So i notice some things have been happening and I don't know if this is normal or not but I don't think it is. First thing with the fan off, I turn on the rear defogger and I hear the ac compressor Come On. And that burns gas. Then if I turn the front defogger with the rear off the ac compressor still clicks on. Is that normal? Next when I turn the fan on sometimes it don't blow air then it starts blowing air again what could this be? Any opinions would be much appreciated

 

When using the rear defroster, I believe GM does intentionally kick the AC on for a moment.

As for the blower issue, sounds like the blower motor (under the passenger kick well) might be failing. Somethings a small tap with the handle of a screw driver can get it moving again (I had one on my old '94 Grand Am do that until I replaced the blower motor).

 

And now I'm confused because my shop said the rears isn't normal because it's on a grid it shouldn't be doing that if I turn on the rear by itself and not the fan. I also was getting mixed answers from the Facebook mcf and other monte carlo pages. Just hate that it eats ma gas

 

Here are some facts straight from the shop book:

Front Defrost Mode

If the HVAC system is in front defrost mode when you turn the vehicle off, the HVAC system will restart in front defrost unless the engine is off longer than 40 minutes. If the engine is off longer than 40 minutes, the system will restart in the previous operating mode set prior to using front defrost, with outside air being drawn into the vehicle.
When FRONT DEFROST is selected, the A/C compressor is activated and outside air is brought into the vehicle. Air will be directed toward the windshield with a small amount of air toward the side window outlets. Vacuum is applied to the mode actuator through the Blue vacuum line and to the defrost actuator through the Yellow vacuum line. The mode actuator will retract, closing the Vent Door. The defroster actuator will retract, opening the Defroster Door and close the Heater Door through mechanical linkage. Recirculation mode is not available in front defrost. The rear window defogger does not affect the HVAC system at all.



Rear Window Defogger Operation

Battery positive voltage is supplied to the REAR DEFOG relay switched input. With the engine running, the BCM supplies battery positive voltage to REAR DEFOG relay coil. When you depress the rear window defogger switch, the HVAC control module illuminates the rear window defogger indicator and grounds the control circuit of the REAR DEFOG relay. This energizes the REAR DEFOG relay and allows battery positive voltage from the relay switched input through the switch contacts and out the relay switched output to the REAR DEFOG circuit breaker to the rear window defogger grid. Ground for the rear window defogger is provided by G309.
When you start the engine and press the rear window defogger switch for the first time, the defogger cycle lasts for 15 minutes. Further operation results in 7.5 minute defogger cycles. The defogger cycle resets to 15 minutes when you cycle the ignition to the OFF position and then back to the ON position.
If battery voltage is low, the BCM will disable the rear window defogger by removing the battery positive voltage supplied to the REAR DEFOG relay coil.

 

ok so the front is normal, but im not sure if i comprehended the rear defogger option

 

The rear defogger has nothing to do with the A/C (including the compressor). Maniac, thanks for the info.

 

i wonder what i can do to fix this

 

with the fan try to replace the resister for it. I had a issue with mine before it did the same thing to be honest the first time. it is closer to the firewall beside the fan it has a small nut and a plastic nub holding it in. the easy way to get to it is have the seat out to give your self room so you can be on your back and reach with both hands to take out the old one and put in a new one.

 

another thing that is happening is that it takes a while for the heads up display to light up or the driver info thing where it shows the temp, what can be up with that?

 

Is the hud and the fan controls linked?