System was thawed out upon arrival, tenant said it would work for a little then air would flow would drop dramatically, what was happening was coil was freezing over inside and blocking air flow, upon arrival checked pressures low side at 32 psi and high side at 132 SH 70 SC -2.3. Filter was changed last visit, all supply vents open, recharged system with 2 pounds 8.50 ounces, rechecked pressures 70/180 SH15.4, SC 11.8. Delta t at unit was 20 degrees, and inside home delta t at 17. Spoke with landlord who gave us the ok to do the repairs office has CC info for billing, also spoke to him about unit being obsolete so no guarantee on how long charge will last. Also checked joints what I could see with electronic leak detector which I did not find any leaks.