Your deep freezer is warm inside and the food is softening. A deep freezer compressor not working is only one explanation, and it isn’t the first thing we check. When a freezer is called in as a dead compressor, we look at power first, then the thermostat or control, then the lid seal. Power problems are the quickest to rule out.

If it hums, clicks off and repeats, a failed start relay or overload protector is a common suspect, though a failing compressor can look exactly the same. Before you touch anything on or near the compressor, unplug the freezer. Start with what you hear.

Reading the Symptoms of a Deep Freezer Compressor Not Working

The sound, or the lack of one, decides which checks matter.

• Silent, no hum, no click, warm inside. Think supply or control before the compressor: the outlet, the cord, or the thermostat.
• Hums, clicks off, goes quiet, repeats. The compressor is trying to start and the overload protector is cutting it off. A failed start relay or overload is a common suspect, and it’s cheaper to check first. A failing compressor can cause the same symptom, and there’s no reliable percentage that separates the two.
• Runs but isn’t cold. It’s not always the sealed system. Dirty condenser coils, a faulty fan, a defrost failure or blocked airflow can all do it, and how often each one turns out to be the cause depends on the model.

The fan and defrost items mostly apply to upright freezers. Chest freezers are usually manual-defrost, with no evaporator fan. If it’s the fridge that’s warm while the freezer holds, that’s a different fault, covered in our post on a warm fridge, working freezer.

Five Quick Checks That Cost Nothing

Power problems are the quickest to rule out, so work through these in order.

1. Test the outlet. Plug a lamp or phone charger into the same outlet. A freezer that’s completely silent, with no light and no hum, is a power question first.
2. Check the breaker and the GFCI. Look at the breaker for that circuit and at any GFCI outlet on it, including one upstream. Garage and basement outlets are often GFCI-protected.
3. Look at the thermostat dial. A dial set to the warmest position or to off, or one knocked during loading, can stop the compressor from starting. Some chest freezers have a dial position that switches the unit off. Your owner’s manual will show yours.
4. Test the lid seal. Close the lid on a dollar bill and see whether it pulls out with no resistance. A worn seal lets in warm, humid air, so look for frost near the seal. It usually causes poor cooling rather than a completely dead freezer.
5. Think about where it sits. Freezers are rated for a limited room-temperature range, and many standard models struggle in an unheated garage. In very cold weather the thermostat may stop the compressor from running. In very hot weather the compressor runs nonstop. The manual gives the range for your model.

If all five check out and the freezer is still warm, move on to heat and the start parts.

When Heat Makes a Healthy Compressor Cut Out

A compressor that overheats shuts itself off through its overload protector, and from the outside that looks dead.

Dirt on the condenser coils restricts airflow, so heat isn’t shed. The compressor gets hotter until the overload trips. Unplug the freezer before you go near the coils, then clear the dust from them. Your manual shows where the condenser sits on your model.

A failed condenser fan motor does the same thing by stopping air from moving over the coils and compressor. Many chest freezers may have no condenser fan at all, so this applies mostly to uprights. If yours has one, our post on testing a condenser fan covers the steps.

Don’t touch a compressor that feels too hot. Unplug the freezer and leave it to cool for several hours before it’s tried again. If it overheats again straight away, a seized compressor or an electrical short becomes a real possibility.

Don’t keep resetting a tripping overload either. Repeated trips are said to wear the motor windings, so find the cause first.

Start Relay, Overload Protector and Capacitor

These are the cheap parts to look at when the freezer hums, clicks off and repeats. The same start parts fail in kitchen units too, as our post on a fridge compressor that won’t start explains. A failing relay can also show up as no cooling at all, with an occasional hum through the day, because the compressor never actually starts.

This section is for someone comfortable with a multimeter. If that isn’t you, skip to the last section.

1. Unplug the freezer and keep it unplugged for every step below.
2. Find the relay on the side of the compressor and remove it.
3. Shake it. A rattle suggests it has burned out.
4. Check continuity with a multimeter. No continuity means replace it.
5. Buy a replacement that matches the original in pin count, voltage rating and the compressor model it’s made for. A mismatch can cause a hum with no start, or an overload trip.

Treat these as a first screen, not proof, because the procedure comes from a single source and not a maker’s manual. A relay that passes doesn’t clear the compressor.

Leave the capacitor to a technician. A failed run or start capacitor also shows up as a compressor that won’t start or just hums. A capacitor stores electricity, so it needs discharging safely even with the freezer unplugged.

Is the Compressor Itself Dead?

A seized compressor usually hums or clicks once, then the overload protector trips after several seconds, and the cycle repeats. If the start relay and capacitor test good, that pattern points to a mechanically stuck compressor. It’s also the pattern a weak start part produces, which is why the symptom alone can’t settle it.

A technician settles it by measuring the windings. The resistances are very low, a few ohms, so a cheap meter can’t reliably tell slightly shorted turns from a good winding. Don’t trust a published figure unless your model’s data plate or spec sheet gives one. Windings that test fine don’t clear the compressor either.

Continuity from a winding terminal to the bare copper tubing or the compressor shell means the winding has shorted to the shell. That compressor is condemned and shouldn’t be powered up again.

A confirmed dead compressor usually ends DIY repair. Replacing one means recovering the refrigerant, brazing, fitting a new filter-drier, evacuating the system and recharging it. That’s certified work in many jurisdictions. On an older or low-value chest freezer, it often ends repair altogether. Ask for a quote before you decide.

Compressor Runs but the Freezer Isn’t Cold

A running compressor with no cooling isn’t automatically a refrigerant problem. We’d rule out the cheaper causes first: a worn lid or door gasket, heavy frost buildup, a failed or mis-set thermostat, dirty condenser coils, a faulty fan, or blocked airflow. Upright frost-free models add a failed evaporator fan or a defrost heater, timer or sensor.

If those are clear, the cause may be a low charge, a sealed-system leak or a blockage. That’s a technician’s job. Fixing it means finding and repairing the leak, replacing the drier, pulling a vacuum and recharging by weight to the nameplate charge. Topping up without finding the leak is at best temporary. Household freezer charges are very small, often a few ounces, so errors matter.

Many modern freezers also use flammable refrigerants (R600a or R290). Never braze or pierce a refrigerant line yourself.

When to Stop and Call a Technician

Stop and call for freezer repair if any of these apply:

• The freezer hums, clicks off and repeats, and the relay isn’t clearly the fault.
• The compressor shell is hot and the overload keeps tripping.
• The freezer stays warm with the compressor running after the free checks.
• The next step is a capacitor, a winding test or anything touching the refrigerant lines.

Tell us what you hear, what you’ve already ruled out, and the model number from the data plate. We serve Thornhill, so if you’re there, send those details and we’ll go from there.