A/C freezing lines

Because I can't fit everything into a comment I will ask questions that might supply you with an answer.

What Refrigerant are you dealing with R22 , R410A ???

1: What is ambient temperature? 2: What is Indoor Temperature with in say 20 feet of your return air duct ? 3: What is the air temperature on the exit side of your evaporator ? This Should be about 20 degrees below Inlet Temperature measured in step 2. So if Indoor Temperature measure din step 2 is 75 degrees, the Temperature Measured 12 inches after the Evaporator should be 55 degrees.

So if your Indoor Fan is not moving enough air (your temperature drop will be greater > 20 degrees - or this could freeze up evaporator ) or is moving too much air (Your temperature drop will not be enough < 20 degrees).

Since you replaced your fan - CHECK the Wire Taps for the proper speed settings!

4: Your Suction PSI will vary some with Ambient Temperature ..a general rule of thumb 225 on the high side and near 70 on the low For R22!

If your low side is fine and your high side is low - your compressor valves are probably leaking.

You show both High side (<180 PSI) and suction side ( @55) both are too low (R22) This means With an Evaporator Freezing up - This is usually an indication that you need to ADD Refrigerant.

Yes your assumptions are correct and your answer is the same thing I thought. However, adding R-22 does not correct anything - suction rises to 70psi but head pressure does not rise in conjunction at all.

Just for kicks and grins, I disconnected the condenser fan motor and that got the head/suction pressure up and then dropped back down to 55/180. O/S temp 75-19F I/D fan motor 1075rpms and tapped for the high speed (cooling). Ducts are all blowing.

I did replace the metering piston, thinking it might be sticking. It was sticking/hard to get out of old coil. I did change I/S EVAP COIL and put new piston in, in-addition to chg I/D fan motor (Old coil was beat up pretty bad and was not allowing air thru). Before I found I/D fan issue no problems.

The way I saw it w/o seeing the duct work (next), the unit is either severely overcharged or the compressor's valves are an issue (providing no issues w/duct). I have never had this issue before, friends in the business are at a loss also.

Thanks for your input, I will be working on it. Tony