AC questions

[biochemist]

Hi fellas (posted on the GM-Tech forum also)...I have a couple questions/observations about my AC. I just tested with a thermometer in the middle vent...here is what I observed, I have the dual-auto setup BTW:

 

Temp and Humidity at the time of testing 80 F and 80%...quite sticky, cloudy...

 

Full fan, recirc, 60 degrees both sides...temp at vent after 5 minutes = 62 F

in auto mode ~ 60 F

 

While driving it will drop a few degrees to ~55 or so F

 

However, if I lower the fan speed to ~ 1-3 bars the temp can gets as low as 40 F, very chilly! Seems to put out cooler are at lower fan speeds.

 

Also, can you tell a difference when in recirc mode versus not...I sometimes hear something move in the dash area, but at high fan speed I cannot tell a diff. in fan speed or sound. It does cool better when that button is pushed though...

 

I guess I am not understaning how this system works...I typically to not use the AC, so I cannot remember how it was last year when new, but I thought I remembered it being a tad cooler. Not that it does not cool off, but at Max fan speed it seems to not be pumping out COLD air, just cool air...is the system functioning OK, I mean, it will go down to 40 degrees at lower fan speeds just does not pump that cold of air at max speed (all while not driving BTW)...While driving it seems to cool down a touch better, as expected though. I think the system is function OK as far as the auto goes, if I move up to 61 degrees it will adjust the fan speed and it will pump out hot air on one side and cool on the other, so that partioning function is fine...Last thing, even if it has been 100 degrees, it will pump out cool air almost immediatley after starting...so I am not sure, figured I would see what you guys thought. Thanks, later,

[BBSilverado]

Sounds normal to me.

 

The air will get colder when the fan is on a slower speed. The air takes longer to pass through the AC evaporater coil and in turn it cools down more than it would on high speed.

 

when to cab is really hot (from sitting outside in the sun) it is better to use outside air to cool the cab down first, (the outside air temp is probably much lower than the inside air) then switch to the recirc once the inside temp is less than the outside.