Any owners with CJ2 Automatic A/C...

[02 Silverado Z71]

I have owned my 2004 GMC Sierra SLT for about 7 weeks now. I have a few questions about the automatic A/C and heat system in the vehicle...

 

1. Why, when I have manually directed air flow to "heat" position, does the A/C compressor engage?? I thought the compressor should ONLY engage when you have a defrost mode engagaed OR when you ask for A/C by request. Compressor cycling when in heat position from floor?? WTF is that??

 

2. Hardly any response from the HVAC blower motor until I select a high fan speed by request. Say, for instance, that the heater control head displays a digital, 10-bar graph. Blower response is hardly anything until you select up to the 7th or 8th "display."

 

I know how automatic air conditioning operates; and I always over-ride it manually anyway. What's going on with my truck?? Is it screwed up or what?? Been like this from day 1.

[Shawn T]

I own an 03 and I have the same crap. The "automatic" is almost unoveridable. Even if you select the floor mode for manual, if the inside temp is above the selected temp it will blow A/C air on your feet. It sucks because there is no real manual controls. I have found if you want to manually run the heater you have to:

1. Turn the floor directional damper on

 

2. Turn the driver and passenger both to 90

 

3. Turn the fan on high

 

This will work until the temp in the cab reaches around 90 and then back comes on the A/C compressor. It's almost like the truck thinks it knows your body temperature better than you.

[02 Silverado Z71]

sstimothy,

 

Thanks for the response. Check this out:

 

48 degress outside today. I have the heater set at 85. I turn on the blower motor, manually. I STILL hear the compressor cycling! Something in the CJ2 programming??