a/c not cooling on idle

When I first got in my truck, the AC wouldn't cool below 70. I straightened out some fins, then got down to 60. It would warm up at idle, so I'd have to kick the rpms up to 1000 and leave the fan on.

The company would save $$$ by replacing the condenser. Especially since they just replaced the oriface tube, bunk evaporate valve and the drier

 

I your case, to confirm the condenser, once the a/c has stopped working and low side pressures are too high try pouring water all over the condenser with a garden hose. If it starts to cool again you have found your problem. Sometimes the cooling fins become detached from the tubes on the condenser and the heat exchange isn't as good unless the truck is at highway speeds.

 

Sodapop, ur not going through the change are u and having HOT flashes?

 

If you have 75 lbs at Idle on the low side, them you definitely have a problem, the expansion valves are either corroded out or you are way over filled. If the shop does not check the oil level go to a different shop. If the shop does not evacuate the system for at least 20 minutes go to a different shop if they do not wait to see if the system holds a vacuum go to a different shop.
You can check the cab air filter, and the heater flow control valve if they are not right get them fixed.
It really helps if you tell us what truck you have whether you have a sleeper, every bit of information helps.

 

To wash out the radiator, AC condenser, transmission cooler cores, can all be washed with a pressure washer, with heavy soap, and direct the flow directly at the core from about two feet. Do not do it at an angle or it will bend the fins. It will not hurt the cores or you would not drive in the rain. First do a systematic pattern, 2 inch rows, from top to bottom, then run the unit fan on at 1200RPM, and do it again. You can see the air flow from the spray, and tell were the rad is dirty and flow is blocked.
If you have one of those real pretty plastic bug screens put it on and watch the spray pattern with and without it then throw it away, and spend the money on a metal screen. If the AC condenser is damaged severely get a new one, they are cheaper than paying for continual repairs and will pay for them-self in saved fuel, not having to run the system longer than needed.
Just a thought!

 

I ran to a similar problem and it was a leaky heater valve. So now I shut off the heater valves from the engine block, problem solve.