I have a 2 ton Luxaire central air cond. I installed it myself. The line set was 25 feet long, which is 10 feet longer than the pre-charge was for. I assumed that I would have to add freon-R22. Now, after my a/c runs for a couple of hours the comp. gets hot and won't come back on until it cools. I came to this conclusion because the cond. Fan was running and I had 240 volts to the comp, but it would not run until it cooled. I am hoping that an over or under charge would cause this. What should I do. I have the tools that I need, I just don't know what to do. Also my blower motor speed on the furnace can be changed to 3 different speeds. Is that a factor in this? Right now the low side is 80lbs of pressure and the high side is at 275lbs of presssure and at low blower speed it will sweat back to the comp

Thank You!
Jamespmiller

This time of year the suction line is always going to have moisture.
Also why do youy have blower on low? I would at least have it on medium. Others would say high for ac mode.
Did you add charge for the extra length? If so did you read the instal manuel for the proper amount of charge?

Depending upon the outside temp you could have a gross overcharge.

Sweat back to the compressor means NOTHING. That is like saying the suction line is beer can cold which also means NOTHING.

I hope you pulled a vacuum properly on the system before you charged it. If you did what was the micron rate when done? See below

Vacuum: How it relates to the air conditioning service - SPX Robinair

All systems being field built have moisture and non condensibles these must be removed prior to charging the system so you might have moisture/non condensibles along with the refrigerant in your system causing problems.

If you just brazed the lines then opened the condensing unit valves then you will have a problem if a good vacuum was not pulled.

At any rate the compressor is probably going off on the internal electrical overload and that is probably because the suction line is not going back to the compressor cold enough to keep the compressor windings happy. Keep doing that and the compressor windings will probably burn out then you will have a bigger problem replacing the compressor.

I highly recommend that you contact a qualified service person to do a ON SITE survey of your system and take corrective action before you turn this into a major problem.

There are many other possibilitys like the wrong piston flow rater/improperly installed expansion valve etc but to get to the true problem you have to be on site to see all the parameters and that cannot be done from here. Good luck.

On last item depending upon your systems refrigerant flow device you need to set the operating pressures by superheat or subcooling. The amount of refrigerant that is in the system from the factory means NOTHING and adding more refrigerant to the system by so many ounces per foot of additional line means NOTHING. Superheat or subcooling is the ONLY way to properly charge a system. Many manufactures will say you can also charge by refrigerant weight/pounds/ounces but that will only get you close not perfect.

:)