Returned to a commercial customer in Chico CA for a leak search and repair on a Lennox air conditioner. Found the bottom of the evaporator coil frozen. After thawing out the coil and performing the leak search, the technician was able to locate the leak in the u-bend of the evaporator coil. He repaired the leak and replaced the filter drier. Vacuumed and nitrogen tested to confirm no further leaks. Recharged with R22 refrigerant, system now cooling with a 23 degree temperature split. Job complete.
