Dear Angie: Is it possible for an HVAC technician to overfill an air-conditioning system with refrigerant? (My system uses R-22.) For example, if the system needs 2 pounds, is it possible for the technician to force in, say, 3 or 4 pounds? If so, can this damage the A/C system or cause it to malfunction and stop cooling?
My technician said my unit, which wasn't cooling well, was low and added 6 pounds at $100 a pound. I later learned that it holds only 6 pounds of refrigerant. Just two days later, it stopped cooling well again. — A.D., Bethesda, Md.
Dear A.D.: It is possible to overfill an air conditioner with refrigerant, and unfortunately, several problems can occur that could permanently damage the unit.
To start, an overcharged air conditioning system will decrease both its efficiency and its capacity to cool. One highly rated heating and cooling technician on Angie's List said that it would be the equivalent of a three-ton system operating at the capacity of a two-ton system. When cooling demand is at its highest, the system probably won't be able to meet it. Depending on how overcharged the system is, it's possible that it could stop cooling altogether.
Another side effect is the potential to increase the temperature of the indoor coil, reducing the dehumidification of the indoor air, which is an important benefit of conditioned air. The air in your home is likely to feel sticky or muggy as a result.
The greatest potential damage, though, is to the compressor. Overcharging the unit can cause permanent failure of the compressor, which is the pump for the refrigerant. Replacing the compressor can cost more than replacing the entire outdoor unit.
Some air conditioner systems have an automatic shut-off if the internal circuitry determines that the system has been overcharged, which could help minimize the damage. When this happens, though, the system will power down. It must be reset and the overcharged refrigerant removed before it will turn on again. So expect to require the services of a technician if your system does automatically shut off.
The larger question here is why your technician added so much refrigerant to begin with. First off, if the technician suspected a leak, he or she should have performed a leak test before adding any R-22. As you probably know, the cost of R-22 refrigerant is rising quickly, because of a federally mandated phase-out because of its ozone-depleting properties. Homeowners are paying three and four times the cost of R-22 than they were just a few years ago. No longer is it financially feasible, or environmentally responsible, to simply ignore a leaking unit and recharge it with more refrigerant.
It's possible that you simply had an under- or untrained technician who made a mistake, or it could be that the technician sold you more refrigerant than you needed. I recommend that you contact the owner of the company you worked with and discuss your concerns. If the company has a good history and the technician simply made an honest mistake, they should be more than willing to fix the problem at no cost to you. If you're uncomfortable calling that company back out, you could call a few other local HVAC technicians with good reputations and ask them to independently evaluate whether your system was overcharged.
I hope it doesn't come to this, but be sure to keep all of your correspondence and documentation relating to this job in case you need legal recourse.