JOHN DEERE 6920 AIRCON SUCTION HOSE FREEZING

[newtonbury]

Hi All !I've got a problem with friends JD 6920 aircon .It has a new compressor ,dryer & expansion valve, it's been thoroughly flushed using a solvent flushing fluid,has no obvious blockages - all screens are clear but within a minute or less after starting it will freeze the suction hose.
Initial running pressures are fine at 2bar low - 10bar high but once it freezes it drops to <1bar low 6bar high and thaws intermittently then runs for short time until it freezes again.Should I be looking to change the thermostat control or the low/high pressure sensor/switch on the high pressure line before the evaporator ? Any suggestions would welcome !

[PBettis]

Are you moving enough air across the evaporator? No rat nest or debris/trash/foam filter blocking airflow? Both pressures (high/low) drop so it's not an internal restriction. If it were an expansion valve sticking or metering device blockage, the low side pressure would drop and high side would rise (climb). Frost is always visible after a pressure drop too great or restriction. I don't do automotive refrigeration but I've done residential my whole life and have a non-restricted state license. There are similarities....enough to get me in trouble..haha!

[jenkinsph]

I agree with PBettis to check the evaporator coil, all it takes is a poor fit on the air filtration system in a dusty field to block it up. If the coil and gas inside doesn't have enough air flow across it the return line will freeze quickly. In most residential systems I expect to see the return side of the evaporator to run about 40 to 45 degrees.