2nd Gen Non-Engine/Transmission AC Question

[Bunyan]

I've replaced everthing but the evaporator core which I plan to replace this fall/winter so all is new. The ac will cool to 38/40 with the blower fan on low or low medium in recirculate or normal modes. As soon as you increase the blower speed to medium or high the temp will increase ten - twenty degrees. Any suggestions? From the time the truck was new through 2009 the ac would freeze you out no matter what the outside temp. I've talked to everyone I know and read all the information I could get my hands on with nothing stating how to correct this problem. Thanks for any help, Bunyan

 

[DieselDoghouse]

38 - 40 degrees is pretty cool (literally) as my manual specifies 55 degrees as an endpoint. Now, since the temp rises with increased airflow, is the evaporator blocked? Perhaps the increased flow is bypassing the core somehow and not getting cooled? When I had to replace mine the lower third was a compost pile since our air intakes aren't filtered

 

[B.G. Smith]

Did you have a compressor failure and if so did you change the orifice tube and the receiver/dryer? bg

 

[Missouri Mule]

I was reading in the Owner's Manual or the Factory Service manual that when you increase fan speed that the tempature will rise (or lower if you are using the heater). But 20 degrees would be a big difference.

 

[Bunyan]

Did not have compressor failer. Replaced all componets except evaporater. The rise in temperature is when the ac is on. Thanks

 

[B.G. Smith]

How fast is the clutch cycling on and off? Have you checked the pressures while AC is runing? bg

 

[Bunyan]

Clutch stays engaged always. I had the system checked and all is fine. I can't remember what the pressures were, but are within the limits stated in the service manual. No debris in the evaporter housing that I could tell. Flushed the housing with water while shop vac was sucking drain hole. I've been thinking there may be to much freon in the system. When they filled the sytem at the dealer its done with a snap-on self contained unit, not with gauges. My brain hurts from trying to get this straight.



My brother has an 03 and it cools fine. I've also checked trucks of friends while riding and they very a few degrees, but most are cooling at 45 degrees and max. I now have a hole in my wall from pounding my head against it. lol

 

[B.G. Smith]

I can understand your frustrations with the heat we have been having. Only other thing I can come up with is maybe the blend door is loose and moves when you turn up the fan. The water from engine circulates through the heater core all the time and the blend door mixes the air across the evaporator and heater core to control the outlet temperature. From the symtoms you give, it sounds like the AC is just cooling a minimum amount and when added air is introduced it can't cool that amount of air. That is why I asked in earlier post if the orifice tube was changed. bg

 

[Bunyan]

I can understand your frustrations with the heat we have been having. Only other thing I can come up with is maybe the blend door is loose and moves when you turn up the fan. The water from engine circulates through the heater core all the time and the blend door mixes the air across the evaporator and heater core to control the outlet temperature. From the symtoms you give, it sounds like the AC is just cooling a minimum amount and when added air is introduced it can't cool that amount of air. That is why I asked in earlier post if the orifice tube was changed. bg

I checked the blend door and installed a new motor on it and it seems to work fine. I also clamped off both heater hoses after truck sat over night and made sure no hot coolant entered the heater core. It did excactly the same thing. I thought maybe it did not have enough refrigerant so I added a half can and the temp went to eighty and would not cool below that point. I let some out and now its cooling as mentioned above. Thanks for all the help. Maybe we'll get it figured out soon.