high sub cool,high super-heat with r410A

[moideen]

Dears,
Today I checked RHEEM 3.5 ton SAGL split unit. The complaint was ice forming frequently on cooling coil. As per my primary checking suction superheat is high 33K and sub cooling is 14k. Liquid line filter is ok and the metering device is TXV factory adjusted. The refrigerant 410a, the contractor used brand FREO + unknown brand refrigerant. I think china. Before doing any action, I felt may be the refrigerant is mixing and contaminated. Now the evacuation is in progress……
after charging the with good refrigerant ,let us see the readings.Am I correct?:cool:

[frank]

Hi Moideen
Changing the refrigerant for fresh and to the correct charge is a good first step as this will allow you to disregard these as a possible problem with further trouble shooting on the system

[NEugeny]

Massflow of refrigerant is too low. Maybe expansion valve is almost closed. Try to heat thermo bulb.

[RANGER1]

Also no suction or discharge pressure readings to relate to anything.
You may have them but we do not.
IF you new nothing of previous work, would you have done the same thing!

[moideen]

already evacuation started, i will update all new readings....

[monkey spanners]

There have been problems with txv's failing due to a chemical reaction of some rust proofing chemical copeland started using and the systems refrigerant and oil making a sticky substance which gums up the orifice. It gives symptoms of a failed txv.

http://www.danfoss.com/North_America/BusinessAreas/Refrigeration+and+Air+Conditioning/News/Customer-and-Field-Bulletin-Residential-Air-Conditioning-TXV-Failures/FF55CA16-C2B7-4DD2-A2CA-E660408F9223.html