AboutJ Cook Expertise With 25+ years experience, I am familiar with residential, commercial, and industrial HVAC equipment including but not limited to boilers, chillers, reciprocating and screw compressors. I am trained in all manners of control wiring.
Experience I currently have three HVAC licenses and Refrigeration license by the State of North Carolina. I have been in this field for over twenty years. I have been a service technician for a contractor and also worked at a state college in the repair and maintenance of steam lines and equipment. I am currently the Building Maintenance Superintendent for a municipality.
Question During a recent checkup My mom's Lennox 10 SEER 2 ton with Armstrong indoor coil has developed a leak after 13 years of perfect service. I confirmed very low refigerant with 60 psi high side and 0 psi low side. I've charged to 200 psi nitrogen pulled back the insulation and check every joint with bubbling solution. I've been unable to check the entire indoor coil and get inside the outdoor unit to check the compressor. I left the gauges on for several days and have no loss of psi (still reading 200). This is looking like a very difficult leak to find. My next thought is to evacuate, fill with small amount of r-22 and check with a leak detector, but given I've lost no nitrogen so far I'm not so sure this will pan out as I am not that skilled at finding leaks.
Any other thoughts, ideas, etc. would be greatly appreciated.
Answer An R 22 unit is pressure tested at the factory to at least 350 psi. I do not go that high, but you can easily go 300 psi and continue searching for a leak. I usually put liquid soap such as Joy dish detergent in a spray bottle and saturate every fitting, the brazed joints as well as every nut fitting. You are also describing a perfect scenario to have leaking schrader valves where the gauges connect. With the gauges connected it will not leak. After checking the fittings and coil with soap, remove the gauges with the nitrogen still in it and soap the actual valves to see if they leak. Thanks J
