318578506 â˘Frigidaire Oven â¤High Limit Thermostat is a highâlimit temperature cutoff device designed â˘for âFrigidaire ovens; it is a temperatureâsensitive, normally â¤closed switch (typically implemented as a bimetal disc or similar âthermal actuator) that opens at a âŁmanufacturerâspecified âoverâtemperature setpoint to â˘interrupt power â¤or signal a fault⤠condition. As a⣠safety â˘componentâ rather than the oven’s primary temperature regulator,this part isâ intended to protect the⢠appliance from excessive internal temperatures and âprevent damage to wiring,insulation,or other components.
Inside the applianceâ the highâlimit thermostat is â˘wired into⣠theâ heating âcircuit and/or the control board’s safety â¤interlock⣠path and directly interacts withâ the bake/broil⤠elements (orâ gas valve circuitry in gas models), the primary temperature sensorand the main control. When the oven temperature exceeds the thermostat’s trip threshold âŁthe â¤device opens, â¤removing drive to the heating elements or sending a fault input⣠to the⤠controller;⤠under normalâ conditions it remains closed so the temperature control system can modulate element power. The component is typically âŁmounted on the oven cavity wall, frameor control housing whereâ it senses cabinet temperature and can respond to localized â˘overheating caused â¤by failed elements, blocked venting, control faultsor insulation breakdown.
In this article readers will find a detailed explanation of how the 318578506 highâlimit thermostat functions,⣠how to determine compatibility with specific Frigidaire oven models, commonâ failure symptoms (such â¤as loss â¤of⢠heat, âintermittent shutoffs,⣠or an open continuity reading), basic âŁtroubleshooting checks a technician can perform safelyand practical replacement âconsiderations⤠(matching â˘electrical ratings, mounting and âlead length, connector types, âand postâreplacement verification). The coverage is intendedâ to give technicians, engineersand educated âappliance owners the technical context needed â˘to diagnose safety cutoff issues⤠and â¤plan⣠an⤠appropriate repair or replacement while observing standard electrical safety practices.
Table⣠of â˘Contents
- Function⣠and Role of the Oven High Limit Thermostat in Frigidaire⢠Ranges
- How the 318578506 Frigidaire Oven High âLimit âThermostat Operates Withinâ the Oven’s⤠Temperatureâ Regulation and Safety Circuits
- Diagnostic Symptoms and Failure Modes: Electrical, Thermaland Mechanical Indicators
- Compatibility, Model Fitment, Replacement âConsiderationsand Installation Best Practices
- Q&A
- Key Takeaways
Function and Role of the Oven High Limit Thermostat â¤in Frigidaire Ranges
The 318578506 Frigidaire Oven Highâ Limit Thermostat is a temperatureâsensitive âŁsafety switchâ that opens its contacts⢠when the oven cavity or adjacent control area exceeds a predetermined cutâout temperature, interrupting power to the bake element or gas control circuit. It is typically a normallyâclosed bimetal or thermal cutout mounted near the âburner, igniter assemblyor⤠control housing to detect abnormal heat. Replacement compatibility requires matching the cutâout temperature rating, connector styleâ (spade terminals),⢠physical mountingand reset type to âŁthe â˘specific Frigidaire range model to ensure proper operation and safe integration âwith the oven control system.
functionally, the device remains closed under normal â˘operatingâ temperatures and opensâ to deâenergize heating circuits âduring an âoverâtemperature event caused â˘by âfailed control components, âblocked ventilationor sensor faults. Troubleshooting includes visualâ inspection âfor heat â¤or corrosion, measuring âŁcontinuity â˘at â˘ambient temperature (expect closed) and verifying it opens when heated above its specification,⢠and confirmingâ whether the⤠unit is automatic or manual reset.⣠Practical considerations for âtechnicians includeâ matching terminal spacing and mount orientation during replacement, verifying identical âthermal cutout specificationsand performing a postâreplacement operational test toâ confirm correct interaction with the oven thermostat and control board.
- Common symptoms of aâ failed high limit: oven shuts off âunexpectedly, no heat despite control inputor oven stays off until part is replaced.
- Diagnostic checks: continuity at ambient, visual signs of overheating,â verify terminalâ connections and insulation.
