When your A/C refrigerant level is undercharged, your unit will work longer and cause increased electric bill. Longer hours on the machine will cause a short equipment life span.
Remember! Any refrigeration system is a sealed system and should not have leaks. When a refrigerant leak this will cause not only ozone depletion, especially R22, but also your system will lose part of the compressor oil too. If you just top off the Freon your compressor eventually will not have enough lubrication.
When your system is undercharged, the evaporator coil in the inside unit will not be as cold as it supposed to be. The moisture in the house will not be able to condensate when it pass on the cold coil and will return into back to the living space. Even when the temperature on the thermostat is achieved, the moisture content is going to be high causing not comfortable environment.
To prevent the above problems, it is recommended that the system is inspected for leaks, and if there is, they should be fixed. If your technician add only refrigerant without even looking for the leak it is good idea to look for a different technician.
There are several symptoms of a system undercharged:
-Low on refrigerant.
-Bad TXV valve. The valve is stuck open or closed and it is not readjusting by the demand.
-Restricted airflow. Dirty air filter, collapsed duct, fan not working.