Freezers & ice makers

Freezer hums but doesn't cool

A humming freezer that isn't cooling usually means the compressor is trying to start but can't, most often due to a failed start relay or capacitor rather than the compressor itself.

Difficulty
Professional only
Time
N/A - professional diagnosis
DIY cost
$0
Pro cost
$200–$500

Symptoms

  • Steady or intermittent humming sound
  • No cold air felt near the vents
  • Hum may stop and restart every few minutes
  • Unit feels warm to the touch on the back or sides

Likely causes

  • CommonFailed start relayThis small component helps the compressor start; when it fails, the compressor hums but never kicks in.
  • PossibleWeak or failed start capacitorThe capacitor provides the extra push needed to start the compressor motor.
  • PossibleCompressor motor winding failureInternal motor damage can prevent the compressor from starting even with good relay and capacitor.
  • Less commonSeized compressorA fully seized compressor will hum and draw current but never run, usually at end of life.

What to do

  1. Unplug the unit for about 5 minutes to let it reset, then plug it back in and listen for a normal start.
  2. Feel the compressor area (bottom back of the unit) for excessive heat, which can indicate a stuck start attempt.
  3. Do not keep repeatedly plugging and unplugging, as this can further stress the compressor windings.
  4. Note whether the humming is continuous or cycles on and off every few minutes, which helps a technician diagnose faster.
  5. This repair involves testing electrical components with the unit open, which is best left to a professional.
  6. Weigh the cost of compressor-related repairs against the age and value of the unit before committing to a fix.

Tools and parts

Compressor start relay and capacitorSearch: “refrigerator compressor start relay capacitor”

When to call a pro

Humming without cooling almost always needs a technician to test the start relay, capacitor, and compressor windings.

Safety

Use caution

Do not open the compressor compartment or attempt electrical testing yourself; this involves high startup current and should be handled by a trained technician.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.