Short answer
The compressor and the condenser are two different parts that work together, not alternatives. The compressor pumps refrigerant and raises its pressure. The condenser is a coil that releases heat from the hot refrigerant to the surrounding room air. In a household fridge, the condenser is often a maintenance item (dust makes it work poorly), while the compressor is a sealed-system part that is expensive to replace.
So when a refrigerator is not cooling, first check whether the condenser is dirty or its fan is stuck, because that is cheaper and safer to fix, before deciding the compressor has failed.
What each part does
Compressor. A motor-driven pump, usually a black, rounded canister near the bottom rear of the refrigerator. It draws in low-pressure refrigerant gas and compresses it into hot, high-pressure gas. It is often described as the heart of the cooling system. To learn how compressor designs differ, see types of refrigerator compressors.
Condenser. A heat exchanger made of tubing, either exposed coils on the back or underneath the unit, or hidden behind a grille. The hot gas flows through it, loses heat to the air, and condenses into a high-pressure liquid. A fan often helps move air across it.
How they work together
In simplified terms:
- The compressor pressurizes the refrigerant, which becomes hot.
- The condenser releases that heat into the room, and the refrigerant becomes liquid.
- The liquid passes through a metering device and expands, becoming very cold in the evaporator inside the freezer.
- The evaporator absorbs heat from the food compartment. The refrigerant returns as a low-pressure gas to the compressor.
If the condenser cannot dump heat, the compressor works harder and runs hotter. If the compressor cannot pump, nothing circulates.
Signs of a dirty or failing condenser
- The refrigerator runs for long periods and cooling is weak.
- The area at the back or bottom feels hotter than usual.
- Heavy dust, lint or pet hair on the coils.
- A condenser fan that does not spin or is noisy.
- Cooling gets worse in a hot room or during hot weather.
Most of these are fixable. Unplug the unit and carefully clean the coils with a brush and vacuum, and check the fan for obstructions. A physically damaged or leaking condenser is rare and a professional matter.
Signs of a failing compressor
- No cooling, even though the lights and fans work.
- Clicking, then silence, repeating every few minutes.
- No hum or vibration from the compressor at all.
- Loud buzzing, knocking or humming.
- A breaker that trips when the fridge starts.
Read the details in bad refrigerator compressor symptoms and repair options. Keep in mind that a faulty start relay or overload protector can produce the same clicking.
Side-by-side comparison
| Condenser | Compressor | |
|---|---|---|
| Job | Releases heat from the refrigerant | Pumps and pressurizes the refrigerant |
| Typical location | Back or underneath, often behind a grille | Bottom rear, black sealed canister |
| Common problem | Dust buildup, fan failure | Electrical or mechanical failure, start components |
| Homeowner action | Cleaning is often reasonable | Not a DIY repair |
| Relative cost to fix | Usually lower | Usually high |
A simple order of checks
- Confirm power, settings and door seals.
- Unplug the fridge and inspect and clean the condenser coils.
- Check that the condenser fan turns freely.
- Plug back in and listen for the compressor running and fans spinning.
- If you hear clicking or hear nothing at all, consider the start relay and overload protector, which a technician can test.
- If all of that checks out and there is still no cooling, a technician can test the compressor and look for a sealed-system issue.
The full range of causes is in our refrigerator not cooling guide.
Do I need to replace the condenser when I replace the compressor?
Not necessarily. They are separate components. A compressor can fail without damaging the condenser, so the condenser may stay in place if it is clean and sound. However, a technician may recommend replacing associated parts or the drier during a sealed-system repair, and if a compressor failure left contamination in the system, the situation can be more involved. Ask your technician what is needed for your model, and get it in writing. Because many household refrigerators use an integrated design, a full sealed-system repair is often not economical on an older unit.
Lifespan
Compressors in household refrigerators can often last many years, though the exact lifespan varies by model, use and maintenance. Condenser coils generally last a long time too, provided they are not damaged, but they need periodic cleaning (many manufacturers suggest at least once or twice a year; check your manual).
When to call a professional
Clean coils and fan checks are reasonable for many owners, with the unit unplugged. Leave the following to a qualified technician: testing electrical components under power, anything involving refrigerant lines or the sealed system, and replacing a compressor or condenser. Handling refrigerant generally requires certification, and some modern units use flammable refrigerant, so do not puncture or cut any lines.