Why IQF Coil Not Clearing of Frost During Defrost Cycle?

SYMPTOM

IQF Coil not clearing of frost during defrost cycle

POSSIBLE CAUSE

1. Insufficient number of defrost cycles.

2. Insufficient time for each defrost cycle.

3. Hot Gas refrigerant pressure too low.

4. Defective timer or pressure regulator.

5. Excessive air/moisture infiltration resulting in unreasonably high frost load.

6. Fan still operating during defrost

POSSIBLE SOLUTION

1. Adjust the timer for more defrost cycles.

2. Adjust for increased defrost duration.

3. Adjust the pressure regulator/back pressure regulator for increased pressure. Check condenser fans/pumps for proper operation.

4. Replace timer/regulator.

5. Consider some form of air/moisture infiltration mitigation, i.e. dock conditioning, air curtains, improved doors

6. Cycle fans off during defrosting. Check to defrost timer or other fan control device for proper operation