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When a refrigerator’s compressor runs continuously for days and the cabinet still isn’t holding temperature, the compressor is rarely the part that’s actually broken. More often, the fridge is being told the wrong temperature. A single small sensor — the thermistor — is the fridge’s thermometer, and when it drifts out of calibration, the control board keeps calling for cooling that the cabinet doesn’t need. This is exactly what a homeowner in the Aspen Woods community of SW Calgary was living with: a Frigidaire refrigerator (model FPRH19D7LF1) that had been “not working as it should,” with a compressor that had been running non-stop for more than a week. TechVill technician Boris traced the fault to a failing thermistor and a main control board that could no longer be trusted to act on the sensor’s signal.
The Problem – A Compressor That Never Rests
The customer’s original complaint was general — the fridge simply wasn’t working the way it used to. On site, that vague symptom resolved into something specific and measurable: the compressor had been cycling continuously, without the normal rest periods a healthy refrigerator relies on, for over a week. A compressor that never shuts off isn’t a compressor working “harder” — it’s a compressor that’s never receiving the signal to stop, which drives up energy draw and shortens the life of the sealed system it belongs to.
A refrigerator doesn’t decide when to cool based on how cold the air feels. It decides based on a resistance reading. That reading comes from the thermistor, and if the number the thermistor reports doesn’t match the true cabinet temperature, everything downstream — compressor run time, defrost timing, evaporator frost — follows the wrong instruction.
Diagnosis – The Fridge’s Thermometer Was Lying
A thermistor is a temperature-sensitive resistor. Its resistance changes in a precise, known curve as temperature rises or falls, and the main control board reads that resistance to work out how cold the cabinet actually is. When the thermistor’s curve drifts — from age, moisture ingress, or internal degradation — it reports a temperature that is warmer than reality. The board, acting in good faith on a bad number, keeps the compressor running to chase a target it has, in fact, already reached. That is the mechanism behind a non-stop compressor on a fridge that feels cold inside.
Boris opened the evaporator compartment to reach the thermistor and inspect the coils. The frost pattern told its own story: frost had formed only on the entry coils rather than spreading evenly across the evaporator — a partial, progressive pattern consistent with a cooling system being run on faulty temperature information rather than a sealed-system leak. The thermistor was confirmed as failed. But the diagnosis didn’t stop at the sensor. Given the continuous-run behaviour and how the symptoms had progressed since an earlier visit, the main control board itself was no longer reliably translating the sensor’s signal into correct cooling commands. The right-sized fix here was both parts together: replace the thermistor so the board receives an accurate reading, and replace the control board so an accurate reading is actually acted on.
The Repair – Sensor and Control Board, Nothing More
Based on the diagnostic findings, Boris replaced the two components at the root of the fault. Both are genuine Frigidaire OEM service parts from the Electrolux family catalogue.
Components replaced:
- Thermistor (part #297110400) — the cabinet temperature sensor whose resistance curve tells the control board how cold the fridge actually is
- Electronic control board (part #297326500) — reads the thermistor and governs compressor run time, so cooling matches the true cabinet temperature rather than a mis-reported one
A right-sized scope, documented. During the visit the customer also mentioned the interior light staying on constantly. Boris checked the light switch: removed from the housing it tested fine, but once reinstalled it failed to cut off, pointing to a fault at the contact rather than inside the switch. The correct part was identified (Frigidaire light switch assembly, part #216822900) and an optional add-on quote was offered. The customer reviewed the cost and declined that portion of the work. It was recorded on the work order and left out of the repair. Nothing was replaced that the customer hadn’t agreed to — the fridge left the visit fixed on the fault that mattered, with the optional item transparently documented for a future decision.
The Result – Normal Cycling Restored
With an accurate sensor feeding a control board that acts on it correctly, the refrigerator was powered back up and confirmed operating. The compressor no longer had a reason to run without rest: the board now reads a true cabinet temperature, calls for cooling when it’s needed, and shuts the compressor off when the target is reached. The completed repair — thermistor and main control board — is covered by TechVill’s 90-day labour warranty.
What This Case Demonstrates
The lesson worth carrying out of this repair is diagnostic, not just mechanical: a fridge that runs non-stop is usually not a fridge with a failing compressor. It’s a fridge being fed the wrong temperature. Chasing the compressor — the most expensive part in the box — would have missed the actual fault and left the customer paying more to solve nothing.
It’s also why the parts a repair uses matter as much as the parts it replaces. A thermistor is defined by its resistance-to-temperature curve, and that curve has to match the board’s expectations exactly. An aftermarket sensor with a slightly different resistance curve or looser tolerance would report temperatures that are subtly off — and a board acting on subtly-wrong data produces subtly-wrong cooling: a compartment a couple of degrees warm, or a compressor that runs longer than it should. The fault the OEM thermistor was installed to fix could reappear in a quieter form. Genuine OEM parts hold the calibration the control board was designed around, which is exactly why they were used here. TechVill repairs Frigidaire refrigerators across Calgary with genuine OEM parts sourced through authorized supplier networks.
Need Frigidaire Refrigerator Repair in Calgary?
TechVill repairs Frigidaire refrigerators across Calgary and surrounding areas, including the Aspen Woods and Springbank Hill communities of SW Calgary. Whether your fridge needs a straightforward sensor replacement or a full temperature-control diagnosis, our technicians arrive with the test equipment to read the system end-to-end and access to genuine OEM parts.
Book online to schedule a Frigidaire refrigerator diagnostic with our team.
