walk in cooler questions

[ekcs]

M#PHHZ0070B 

Hey guys, i went to a walk in cooler where the complaint was the unit was to warm.

I arrived at the unit to find the box temp to be 46f-49f, 
cold control is calling for 37/39ish (hard to tell exactly)
the temp where the condenser is (above the unit in the ceiling) 90f
Freon: R404a
Suc pressure: 51-56
Dis pressure: 260-274
SH: 28-30
SC: 9-12 
temp across high side filter dryer 2 degree
compressor amp draw is 7.6
Evap temp was 21f according to my IR temp gun
condenser fan 2 amps
condenser coils are nice and clean.


Questions i have currently have are:

Where exactly should i be placing my probes? my SH probe was on the suction line 6 inchs away from the king valve. my SC probe was placed on the liquid line coming out of the compressor.

on the low side king valve i noticed two valves i could connect my gauges to. i took the cap off one of them noticed pressure coming out so i closed it back up. (keep in mind the king valve was still closed when the pressure is coming out) then i opened the send cap still on the same low side valve. and no pressure was coming out. Why is pressure coming out of one side when the valve is closed?

would i be wrong to say that the SH is way too high?

is it wrong to try and bring the superheat down by adding a small amount of 404?

What else should i be checking when i first approach units like this?

Any replay is more then welcome.

Thanks to all in advance.

[jumptrout]

Are evaporator fans running unobstructed?

Is this unit cycle defrost or a defrost heater?

Is suction line well insulated?

[alamo1718]

SH temp probe goes at the exit of the evaporator, or as close as you can get. Same concept  with the SC probe, as close as you can to the exit of the condenser. Try these placements and see what you get. Also, what's the metering device? If it's a TXV, the sub cooling will be the important number. The TXV maintains superheat, if there's enough refrigerant  available. Check the sight glass. It's in the liquid line, after the condenser and before the metering device. If it has bubbles showing, it might be low or have a liquid line restriction. Also, there is not a liquid line off a compressor. It can only have a suction and discharge, both are a vapor. It condenses into a liquid in the condenser. 

Find the service label. It will list FLA for the compressor. I looked up the generic info online and it seems to be running at expected AMPS. It may also tell you the sub cooling goal  for this system. 

 

[ahh-cool]

Put a box fan blowing on the condenser