318578506 âFrigidaire Oven High Limit Thermostat is a temperature-actuatedâ safety device used â˘in many Frigidaire electric ovens; â˘it is a⤠high-limit thermostat â˘(a temperature âcutâout) that âŁopens at a âpredetermined threshold to interrupt power to âheating circuits when âthe oven or appliance chassis exceeds a safe â¤temperature. Physically, the component is typically aâ small switch assembly with a temperature sensor or âbimetal elementâ adn spade terminals or aâ connector, âŁdesigned to be mounted⤠close âto the oven cavityâ or heating âŁelements and to operate without âuser adjustment.
Inside the appliance, the â¤high limit thermostatâ functions as âan overtemperature protection âŁlayer⢠that⣠interfacesâ with the bake/broil heating âŁelements, relay/contactor âŁor⣠control⣠board outputsand, âŁin gas units, with the gas valve⤠circuit. It is distinct from the⣠oven temperature control or probe â¤used for normal⢠temperature regulation: the high limit is aâ safety âcutâout that prevents sustained â¤overheating caused âŁby âcontrol⣠failures, blocked ventilation, failedâ fansor insulationâ breakdown. Its status âcan affect âelement energization, control error reportingand overall thermal managementand it is indeed âusually placed so it senses⢠either the⤠cavity temperature or the internalâ chassis temperature most likely to⣠indicate a hazardousâ condition.
This article â˘explains how the 318578506 high limit thermostat operates, â˘how âto determine âcompatibility and âŁcorrectâ mounting for replacement, common failure â˘modes and symptoms to look âŁfor, practical troubleshooting â˘checksâ for âtechnicians (continuity, wiring and connector inspectionand temperature verification)and⢠considerations whenâ selecting â˘and installing a replacement part. Readersâ will gain technical context to diagnose â¤issues related⢠to overheatingâ or lossâ of heat and to make informed decisions about⣠testingâ and⢠replacing this âŁsafety component while⣠observing appropriate electrical⤠and safety procedures.
Tableâ of Contents
- Function and Role of the HighâLimit Thermostat⤠in Oven Thermal Safety and⤠Control Systems
- How the 318578506 âFrigidaire Oven âHigh âLimit Thermostat Works: Sensing Mechanism, Contact Operationandâ Integration with⣠control Circuits
- Diagnostic Indicators andâ Common â˘Failure⣠Symptoms of HighâLimit⤠Thermostat â˘Faults
- compatibility,â Replacement Considerationsand Installation Procedures⤠for⣠the â¤318578506 HighâLimit Thermostat
- Q&A
- The Conclusion
Function and⤠Role of the HighâLimit Thermostat⣠in Oven Thermal Safety and Control⣠systems
The 318578506 Frigidaire Oven High Limit Thermostat â is a â˘fixed-setpoint safety device that interrupts heater power when internal â˘temperatures exceed a manufacturer-specified threshold. Functionally âitâ is a normally-closed thermal cutout that opens at its trip temperature to prevent⢠sustainedâ overheating of the oven cavity âor control compartment; once open⢠it⣠disables the heating âcircuit until the â˘thermostat cools âbelow âits reseat temperature (or is manually reset if of âa latching â¤type).Technicians should treatâ this part as a last-line protection separate from the oven’sâ temperature controlâ thermostat and electronic â˘controlâ board: verify electrical continuity at room temperature with a meter,â confirm correct connector and âŁmounting⣠orientation,â and â˘replace⢠with the exact part or an â˘approved âŁequivalent to âmaintain correct trip characteristics and mechanicalâ fit.
In a broader thermal â˘control architecture the high-limit thermostat âŁprovides an self-reliant overtemperature interlock that âcomplements the primary temperature regulator and âthermistor/RTDâ feedback loop.â It⣠is commonly mounted â˘near heating elements or the control housing so its thermal âtimeâ constantâ reflects â¤worst-case heating scenarios; because âit⢠is a binary device rather than a proportional sensor,its role is to fail-safe rather thanâ regulate.â Typical field practice includes checkingâ for open-circuit â˘failure (oven produces no⤠heat), shorted failure (potential for overheating)andâ thermal cycling behaviour underâ load. When replacing the thermostat, isolate mains power, document âwire positionsand ensure the replacementâ maintains the same electrical rating and physical⢠mounting⢠to avoid creating a compatibility or âsafety hazard.
- Common âsymptoms: no heat (open), uncontrolled heating (failed closed), âŁor intermittent tripping under⢠normal use.
- Service checks: continuity at⤠ambient, visual inspection for heat damageand correct terminal/wire harnessâ fit.
- Installation notes: match electrical rating âand mounting; do not attempt â¤to alter trip calibration.
| item | Description |
|---|---|
| Function | Fixed-setpoint thermal âŁcutoutâ that interrupts âpower âto⢠heating elements when â¤overheated |
| Behavior | Normally closed; opens at trip temperature to protect against ârunaway⢠heat |
| Compatibility | Designed for âspecified⣠Frigidaireâ oven âmodels-confirm connector, mounting,⤠and electrical rating before replacement |
How the 318578506 Frigidaire oven High Limit Thermostat Works: Sensingâ Mechanism, Contact Operationand Integration with⤠Control Circuits
The 318578506 Frigidaire Oven âHigh Limit Thermostat is âa⣠non-adjustable safety thermostat that âŁmonitors enclosure â˘andâ insulation temperatures using a âŁbimetal sensing â¤element.â As⤠the oven temperature rises,the⣠bimetal disc flexes; at the âŁthermostat’s â˘setpoint the disc mechanically opens the electrical contacts,interrupting theâ circuitâ that supplies power to heating⤠elements orâ the control relay. In practice this component prevents runaway heat caused by failed relays, stuck cyclesor insulation faults, âand technicians verify its operation by â˘checking for â¤cold continuity and visually inspectingâ the mounting and terminal connections before replacing it with a â¤partâ that⢠matches the original setpoint â˘andâ terminal style.
