Resources

Ice build-up inside refrigeration systems

Background:

Ice build-up on the evaporator coils (inside the refrigeration unit, behind the cooling fans) is sometimes caused by excessive warm and humid air coming into the unit. The warm air turns into condensation which turns into ice buildup behind the coils and into the fans. The ice makes it difficult for the compressor to cool the unit, so it runs continuously and as a result keeps building up the ice and temperature keeps going up - a snowball effect. This happens mostly during summer when temperature and humidity are high but can also happen during other seasons. If unattended long term it may cause damage to the compressor and other components.

Cause

Warm air entering through the door can be caused by:

• Door not closing properly
• Door gasket is damaged
• Door sweep is damaged
• Door closer is not functioning properly
• Door left open for extended period of time (several minutes)

Setting the thermostat to a lower than standard temperature will make the compressor run continuously and will also build up ice the evaporator coil. In turn it will have the opposite effect than you were looking for - the unit will eventually get warmer.

• Coolers should be set to: 35-38F or 2-5C
• Freezers should be set to: 0F or -18C

Note that there are many other causes related to ice build up in the system such as defective defrost timer, elements, defrost termination switch, thermostat, refrigerant leaks, Setting thermostat to a lower setting than standard and others. We are not covering those here.

Prevention

Reasons you might need to have the door open:

• Load new product
• Clean the unit
• Perform inventory audit
• Or any other reason

If you know ahead of time that you'll need the door open for an extended period of time, turn off the compressor and leave it off until you’re done with your activity. This will prevent the ice from building up. Once done, close the door and turn the compressor back on again.

How to turn the compressor off

Shut down the compressor / condensing unit (compressor is one of the components inside the condensing unit, sometimes located away from the refrigeration unit).
Stopping the condensing unit can be done by:

• Adjusting the thermostat to higher than room temperature (80F, 30C) to prevent the compressor from turning on
• Power down the compressor (condensing unit) at the electrical panel or at the condensing unit
• For smaller units, unplug it

For walk-in units, where possible, keep the evaporator coil turned on (large component mounted on ceiling inside the walk-in with the fans). If the power breaker turns off both the condensing unit and the evaporator coil, that’s ok. The key is the compressor needs to be turned off to prevent ice build up. Leave it like that for the duration of your activity. Once done return the thermostat to the original setting and/or power unit back up.

Melting the ice:

1.  Power down the compressor as per above instructions.
2.  Move product to another unit if possible.
3.  Spray hot water from a handheld bottle onto the ice to melt it. You must  never use a water hose connected to city water or anything high pressure that may damage the coils. Also, never ever chop away at the ice. Spraying hot tap water is ideal (not bowling water). Remember the evaporator coils and fins are fragile and expensive to replace.
4.  Leave unit off until all the ice is completely melted. It might require to be off overnight.
5.  Check for ice behind the evaporator coils (behind the fans inside the cooler/freezer) and inside the condensate pan under the fans. All ice must be completely gone prior to turning the unit back on otherwise the ice building cycle will start up again.
6.  Once all the ice is completely gone, power up the unit (or return the thermostat to its original setting) and monitor the temperature until it comes down to proper temp. If it does not reach proper temp, call us and we'll send a technician to diagnose the problem.