- Replacement â˘checks: match cutâout⤠temperature, terminal type, reset behaviorand mounting⤠location.
| Item | Description |
|---|---|
| Cutâout temperature | Specified overâtemperature threshold (match original part rating) |
| Terminal type | Fastâdisconnect spade âterminals (verify size âand spacing) |
| Reset type | Automatic or manual (confirm before â˘replacement) |
| common mounting | Adjacent to bake burner/igniter or control housing |
How the 318578506 Frigidaire Oven High âLimit Thermostat â˘Operates Within the⣠Oven’s Temperature âRegulation and Safety Circuits
318578506 Frigidaire Oven High âLimit Thermostat ⣠is â¤a bimetal/thermal cutoff style âsafety device⣠mounted in the oven cavity that interrupts power toâ the bake/broil âcircuits when temperature exceeds a⣠designed⣠threshold. It does not control normal cyclic temperature regulationâ – that âfunction is â˘handled⤠by the â˘oven thermostat or electronic âcontrolâ – but âit provides a âŁnon-programmable, âfail-safe â˘cutoff â˘to prevent âŁsustained overheating.The device is typically wired inâ series with âthe heating element or â˘the control relay⢠coil so that when â˘the internal âsensing element reaches its setpoint, âŁthe contacts open âŁand remove mains power from the⢠heating âŁcircuit;⣠some variants⣠are automatic-reset bimetal types while â¤others are â˘single-use thermal fuses, âso⤠replacement must match the original part type and electrical ratings for safe compatibility with the oven model.
In practical service and troubleshooting, â˘the high limit thermostat âis checked for continuity at room temperature and for proper open behavior when âheated; an always-open unit will produce a âŁno-heat symptom, while â˘an always-closed â¤or failedâ unit may allow unsafe over-temperature events if â¤the primary control also fails. On many⤠Frigidaire models the part plugs âŁinto a âŁharness or screws intoâ a terminal block, so verify âterminal style, mounting locationand voltage/current rating âŁbefore installation. Examples: if the oven stops heating mid-cycle and the control board âshows âelement command without voltage at the element terminals, the high limit may have opened; conversely, intermittentâ heating that continues past set temperature suggests the high limit did not open when it should have.For quick reference, common checks and âindicators are listed below.
- Fails open: oven will not heat and willâ show no continuity at the thermostat at roomâ temp.
- Fails closed: risk of overheating if primary thermostat/control fails; may require temperature verification under load.
- Service check: measure continuity at room temperature, inspect mounting and connector compatibility, replace with same⢠type and rating.
- Installation: match terminal style (spade/screw), mounting bracketand reset type (automatic/manual/one-time âfuse).
| Item | Description |
|---|---|
| Function | Secondary, non-modulating safety cutoff that interrupts heating when the oven exceeds its⤠design âŁthreshold. |
| Behavior | Normally closed at⣠ambient; â˘opens on over-temperature. May be⤠automatic-reset bimetal or single-use⢠thermalâ fuse. |
| Compatibility | Must match the oven model’sâ electrical rating, terminal typeand â˘mounting to ensure safe replacement. |
Diagnostic âŁSymptoms and Failure Modes: Electrical, Thermaland Mechanical Indicators
The 318578506 Frigidaire â¤Oven⢠High Limit Thermostat is⤠a safety cutout that remains normally closed at ambient temperatures and⣠opens its contact âwhen a âpredefined over-temperature condition is âreached, interrupting power to â˘the heating circuit or signallingâ the control to disableâ the element. In â¤practice this componentâ uses a bimetal or thermal fuse element whose electrical continuity can be measured⤠with a multimeter at room temperature; loss â¤ofâ continuity at⣠room temperature or an open circuit under normal conditions indicates anâ electrical failure.Compatibility is steadfast by the âpart’s âtemperature trip point,terminal type,and mounting orientation -⣠replacements must match the original thermostat’s specifications⣠to⢠preserve intended safety â¤margins and reliable interaction with â˘the âoven control and âheating elements.For example, an oven that runs fine⣠for short cycles but cuts out âduring âextended high-temperature bakingâ frequently⣠enough points to a high-limit that⢠trips below its rated threshold or an intermittentâ contact that opens under thermal âstress.
- Oven fails to heat at all – high-limit âshows open continuity at â˘ambient.
- Oven heats briefly then shuts off during long bakes âŁ- thermostat might âŁpotentially be tripping prematurely due âto driftâ or poor ventilation.
- Intermittent heating â˘or erratic cycling – loose terminals, carbon trackingor internal contact wear.
- Visible discoloration,⣠melted terminalsor âscorched wiring â¤- evidence of overheating orâ high-resistance connections.
