Troubleshooting Iced Evaporator Coil

Freezer coil

How to check for an iced coil?

Sometimes an iced coil is obvious as in the pictures below – in these pictures, the ice has built up past the coil, spread past the evaporator fans and into the interior of the cabinet. Often times after ice build up the first symptoms will be a “tinging” noise which is the fan blade hitting the ice. Also, the temperature in the cabinet will drop somewhat but usually remain consistent within a degree or two – until the situation intensifies whereas the unit will no longer operate as it should. Sometimes the ice will build so bad that it will damage the evaporator fan motor, fan blade, or possibly even the coil itself – often times the expansion of ice will damage the fins of the fan blade and possibly create a whole in the coil itself.

Sometimes the ice is only built on the coil itself and may be difficult to see without removing the evaporator cover. DO NOT remove the evaporator cover!

I do recommend however taking a mirror to the back of the unit (behind the cover that protects the fans there is often times a 2-5″ gap allowing room to see the coil with a properly positioned mirror) Merely placing a mirror in position to see the coil will often reveal if ice build, frost, or snow up is present on the fins. DO NOT stick your hand up there for a feel if you do not know where to look as there are electrical components, defrost heaters, and fan motors that could hurt you.

What causes iced evaporator coils?

There are numerous reasons for the coil on a freezer or cooler to build ice. Most of these are USER RELATED and/or USER CREATED.

1. RIPPED DOOR GASKET: When a unit has a ripped or torn door gasket, the unit cannot efficiently exchange heat as the cool air leaks out – the compressor runs continuously trying to maintain box temperature but can never satisfy. This will assuredly build ice and frost the coil over.

2. DOOR LEFT AJAR: This is probably the most common and typical cause for an iced coil.
A. Sometimes the customer accidentally leaves the door ajar after grabbing a product and simply walking away.
B. Often times, something falls in the door closure area and keeps the door from closing fully.
C. I have witnessed door closure/component failure. i.e., the “self closing” spring, latch, or adjuster fails or comes out of adjustment thus preventing the door from closing properly.
D. Also, another common cause regarding the door ajar is that the unit itself is not level create a gravity type “door ajar” situation. Ensure the unit is level or even leaning towards the back a little bit will ensure proper door closure via gravity.

3. LOW ON REFRIGERANT: An iced coil can become an issue when a unit is low on refrigerant. This is when the coil cannot exchange heat equally across the fins thus creating an icing situation. Of course if you have a low on refrigerant situation, you most assuredly have a leak too!

4. IMPROPER ADJUSTMENT: This is a more technical problem and usually follows the technician that just left after charging you $300-500.00 for faulty repairs. Some freezers have what is known as a TXV valve or more commonly referred to as an expansion valve. This is a metering device used to control or regulate the amount of refrigerant passing through the evaporator. Often time “Clifford” the technician feels this may need adjustment – a lot of techs automatically and foolishly make this critical mistaken while troubleshooting a problem. If the TXV valve was improperly adjusted, as in the pictures below, it will certainly cause and create an iced coil.

5. DIRTY CONDENSER: This is the most common problem I see with FREEZERS – lack of proper MAINTENANCE such as a dirty condenser (see picture below)

6. DEFROST TIME: Several defrost issues can cause an iced coil such as:
A. Malfunctioning or inoperative defrost time clock.
B. Improper timing/programming of defrost clock
C. Insufficient duration of defrost.

A. Faulty evaporator drain heater.
B. Plugged drain tube.
C. No trap or improper vent for drain tube causing/creating air lock.

8. FAULTY or FAILED EVAPORATOR FAN: This can also include failed door switches which are designed to shut the fans off once the doors are opened thus preventing warmer more humid air to be sucked in while the doors are opened for an extended period of time.

There are other technical reasons for an iced coil but the above mentioned ones are the most common and most typical.

This an example of an iced evaporator coil. This was caused by a faulty (failed) evaporator fan motor

PICTURED ABOVE: This is one of the more common causes of an iced coil…. a dirty condensing coil….