why did this unit freeze up
Appreciate some help here , first here is the info, I've been here long enough to know you guys want a lot of data:15 year old , r-22 ,1 1/2 ton rheem split,orfice, low side pressure 68, SH 5.6, T1 46, high side pressure 284, SC 38, T2 88, ambient 95, current draw in range 8.4 amps. Inside at return - dry bulb 77 wet 63, supply - dry 67 wet 53, small 600 sq ft apartment, unit in central hall closet with short supply in furred down ceiling ( 12 unit complex I own , so I have other units to compare data with) PROBLEM - mowing yard and find this unit with suction line ICED up outside -- Been thinking head was a little high in earlier checks ( taken 4 previous readings in 2 prior months, all readings near above), so I cleaned condenser coil --(after cleaning and unit off awhile, I checked line temp 81 against line pressure 147 which made me feel no non condensables in system) when running ,no drop across filter/dryer either. After cleaning, low side barely changed, high side dropped 10 PSI, all else almost same (SC, SH, T1 +T2) - SH says low charge, pressures seem fine- SC says...I don't know :readings taken at valves with my testo 550 . Unit was unoccupied for a week and stat set around 80 when freeze occurred. Any constructive ideas appreciated.