A\C Problems

[jffmaz]

Sounds good. I usually check pressures and cycling at 1200+ rpm on my CTD. Probably why it wasn't cycling at 700 & 84*. My truck is a 98, fill is 32 oz, but yours may be different. Nice to have Ice Cold AC! Especially here in AZ! Enjoy!

 

[petersonj]

I put 36 ounces in total. Max air, doors open center vent had the thermometer. Ambient temp about 84. Yes, staying around 30 psi on the low side when not cycling. Compressor was not turning off, ran constantly on Max A\C. All this was happening at idle (about 700 rpm) while filling. So, am I ok here? It is for sure COLD and it held vacuum with both sides closed for a half hour, so there is no leak in the system.

From what you have described, the AC system is performing normally. It is a bit overcharged - should be 30 oz., but it probably won't hurt anything. At idle the engine rpm limits the volume of refrigerant that the compressor can provide to the condenser and evaporator. With the fan speed set on high, the air flow through the evaporator is high so the refrigerant flowing through the evaporator core can't keep up with the heat being exchanged; consequently, the low pressure side won't drop low enough to turn off the compressor. If you turned the fan speed to a low setting, the compressor would begin to cycle again.

If you hear a heavy clunk sound when you turn on the AC the first time for the day, that would be caused by refrigerant in the liquid state entering the compressor inlet . It is called slugging. An overcharge could cause that symptom.

- John