

Well since the ECM controls the AC relay, a glitch in that could be causing it to cycle for no reason. Thats a bit of a longshot though...Radiator fan could cause this, but at speed it wouldn't usually come on.Are there any other dealers in your area?

[djb383]

The next time it does it, try pulling over, popping the hood and feel the low pressure a/c freon line. If it's cold and wet, the a/c compressor is, or has been, engaged.

[jake75]

I got a call from GM today welcoming me and doing a brief survey on my satisfaction with the '09. They told me to call 800-762-2737 if there was ever any problem that couldn't be resolved by the dealer. A long shot - but there it is.