Six door reach in case won't pull down

[joe magee]

I have a brand new 12' six door reach in self contain case. On start up without product the case pulled down to temp. After two weeks contractor found compressor grounded. he installed a new compressor and claimed the suction would not come down or come down very slow. Two weeks later this compressor grounded. A new compressor was installed. It's a 404A case with a 5100 btu condenser and two Danfoss TU#2 valves. The engineering numbers on the case are consistant with the condenser, fan speed and TXV size, There are two coils in the case. The amp draw was RLA while I was onsite the suction was cosistant with the 63 degree case temp. the contractor had weighed in the factory charge and subcooling was 3-5 degrees with a clear sight glass. The case is filled with bottled wine so there is a load on it. The case only drops 1 degree in an hour. discharge is pressure is consistant with ambient, Not relly sure where to go. I have seen a bad external line on an expansion valve causing the refrigerant to blow through and back to compressor though my superheat is high. I notice not alot of action going at distributor. I'm thinking with that high heat load the refrigerant is just flashing off. Any ideas ?

[chillerman2006]

Sounds like expansion valve blocked or incorrectly set

Pump down, check/clean valve/gauze/filter, purge (haha only joking), change drier, vac out & set superheat to 5-7*c

Quick smoke & she'll be down to temp

R's chillerman

[Coorsman777]

I agree. Sounds like the expansion valve is not working properly. Either a problem with the valve itself or the liquid feeding it.

[joe magee]

There is two valves in the case. My argument with a plugged valve would be low suction where now the suction is consistent with case temp. I agree that possibly a bad valve/ext EQ could still be an issue.

[al]

log your temperatures, liquid into valve, temp at distributor, temp at first pass on evaporator, this will quickly highlight if one valve is defective, have you warmed the expansion valve bulbs to see are they closing down while running, if so moisture would be suspected, alternatively slap in a no6 orifice temporarily on both and check system reaction!

al

[Magoo]

Sounds like system overload with product loaded, and compressor at RLA, possibly install a crankcase pressure reg valve in common suction and allow compressor to handle loads, alternatively MOP expansion valves. Under high load the liquid line would be undersized for duty, in turn compounding problem of flashing liquid to TEV's, high suction pressure , high suction super heat and high current draw at compressor. Compressor failure.

[joe magee]

Went back to store yesterday.Opened each valve a couple of turns. Once case came down to 38 (24hrs) Super heat 8 degrees at coil 47 degree return temp and 15 degrees super heat at compressor. Raised case temp to 40 It's only wine with a 3 dead band. From what I can see is the condensing unit struugles to pull case temp down.