Precision Is the Point
True refrigeration is prized for holding a tight, steady temperature, so when it starts swinging or drifting off setpoint, the fault is in the sensing and airflow that make that precision possible. A thermistor that has drifted feeds the control a wrong reading, so it over- or under-cools. A blocked vent or a failing fan disrupts the even air circulation the design depends on.
Because True uses symptom-based diagnosis rather than codes, the pattern of the swing, too warm, too cold, or oscillating, guides where to look.
Common Causes of Instability
A drifting thermistor is a frequent cause of a unit that reads right but runs warm or cold. Airflow problems, from an overloaded shelf blocking a vent to a failing evaporator fan, cause uneven and unstable temperatures. A door gasket that no longer seals lets warm air in intermittently, which shows up as swings. And a partial defrost fault can cause the coil to ice and airflow to fluctuate.
We test the thermistor, check airflow and the fan, inspect the gasket, and verify the defrost system to find which is disturbing the setpoint.
Symptom Reference
| Symptom | Likely Cause | What We Do |
|---|---|---|
| Reads right, runs warm or cold | Thermistor drift | Test and replace sensor |
| Uneven temperatures | Airflow or evaporator fan | Clear airflow, test fan |
| Swings with door use | Gasket not sealing | Replace gasket |
| Fluctuates with icing | Partial defrost fault | Diagnose defrost system |
Do Not Block the Vents
An overloaded shelf covering an internal vent is a simple but common cause of unstable temperatures. Keep air paths clear before assuming a component fault.
Book a Repair with a Specialist
Diagnostic and travel fees, if applicable, are confirmed before the appointment and before repair approval.