- Control shows an over-temperature fault or disables bakeâ while broil still works – series safetyâ device opened or control âlogic â¤sensing extreme temperature.
Electricalâ failure modes include open circuits from internal breakage, high resistance at terminals from âcorrosionor shorts to chassis/ground; thermal failuresâ manifest as calibration drift (trip at⤠lower than⢠specifiedâ temperature) or one-shot fuses that âhave operated and mustâ be replaced. Mechanical⤠issues include bentâ or broken⣠mounting tabs, crushed element housings that alter âthermal responseand loose spade connectors that create intermittent â¤failures under âvibrationâ or thermal cycling. Effective diagnosis pairs⣠a visual inspection (terminals, harness, â¤surrounding insulation) with a continuity test at â˘ambient and, if available, âa controlled heat test to confirm the⤠open point matches âŁthe rated trip behavior.Replace with a unit âthat matches the original thermostat’s trip rating and terminal styleand verify the rest of theâ circuit (control relays, oven sensorand heating element) âto prevent repeated failures caused by upstream faults.
| Item | Description |
|---|---|
| Normal⣠state | Closed at ambient; continuity â¤present until predetermined trip temperature is reached. |
| Diagnostic check | Measure âŁcontinuity at ambient; inspect terminals for heat damage; perform controlled heat verification if safe. |
| Common â¤failure causes | Internal â˘open⢠circuit, contact wear, âcorrosion⣠at terminals, â˘mechanical deformationor âthermal calibration drift. |
compatibility, Model Fitment, Replacement Considerationsand Installation Best Practices
The 318578506 Frigidaire Oven⢠High Limit Thermostat âis a⣠non-adjustable safety device âŁdesigned to interrupt power to heating âcircuits if the oven temperature exceeds a preset threshold. â˘Functionally it is indeed âa bimetalâ high-limit that opens under sustained over-temperature conditions rather than cycling⢠during normal thermostatâ control. Compatibility depends on mechanical fit âand âŁelectrical interface:â the correct replacement must â¤match⤠the mounting flange, probe âlocation or welland terminal type (commonly twoâ spade connectors on many Frigidaire ranges).When⢠evaluating fitment,â compareâ the physical â˘dimensions, terminal â˘spacingand whether⣠the original assembly includes insulating grommets or âŁheat shields thatâ locate the sensor relative⢠to the oven cavity and âheating elements.
Replacement considerations and installation bestâ practices focus â¤on preserving sensor orientationâ and electrical integrity. â˘Before replacing, isolate mains power, document or⣠photograph harness â¤connections, â¤and confirm the original part’s failure modeâ with a continuity check atâ ambient temperature; aâ properly functioning high-limit will typically show continuity âat room temperature and open when heated pastâ its trip point. During installation,transfer any sealing gaskets or shields,secure the thermostat with the original fastenersâ to⢠maintain âprobe positioning,avoid bending or flexing the sensing element,and⤠verify operation with a controlled heat cycle rather⢠than relying solely on visual inspection. â˘If an oven continuesâ to overheat after âinstalling a correct-fitâ thermostat, inspect the temperature control/relayâ components andâ wiring for faults⢠rather than assuming repeated thermostat failure.
- Confirm terminal âtype⢠and spacing⤠match the harness before ordering a replacement.
- Perform⢠ambient continuity and post-install functional heating test.
- Preserve or⤠replace insulating grommets âand heat shields âto maintain accurate sensing.
- Document connections and âtorque fasteners â¤to avoid⣠mechanical stress on the sensor.
| Item | description |
|---|---|
| Type | Non-adjustable bimetal high-limit thermostat (safety cutoff) |
| Electrical interface | Two âspade terminals (verify⢠polarity â¤not required;â correct spacing âneeded) |
| Fitment notes | Match mounting flange, âprobe/well depthand any insulating hardware toâ ensure accurate operation |
Q&A
Whatâ is the 318578506 Frigidaire oven High âLimit Thermostat and what â¤does itâ do?
The 318578506 âis a high-limit thermostat (thermal cutoff / âsafety thermostat) used on certain Frigidaire ovens.It is a normally closed⣠temperatureâsensing switch that opensâ when⣠the oven or aâ specific component âexceeds its â˘safe temperature.â its purpose is âto cut⤠power to heating⣠circuits or send âŁa â¤fault signal to the control to prevent overheating and fire risk.
Where is the âhigh âlimit thermostat⢠typically located in the oven?
