Frigidaire Dishwasher Thermostat Replacement Guide — Cost, Signs & DIY Tips

The Frigidaire dishwasher thermostat is a hi-limit safety device — a bi-metal disc that cuts power to the heating element if water temperature exceeds 180–200°F. It is not a user-adjustable thermostat and does not control the normal operating temperature. Normal temperature regulation is handled by the NTC thermistor (sensor) and the control board. The hi-limit thermostat is a last-resort safety device that prevents the element from overheating in a runaway condition.

How the Hi-Limit Thermostat Works

The bi-metal disc is made of two metals bonded together that expand at different rates when heated. At its trip point (180–200°F, depending on model), the disc snaps from its normal position (closed circuit, allowing current to the heater) to the tripped position (open circuit, cutting heater power). On most Frigidaire dishwashers, the thermostat is a single-use, non-resettable type — once it trips, it stays open and must be replaced.

Some models use a resettable thermostat that will close again after cooling. But if a resettable thermostat keeps tripping, the root cause (stuck heater relay, failed thermistor, restricted airflow) must be diagnosed — simply resetting it does not fix the underlying problem.

Location

The hi-limit thermostat mounts near the heating element, underneath the tub floor. It is accessed by removing the bottom kick panel (2 Phillips screws + spring clips). The thermostat is a small disc (about 1 inch diameter) mounted to the tub or the element housing with a single screw or clip, connected by 2 wires.

Symptoms of Hi-Limit Thermostat Failure

The tricky aspect of thermostat failure is that it mimics a heating element failure — both cause "no heat" symptoms.

• Dishes not drying — no heat during the dry phase. The thermostat has tripped and cut power to the element, even though the element itself is functional
• Water not hot during wash — same cause. No power reaches the element because the thermostat circuit is open
• Dishwasher stops mid-cycle without an error code — on some models, the board interprets the sudden loss of heater current as a normal cycle completion rather than a fault. The cycle appears to end prematurely
• Thermostat tripped after a power surge — the surge caused a momentary overcurrent in the heater circuit, which triggered the thermostat. The element is fine, but the thermostat is now permanently open

Testing the Thermostat

1. Disconnect power at the breaker.
2. Remove the kick panel to access underneath the tub.
3. Locate the thermostat disc — near the heating element terminal area, mounted to the tub floor or element housing.
4. Disconnect one wire from the thermostat.
5. Multimeter set to continuity: touch probes to the two thermostat terminals.
   • At room temperature, a good thermostat shows continuity (closed circuit). The disc has not tripped.
   • No continuity (open circuit) at room temperature = tripped thermostat. Replace it.
6. While you have access, also test the heating element (see heating element guide for resistance specs) — they often fail together.

Thermostat Cost

The thermostat is one of the cheapest parts in the dishwasher. At $8–$20 for the part, it is worth replacing proactively whenever you replace the heating element.

Replacement Procedure

1. Disconnect power.
2. Remove the kick panel.
3. Locate the thermostat — small disc near the heater area.
4. Disconnect both wires (note which terminal each wire attaches to — photograph before disconnecting).
5. Remove the mounting screw or clip and pull the thermostat off the tub surface.
6. Place the new thermostat in the same position, ensuring full surface contact with the tub floor (it needs thermal contact to sense temperature accurately).
7. Secure with the mounting screw/clip. Reconnect both wires.
8. Reinstall the kick panel. Restore power.
9. Run a complete cycle with heated dry to verify the element heats and the thermostat does not trip.

Tools: Phillips #2, multimeter, possibly a 1/4-inch nut driver. Time: 10–15 minutes.

Root Cause Investigation

If the thermostat tripped, something caused the water to overheat. Simply replacing the thermostat without finding the root cause means it may trip again. Common root causes:

• Failed NTC thermistor — reports falsely low temperature, causing the board to keep the element on past the safe point. Test the thermistor (see sensor guide)
• Stuck heater relay on the control board — the relay contacts welded closed, so the element stays energized even after the board tries to shut it off. The thermostat is the last line of defense
• Restricted airflow — on models with a vent, a blocked vent traps heat in the tub. The water temperature overshoots, tripping the thermostat

When to Replace Thermostat and Element Together

If the thermostat tripped because the element shorted or drew excessive current, the element is likely damaged too. Test both. Given the thermostat costs under $20 and you already have access, replace both as a preventive measure if the element is older than 8 years.

FAQ

What does the hi-limit thermostat do on a Frigidaire dishwasher?

It is a safety device that cuts power to the heating element if water exceeds 180-200°F. It prevents overheating — it does not regulate normal wash temperature.

Why is my Frigidaire dishwasher not heating?

Test the hi-limit thermostat first (continuity at room temperature). If it reads open, it has tripped. Also test the heating element (15-30 ohms normal). Replace whichever fails.

Can I reset a tripped Frigidaire dishwasher thermostat?

Most Frigidaire models use a non-resettable thermostat — once tripped, it must be replaced. Some models have a resettable type, but if it keeps tripping, diagnose the root cause.

Should I replace the thermostat when replacing the heating element?

Yes — at $8-$20, it is cheap insurance. They are in the same location and often fail together or in sequence.

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