20 • Refrigeration
REFRIgERATION
Mechanical Components
EVAPORATOR COIL
The evaporator coil, located at the rear bottom of the case, is factory assembled with distributor, expansion valve, and other refrigeration
components. To inspect the coil, remove the center or left of center coil cover. A small inspection window is located at the rear of the case. To
inspect the entire coil, remove the remaining coil covers and raise the evaporator cover.
EVAPORATOR FANS
Air is circulated throughout the case by fans. Fan motors must be operating at all times except during defrost. Fan motors should be replaced
with motors having the same characteristics including type, size, lubricant temperature range, wattage, and RPM. Fan blades should be
replaced with OEM parts or have the same fan pitch as the OEM fan blade.
!
CAUTION!
DISCOnnECT POWER TO THE CASE BEFORE SERVICInG ELECTRICAL COMPOnEnTS TO AVOID PERSOnAL
InJuRY AnD DAMAGE TO THE unIT.
1. Disconnect power to the fan.
2. Remove the fan blade nut and fan blade.
3. Remove the two mounting bolts and remove the fan assembly from the fan housing.
4. Remove the three fan motor mounting screws from the back of the fan motor.
5. Replace the fan, and reverse steps 1-3 to install the cover and restore case power.
EXPANSION VALVE
Unless otherwise specified, a superheat-adjustable, externally equalized thermostatic expansion valve (TXV) with a removable strainer and
pressure limiting charge is mounted to the evaporator coil. The TXV is not preset. Adjust the superheat setting for maximum coil effectiveness.
Typical superheat settings are between 6°F and 10°F. Contact Zero Zone for superheat setting if using high-glide refrigerants. Cases connected
to a condensing unit should use the higher superheat setting to minimize the chance of liquid flood back.
To adjust the TXV, remove the right end coil cover. On Sporlan TXVs, remove the cap on the bottom of the TXV. On Danfoss TXVs, remove the
nut on the side of the TXV. When looking at the valve stem end, turn the valve stem counterclockwise to decrease superheat. Turn the valve
stem clockwise to increase superheat. Measure the suction line temperature at the TXV sensing bulb and compare it to the suction temperature
corresponding to the saturated pressure. Make sure that line pressure drop is taken into account.
Turn the valve stem only 1/4 turn at a time and allow sufficient time (20 to 30 minutes) for the TXV to settle before making further adjustments.
Replace the valve stem cap after the superheat has been adjusted.
Be certain the valve stem cap is wiped dry first.
Refrigerant Piping
Unless otherwise specified, the liquid and suction connections terminate inside the case under the coil cover. Refrigerant piping may enter the
case through the left rear back panel or the left rear top panel of the case. Other exit options are available. The copper pipe should not touch or
rub on the edges of the sheet metal.
Correct refrigeration line sizing and industry standard installation practices are essential for proper system operation. Zero Zone offers many
refrigerant choices. We recommend using the Sporlan Virtual Engineer Toolbox to calculate sizing for liquid, suction, and discharge lines:
https://solutions.parker.com/sporlanvirtualengineer
. Go to the link, select the line type, and then enter the information required to calculate the
recommended line size. Toggle between metric or imperial units as needed.
REFRIgERATION
