MasterBilt walk in cooler issue

[Eadam1985]

I was working on a masterbilt walk in cooler r-22 dual evaporator ive been there 2 times manager says it wasn't cooling when he gets in but everytime ive been there it was down to temp. I thought it might be the defrost set for too long it was originally set for 12am and 12pm 45mins in defrost so i set it for 25mins defrost then i got called back on sunday and temp was 57 degrees and not droppping my condenser was running i had a 10 suction and a 150 head i checked my pipe temp at oulet of both evaps it was 56 degrees so i thought maybe my liquidline solonoid might be having issues so i took the temp on the inlet and out let i was getting 92 degrees, and checked if my solonoid was gettig voltage and energizing it was so i added some refrigerant to see if pressures went up i added 5oz of refrig and my compressor made a noise like it had a high load and then my pressure went to normal had 45 suction and 180head and started cooling the box down i dont think it was low on charge does anyone have any ideas what could be going on? i have a feeling ill be getting that call back im an a/c guy and new to refrig and advice is greatly apperciated

[indy2000]

model and serial #?

[Eadam1985]

model mhhx030ccc serial 0j434834 it has can coil thermal corp evaps

[Eadam1985]

0s434834 sorry cant read my own handwritting

[hvac wiz 79]

Was it a cold morning when you went back?

Sent from my SCH-I800 using Tapatalk 2

[Eadam1985]

eh not really it was in the 70s its weird cause i was there 3 days prior and i was getting good pressure and it was around the same outside temp

[2sac]

Low on charge

[Capz]

Adding 5 oz to a system holding better than 5lbs? Are you sure there are no loose connections on the solenoid wiring? Or the dual pressure switch could be out of adjustment or faulty in some way? The Ranco should DE-enegize the NC solenoid thus pumping the compressor down to about 10psi, and this should de-enegize the compressor contactor. I'd check to see how low this compressor will pump down too.

[jackintheboxtec]

Low on charge

Does this unit have a sight glass?

[ryan1088]

Does this unit have a sight glass?

X3

[Dchappa21]

Yep add the winter charge to this thing...... It's starting to get cold at night and will need to flood the condenser to operate properly.. If it has a headmaster that is.

[indy2000]

Does this unit have a sight glass?

It should

c/p
Finish Charging Procedures
A. Preliminary
1. Be sure all service valves are “open”.
2. Loosen the compressor hold-down bolts and remove shipping clips to allow compressor to
float freely on the springs.
3. Check evaporator fan motors after start-up. Medium temperature, air defrost fans run
continuously. Low temperature fans and coolers provided with electric defrost will be
delayed by the fan control.
11
4. Start the system by “flipping on” the circuit breaker in the unit electric box.
5. Start charging per (B), (C), (D) or (E) on the following pages.
CAUTION: Never add liquid refrigerant to the suction side of the compressor.
6. Check operating pressures while charging and on initial pulldown to prevent damage if a
problem occurs. If system “floods” back to the compressor, adjust the thermostatic expansion
valve as required for proper operation. There should be at least +30°F superheat
entering the compressor.
7. Observe compressor amperage draw and compare to compressor nameplate to prevent
damage due to high amperage. The oil sight glass should be between 1/2 and 3/4 full
during normal operation.
B. Remote "M-Series" Condensing Units
1. For models without head pressure control valve: With the system operating, add
refrigerant until the sight glass indicates a full charge, then add one pound for each 2 rated
horsepower of the condensing unit when charging above +75°F. If ambient is below +75°F,
add 1/2 to the above. See A.6 above.

[2sac]

Adding 5 oz to a system holding better than 5lbs? Are you sure there are no loose connections on the solenoid wiring? Or the dual pressure switch could be out of adjustment or faulty in some way? The Ranco should DE-enegize the NC solenoid thus pumping the compressor down to about 10psi, and this should de-enegize the compressor contactor. I'd check to see how low this compressor will pump down too.

The 5oz he added was just enough to get the headmaster to kick in.