Harbor Diesel

Too Hot!! Living in south Fla. The A/C Just never seems cold enough! My 2001 2500 Has some sort of leak that I cannot seem to find. I added refrigerant about a month ago and it has slowed the leak almost completely. I am not too pleased with any A/C mechanics in this area. (havent found the right one yet), so I am trying to correct this problem for now till the summer is over. Problem is I cannot find the proper pressures for my system. I have 25 psi compressor running and 80 psi compressor off. Air is cool but not like it is just after charging. The gauge attached to the can says a little low at 25, Should be about 30-35. Should it be 85 psi when the compressor cycles off ? (Red Area). Add more refrigerant or is it time to see the A/C doctor? Any help is greatly appreciated, Its too Hot, Why Did I move here any way? Always did like the snow!! Thanks!

Busboy

Recharging this truck is tricky, you should really have gauges hooked up to the high pressure side as well as the low side. Without knowing the high pressure you don't know if there is something else wrong. Before you start make sure that the engine cooling fan is not just free wheeling but is drawing air through the condenser in front of the rad and make sure the condenser is clean, any bug screen should not be up against it. Recharge the AC with the controls in MAX AC and FAN on FULL. If you only have 25 psi suction my best guess is it's low. I forget what rpm the book calls for but around 1800 rpm would be fine to add freon. My trucks a 2001 and I recently had to replace the evaporative core due leaking. It rotted out on the bottom. If it is leaking one from a gas truck is identical so you could get one from a wrecker.

If it continues to loose charge then have it leak checked, it should only take about 10 mins.

Busboy

The 85 psi you're reading is the pressure in the system and means nothing it will change with the temperature. The same can be said of the high pressure (discharge) reading, it too will change with the temp but also with the amount of air passing through the condenser (rad). The suction pressure should be around 32 psi with the comp running. Aim for a duct temp on the drivers side of about 45 deg F I don't think you could do much better in the hot climate you're in and using 134a.

Harbor Diesel

Thanks Busboy, I will add a little more. I had no idea that the rpms needed to be up to 1800. I always added refrigerant at idle. The other thing that puzzles me is the oil and gas ratio. Is there any way for me to know If I have added too much oil and there is not enough gas refrigerant or is that something best left for the A/C tech to figure out. I was planning to remove the radiator to clean out the accumulated oil and debris as I have not relocated the blowby bottle. while i'm there I will clean the A/C coils too. Thanks again!

Stamey

I have never added refrigerant above an idle, unless I am trying to suck down the last part of a can.
The igh pressure you see on the low side when the AC is not running is natural, in that the high and low sides equalize when the compressor is not ruinning. As Busboy said, that pressure will vary, depending on how much refrigerent is in the system and the abient temperature of the day.
I also agree with busboy that you need to have guages on the high side as well as the low side. Experienced people call those little cans with the guages on them "suicide kits" for a reason.

Chris

Busboy

Sorry, the temps and press I gave were off the top of my head and were for 70 deg at around 1800 rpm. The book says for 80 degF duct temp should be 55-60degF and suction press 40-50 psi, for 90 degF 60-70 degF and 50-60 psi. but asks for only 1000 rpm. I find the AC performs better with a little more RPM like I said around 1800 is where I check it. It also says that if the duct temps are ok and the suction pressures are lower than the book then the AC is working normal. You CAN add freon at idle but it takes longer and as you are topping up without the proper gauges you need to know where the system is at temp wise, thats why I suggested 1800rpm.

Unless you have lost oil there is no need to add any, oil can be added with an "oil injector" without draining the system. If the system sat empty for any length of time you will have to have the system evacuated (vacuumed out) this "boils" any water out of the system. I would also change the dryer if this was the case.