Pegasus Horizontal Freezers - Irregular Freeze-Ups

Overview

It has been reported that some Pegasus horizontal cabinets have irregular evaporator coil freeze-ups. If a
Pegasus horizontal cabinet is prone to irregular freeze-ups, the following checks should be made to
determine the possible cause. Refer to the procedures throughout this bulletin to complete the checks.

1.  Evaporator defrost probe location (page 1)
2.  Parameter set (page 2)
3.  Refrigeration unit seal (page 2)
4.  Cabinet door seal (page 3)
5.  Evaporator fan operation (page 3)
6.  Refrigerant charge (page 3)
7. Manual defrost (page 3)

    Cabinets Affected

    Cabinets affected include the Pegasus horizontal cabinets noted in the table below:

Procedures

Follow the procedures below to determine the possible cause of irregular freeze-ups.

1. Evaporator defrost probe location

Check that the defrost probe is correctly installed into the evaporator coil. The probe should be fed
approximately 20mm into the evaporator coil, 6 fins (40mm) in from the side of the coil and inbetween the first (bottom) and second pipes (see diagram below). It is critical that the probe is pointed downwards.

2. Parameter set

Check that the electronic controller is using the correct parameter program (applies to SKOPE CAREL ir33
electronic controller only). The electronic controller has a SKOPE electronic controller program configuration
label attached to it showing the controller program. Once the program set is identified, ensure that the
program is using the correct set (bn number) by performing a controller reset and selecting the correct bn set. Pegasus horizontal freezers with SKOPE Carel ir33 controllers use program 475 set bn1 (integral) or BN2
(remote). The controller should never be left in set bn0 as this may cause failure.

3. Refrigeration unit seal

Check the integrity of the seals around the refrigeration unit and ensure that the unit is correctly sealed to the cabinet. Inseal must be in place right around the perimeter of the refrigeration evaporator compartment as shown below (shaded). The refrigeraion unit must be firmly sealed against the side of the cabinet.

Also check that the unit is sealed correctly from the inside of the cabinet by pushing on the centre of the
sheetmetal part shown below (shaded). This part should not depress. If it does, add some inseal or foam tape to complete the seal.

4. Cabinet door seal

Check that all of the doors close correctly and that no obstructions are preventing the doors from closing. Also check that there are no leaks from the door seals. This can be checked by placing a torch (turned on) inside the cabinet, shutting the doors and checking for any light leakage.

5. Evaporator fan operation

Check that the evaporator fan is operating correctly. On a freezer system the evaporator fan motor is
controlled by temperature and will not turn on until the evaporator coil temperature drops below -8°C. The coil temperature can be verified by checking the d/1 parameter within the electronic controller. Pizza and Prep cabinets run the evaporator fan motor when the evaporator coil temperature drops below +20°C.

6. Refrigerant charge

The refrigerant sight glass can indicate the presence of moisture within the system. If the sight glass is not
indicating dry the system has a leak. If the sightglass is not clear while the compressor is running there
maybe a refrigerant shortage and system leak.

7. Manual defrost

Perform a manual defrost by pressing and holding (5 seconds) the button on the electronic controller
faceplate. A manual defrost will start if the evaporator coil temperature is below the defrost termination
temperature. If the controller temperature reading is above 0°C a manual defrost cannot be initiated.

Manual defrost is useful for checking two things:

1. That all defrost elements operate correctly and fully clear ice from the evaporator coil
2. That the electronic controller defrost relay is operating correctly.