Automotive Air Conditioning Information Forum (Archives)

agood1 on Fri May 27, 2011 10:13 AM

Year: 2005
Make: Dodge
Model: Ram 2500
Engine Size: 5.9
Refrigerant Type: R134
Ambient Temp: 77

I'm having trouble with the AC in my 05 Dodge Ram. It weird, it is nice and cold for a while then gets warm and then cold again. I had all the freon removed and found there was 2.2 lbs in it, and it calls for 1.14 lbs. So we re charged it with the proper amount. Now the passenger side vents are about 10 degrees warmer than the driver's side. So I started adding a little more freon at a time and checking the temps. I got it cold but it will not stay that way. With my gauges on it....and the high side moves between 170-190. The low side keep fluctuating between 17 and 30. When it is down below 20, the air inside is very cold, when it goes up, the air inside warms up a bit. What would make the pressures fluctuate? About 77 degrees outside temp.

GM Tech on Fri May 27, 2011 10:49 AM

What is compressor clutch status when warming? Is it off? If so, cycling systems do this and it is considered normal operation. Other than that an active TXV.....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

ice-n-tropics on Sat May 28, 2011 4:22 PM

My 2005 Ram has a refrigerant label on top of the crossmember in front of the radiator which says 1 lb 10 oz on gas engines and 1 lb 14 oz for diesel
Suction and discharge pressure will hunt/vary with condenser puller fan cycling. I'm considering adding a pusher fan in front of the condenser for faster cool down.
Refrigerant control is orifice tube
hotrodac

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Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
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