Clearing a Major Freezer Blockage

We headed out to a service call in Langley for a freezer that wasn’t keeping food frozen. Upon opening the back panel, this is what greeted us – a solid wall of ice encasing the evaporator coils. This massive frost buildup completely blocks the airflow, so the fan can’t circulate cold air into the compartment. The issue was a failed defrost heater and a broken bi-metal sensor. We had to manually defrost the coils, replace both components, and ensure the drain tube was clear. Now the freezer is cooling as it should, and the food is safe. A tricky repair, but essential for proper function.

What the customer reported

The call came in from Langley for a freezer that wasn’t keeping food frozen. That is the full symptom on file, and it’s a serious one, because a freezer that can’t hold temperature puts everything inside at risk. The record doesn’t say what brand the freezer was, so we’re not naming one.

The record also doesn’t tell us how long the problem had been building, so we won’t speculate on that. What it does show is what our technician found once the back panel came off.

What the diagnosis found

Behind the back panel was a solid wall of ice encasing the evaporator coils. That kind of frost buildup blocks the airflow completely, so the fan can’t circulate cold air into the compartment. The result is a freezer that runs but doesn’t cool the space where the food is.

The cause, as the record puts it, was a failed defrost heater and a broken bi-metal sensor. Two failed components together explain why the ice built up so heavily: the system that’s meant to clear frost wasn’t able to do its job.

The part and the repair

The technician had to manually defrost the coils first, since there was no way to work properly around a block of ice. Then both failed components were replaced: the defrost heater and the bi-metal sensor. The drain tube was checked and cleared as well, so meltwater can leave the freezer instead of refreezing.

Once that was done, the record says the freezer was cooling as it should and the food was safe. We called it a tricky repair at the time, and it was. It’s also the kind of fault where replacing only one of the two parts would likely have left the freezer set up to frost over again.

How the defrost system works

On many frost-free freezers, a heater near the evaporator coils switches on from time to time and melts the thin layer of frost that forms there. A bi-metal sensor, sometimes called a defrost thermostat, reads the temperature at the coils and helps control when the heater runs and when it stops. The meltwater runs out through a drain tube. The design differs between models, but if the heater, the sensor or the drain fails, frost can start to build up.

How to avoid this fault

Keep the door gasket clean and make sure the door closes fully, because warm, humid air getting in feeds frost. If you notice frost forming at the back of the compartment, call for service early instead of waiting for the freezer to stop cooling.

Why it matters

A freezer full of ice behind the panel is cooling in name only. If yours is struggling in Langley or anywhere in Metro Vancouver, ASAP Appliance Repair is based in Surrey and handles residential freezers and other major appliances.