I just had a technician out to do a tune-up on my heat and air conditioning. He tested the amperage on my compressor, fan motor and blower motor. They were all below the rated amperage. Is that a good thing or bad? Also, does anyone know what a reasonable cost to recharge freon in a 4 ton unit would be?

It depends upon the

Temperature out of the condenser
Temperature of the air going into the condenser
Temperature of the air into the evaporator
Temperature of the air leaving the evaporator
Suction pressure
Liquid line pressure
Suction line temperature
Liquid line temperature
Calculated superheat/subcooling

If you have all the above information I can get you close.

There is no reasonable cost. All areas of the country charge different amount for labor and materials and how much refrigerant is used in the process.


Low amp draw usually means the machine is not working very hard BUT it could be other items also

Hvac, how about Altitude? Just curious.

Here is a older Unico spec sheet for air flow at altitude. Something tells me 6% loss difference at 5000 for most refrigerants.

http://unicosystem.com/Portals/0/Pdf_Files/TECHNOTE103(2005-03).pdf

Depending upon circumstances flash gas can be a problem at altitude. The flash gas causes a decrease of COP (coefficient of performance).

Cap tube systems can be stinkers at altitude.
If checking the refrigerant charge then consult a temperature pressure chart corrected for the altitude in which you are servicing the capillary tube system.

Thanks, Take Care

You probably have anywhere from 5-7 pounds of Freon in the system. If it was low on charge, expect about 2-3 pounds max to be added (unless you have a major leak) I believe R-22 costs around $6-7 per pound and most contractors are charging double per pound and sometimes triple (that would be on the higher side) The time should take no longer than 1-2 hours, so figure the service charge and hourly rate.