Frozen Lines

[myhvacx]

I need help, R22 18 Ton Rheem 2 stage 3 phase unit with a frozen low side problem...

One of the compressors is running at 15 Superheat and seems to have no problem at all..

The second compressor's low side keeps freezing up and therefore affects compressor 1.

Here are some stats taken earlier today...
Dry bulb 92F

27.3 Degrees on Low Side / 51 Psi
154 Degrees on High Side / 340 Psi
Superheat approx 5

The pressure was lower on the high side when I first got there and when I added freon it got up to 350, the low side temperature does not seem to improve at all with the added refrigerant..

I have checked the evaporator, clean, no restriction on the return...

Any Ideas?

[deon]

sounds like txv problem or restricted drier

[B1978]

recover and change the powerhead of the txv, also replace the drier. If thats a heat pump, verify you dont have a restriction at a check valve.

[myhvacx]

In my original post I did not mention (sry) that I left the unit running but there was no frost at the point that I left, also the inside had hit 75degrees, which it had not before...

This is a bar & I went back out there yesterday because manager said, it was 80 degrees around 6pm, I asked him to shut off the cooling mode and keep the fan running while I got there, which he did.. or did he???

When I got there though (45min) there was no ice, not even water or moist near or on any of the lines and the evap was pretty dry as well., This is a rooftop package unit I am talking about, it was just funny that with approx 88degrees ambient temperature I had not found "any" evidence of frozen lines, gave me the impression the unit had not been on for at least a few hours, which made sense because this place does not open during the day really.

Well anyway, make a long story short, this time I just went there to turn the damn thermostat on to 76degrees and stayed there for at least an hour to see about that freezing up issue and nada, pressures and temperatures seemed just fine... During this time, I asked the person in charge not to set the temperature too low. I think all in all what was affecting this system was just poor thermostat skills..

This morning I found out that system worked like a charm last night so.. I thought I come back and share this with you guys, thanks for your responses..

[socotech]

51 low/ 340 high = unit not cooling properly

[SubyDude]

sounds like txv problem or restricted drier

Copy that!

[pecker head]

Definetly restricted somewhere.. I would recover that charge and blow some nitrogen through there and see what happens...