VF1000 and VF1300 - Rear Port Ice-Over

Overview

There have been rare occurrences of rear port ice-over on VF Freezers. When rear port ice-over occurs, ice has formed and completely covered the rear port hole, which stops cooled air entering the cabinet interior. This may result in a situation of melting/defrosting product while the electronic controller displays cold temperatures.

To overcome this, SKOPE has created a rear port probe kit. When fitted, the rear port probe kit provides enhanced defrost control, eliminating rear port ice-over.

A number of different causes may result in rear port ice-over. If a VF Freezer is found to have rear port iceover, an investigation should be carried out to determine the cause (see below). If rear port ice-over continues after completing the investigation, order the rear port probe kit from SKOPE (see further below) and fit to the freezer unit.

The rear port hole is located on the ceiling of the cabinet interior, behind the back duct, and can be viewed by removing the evaporator box lid. Air is forced from the freezer unit down into the cabinet through the rear port hole.

Investigation

If a VF Freezer is found to have rear port ice-over, use a hot air gun to warm the area and clear all ice, and perform the following checks to determine the possible cause:

1. Check the door gasket for leaks. If necessary, refit or replace the door gasket.

2. Check the integrity of the seals around the refrigeration unit. If necessary, replace the inseal tape to ensure a complete seal.

3. Check for correct evaporator fan operation.

4. Check for correct defrost operation. Perform a manual defrost and ensure the defrost elements are operating correctly.

5. Check the initial temperature of loaded product with the customer. Avoid loading of product at nonstorage temperatures. Product temperature must be less than -18°C when loading into the freezer.

6. Change electronic controller dripping time parameter dd from 10 to 3 to minimise condensation (programming instructions available in the product service manual).

If the rear port ice-over continues to occur, order the rear port probe kit from SKOPE and fit to the freezer unit.

Rear Port Probe Kit

Rear port probe installation involves replacing the existing ambient probe with the rear port probe, and making some parameter program changes. Refer to the instruction sheet (PRN11111) included with the Rear Port Probe kit for full installation instructions.

When fitted and programmed, the rear port probe operates in conjunction with the existing evaporator (defrost) probe to control defrost cycles and evaporator fan start conditions.

Defrost cycles will not terminate until the rear port probe reading is >4°C and the evaporator probe reading is >4.5°C (within an extended maximum defrost cycle duration of 45 minutes).

The evaporator fans will not start until the rear port probe and evaporator probe readings are <15°C.