I've been dealing with A/C issues at work for the past few years...
The service guys tell us the most important thing in A/C health is keeping the fins of the compressor CLEAN...run/spray water in a back-flushing mode (against the air-flow) to remove all the air-borne fluff, grass and pollen that's clogging the fins/boas (that fluffy, feather-boa-like stuff), being VERY CAREFUL not to fold over the fins (There are commercial fin-combs you can buy to straighten out folded-over fins...works great on car radiators, too!!)
The heat's not being removed, the head- and tail-pressures will increase to the point that if there's no cut-off switch for too much high-pressure, the compressor will overheat and (hopefully) a shut-off thermal switch will kick in...depending on the cheapness of the compressor head part of the system, you may not want to find out that little secret 'til you talk to your serviceman on that.
If your compressor has never been cleaned, there are commercial grade fin cleaners out there...FOLLOW THE LABLE DIRECTS
CAREFULLY! The cleaners are caustic, but they'll pull a ton of stuff out of your fins even AFTER you thought it was clean. After doing the cleaning with the cleaner about three or four times (not all at once, over a period of months), you'll be able to just rinse the fins with a regular garden hose and spray tip...just reduce the useage of the cleaner to every other two or three rinsings...
Cleaning the fins takes care of about 85% of the problems...the rest is usually a small leak in a connection someplace or a hole that developed along a part of the line near the compressor that wasn't properly routed and may be rubbing on the frame or metal-work of the housing...just look around the tubing coming and going from the unit for little signs of "something is just not right" and you'll probably find something, or not. Don't go blame the installer for that type of problem...I've had lawn-mowing persons "bump" the condensor unit, or its frame, and that type of movement will be enough to cause one of the lines to re-align itself against something metal...if that's the case and see something like that, let a serviceman come in with a "sniffer" or leak-find fluid and let them handle it from there.
Now, if you're undercharged, you'll find that the coil in the air handler will probably "ice-over" - call the serviceman to check that out...but one thing you can do to save the call on that, first!
Open ALL REGISTER VENTS to be sure there's enough air-flow over the coil to keep the coil from freezing solid...too low of air flow will appear as an "undercharged system" when in reality, you have someone in the house that's too hot and has shut all the other vents down to get more cold in their area. (I learned that the hard way! ($203.00 the hard way!
)) So be careful closing down vents to transfer cold to other areas that aren't cool enough...in those cases, it's probably better to have a "booster-fan" installed in that branch of the ducting system to assist in getting a better balance of cooling throught the whole home.
Good luck fixing this...just remember...a little effort on your part keeps your bucks in your pants...