Location varies by model, but the high limit thermostat is commonly âmounted ânear the bake or broil element, on the burner housingor on the back or â˘side wall of the oven âŁcavity or rear panel.You usually need to âremove the oven back panel, flame broil shield or inner cavity â¤access panel to see and access it.
how can I tell if the high limit â¤thermostat (part 318578506) has failed?
Common symptoms are the⢠oven not heating âat all, âintermittent â˘heatingor the oven shutting off unexpectedly while showing no error from the main thermostat. Theâ proper diagnostic step âis to kill power, disconnect the thermostat’s wiresand check âcontinuity with a multimeter: at room⤠temperature a normally closed high-limit should show âŁcontinuity âŁ(near 0 ohms). If⤠it is open (infinite resistance) âŁat room temp,â it has failed and should be replaced.
How do I test the âŁhigh limit thermostat safely with a multimeter?
Turn âoff power to the range atâ theâ breaker and verify power is off. Disconnect the thermostat wiring so you’re only testing âthe part. Set a multimeter to continuity or low ohms. Place probes on the two terminals: a⢠good normally closedâ thermostat willâ show continuity (close to 0-a few ohms). Do not test with power applied. If â¤you need to test operation at temperature, use âcaution – heating tests should be done by a qualified technician with proper âtools; do âŁnot bypass the device for normal operation.
Can I⢠bypass orâ jump âthe⣠high limit thermostat to get the ovenâ working?
No – âyou should not bypass the high limit â˘thermostat for normal operation. It is a safety device; bypassing⢠it removes overheat⤠protection and⣠creates a⤠serious fire and injury hazard.A qualified technician may temporarily jump a circuit for controlled diagnostic âpurposes, but the â˘part âŁmust âŁbe replaced before returning the appliance to service.
Is the â¤high limit thermostat adjustable or recalibratable?
No. The high⣠limit thermostat is a âfixed-temperature safety cutoff â˘and is not adjustable or recalibratable inâ the field.Ifâ it is tripping â˘when it should not âor if⢠it no longer conducts at roomâ temperature, replace it.
How tough is it to⣠replace part⤠318578506 and âwhat tools are needed?
Replacement difficulty is typically moderate. Basic hand tools (screwdrivers, nut drivers), âa multimeter for verification, âŁand possibly pliers âare⣠usually needed.Steps: disconnect power, remove the access/back panel, note andâ disconnect wires⢠from the thermostat, remove mounting screw(s), install the new part, reconnect wires exactly as they were (use highâtemperatureâ connectors if necessary), reassemble and restore âpower. â˘Allow âŁ30-90 minutes depending on your experience âand the oven model.
Is 318578506 the correct part for my â˘Frigidaireâ oven and⤠where can â¤I âbuy a replacement?
part numbers can vary⣠by⤠model and âproduction date. Always verify âcompatibility âby checking your oven’s full model number against the parts list or a reputable parts supplier. The 318578506 âŁis an âŁOEM Frigidaire part used on specific models; â¤it is â˘indeed sold byâ appliance parts distributorsâ and⤠some retailers. When replacing, prefer OEM or⣠an exact âcrossâreference to ensure correct fit and temperature rating. âAlso check warranty âŁand return policies in⣠case the⤠part⢠does not resolve theâ issue.
Key Takeaways
The 318578506â Frigidaire Oven High âLimit â¤Thermostat serves asâ a critical safety component, monitoring oven temperature and interrupting power when readings âexceed the designed threshold. âByâ protecting heating elements, internal components and cabinetry from⣠excessive heat, this thermostat helps prevent damage, reduce fireâ risk and maintain consistent cooking performance. Its reliable operation âis thereforeâ integral to both appliance safetyâ and⣠functional⢠longevity.
Accurate âŁdiagnosis is essential when⤠oven temperature problems or safety cutoutsâ occur. Confirming thermostat failure-rather than a related control, wiring or sensor issue-avoids unneeded parts replacement and âŁdowntime. When testing âand inspection âindicate âŁthe highâ limit thermostat is defective, timely âŁreplacement with the correct part restores intended protection and temperature control. For⣠complex diagnoses or replacement, consultation with a qualified appliance technician ensures safe, code-compliant work and proper reassembly.
the 318578506â Frigidaire Oven High Limit Thermostat is⢠a small âbut vital element of âoven safety andâ performance. Prioritizingâ proper diagnosis and, when appropriate,â prompt replacement helps maintain appliance reliability, protects surrounding components and preserves âhousehold safety.
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