Theâ contact operation is⤠typically normally-closed â¤during normal operation and opens on anâ over-temperature â¤condition, âŁplacing the high-limit inâ series with either â¤the heaterâ power line â˘or the control board’s relay coilâ so⤠heat calls are⤠blocked⢠immediately when âit trips. â¤Integrationâ details matter: some ovens⢠use the high-limit purely as a hard⣠cutoutâ inâ the element circuit,⤠while others routeâ the switch to the controlâ boardâ so aâ fault can be⢠logged and user-interface lockouts applied. For⤠troubleshooting and compatibility âchecks,measure âcontinuity atâ ambientâ temperature,compare the stamped setpoint and terminal arrangement to the replacement,and inspect wiring forâ signs ofâ overheating or corrosion;⤠replacing the thermostat âŁwith â¤a unit of incorrect setpoint orâ terminal type âcan leave the oven unprotected or nonfunctional.
- Common diagnostic checks: cold continuity test, visual âcontact inspection,⣠compare stamped setpoint, verify correct terminal type and mounting location.
| Item | Description |
|---|---|
| Setpoint | Fixed âtemperature âŁat wich contacts open (match OEM rating) |
| Contact type | Normally-closed bimetal switch that opens on over-temperature |
| Typical terminals | Spade lug or screw terminals; â˘verify physical fit and wiring polarity |
Diagnostic âIndicators and Common Failure âSymptoms of⢠HighâLimit âThermostat Faults
The 318578506 Frigidaire â¤Oven High Limit Thermostat â˘is a âŁsafety cutoff device that monitors internal oven temperature â¤and opens⤠its internal âswitch when a predetermined overâtemperature condition occurs. In operation it âis typically a normallyâclosed bimetal or thermal switch mounted near the oven cavity or heating element; when the âsensing element⣠reaches its trip threshold the âcontact opens to interrupt the heating circuit or âŁsignal the control â˘board,â preventing sustained overheating.Compatibility is⣠modelâspecific-this part is used as a direct âreplacement in â˘many Frigidaire ranges and wall ovens but should be crossâreferenced with the appliance model numberâ or serviceâ manual to ensure matching mounting,terminal âtype,and trip characteristics.
Technically, common failure modes includeâ a contact that has failed open at ambient temperature, a contact âthat opens intermittently⤠under loador a sensor that trips atâ too lowâ a temperature. For practical diagnostics, first disconnect mains power and then check continuity acrossâ the thermostat terminals with a multimeter; a healthy âŁhighâlimit thermostat âwill⢠show âcontinuity â˘(near 0 â¤ÎŠ) âŁat room temperature and will⣠open (infinite resistance) when deliberately heatedâ above âŁitsâ trip point â˘duringâ a controlled test. Observable symptoms â˘useful to technicians and owners include â˘the âoven ârefusing to heat, premature shutdownsâ during bake cyclesor unstable thermostat control leading to wide temperature swings; verify wiring, connectorsand any related limit switches⤠or controlâ board inputs before replacing the partâ to confirm the thermostat is⤠the âroot cause.
- Oven will ânot heat at⤠all (no continuity at room temp)
- Oven heats âthen suddenly⤠shuts off (intermittent open)
- Inability⢠to reach or⤠maintain target⤠temperature (nuisance tripping)
- Error codes orâ control lockouts indicating overâtemperature or â¤sensor â¤faults
| Item | Description |
|---|---|
| Normal state | Normally closed at ambient; âŁconducts to allow heating under normal âoperation |
| Failed open | Shows no continuity at room temperature; oven âwill not â˘heat |
| Test method | power â¤off, disconnect wires, â˘measure continuity; heat âsensor⤠to verify opening behavior |
Compatibility, Replacement Considerationsandâ Installation Procedures âŁfor the 318578506⢠HighâLimit Thermostat
The 318578506 Frigidaire Oven High Limit⢠Thermostat is a temperatureâsensitive safety âcutout that interrupts the oven’s control circuit when local⤠temperatures exceed its calibrated trip⢠point, protecting insulation, â˘wiringandâ electronic controls. âIn normal conditionsâ the device is a âclosed contact at âambient temperature and opens when âthe sensing⤠element âŁreaches the limit⢠temperature; some versionsâ also âinclude âa manual reset. âCompatibility⤠depends onâ matching mechanical â¤mounting, terminal type and spacingand theâ device’s specified âŁtrip temperature, âsoâ technicians should verify the replacement part’s physical dimensions and electrical characteristics â¤against âthe originalâ before installation to ensure proper âbehavior inâ the â˘oven environment.
When replacing the âhighâlimit thermostat, follow safe⤠electrical practices and confirm âŁthe replacement matches the original’s trip characteristics and mounting âstyle.Typical installation â¤steps include removing theâ oven access panel, documenting â˘and disconnecting âŁthe wiring,â measuring cold continuity âŁwith an ohmmeter⣠(normally⣠closed should read low resistance at ambient), fitting the new thermostatâ so the sensing element has the same contact withâ the oven â˘chassis⢠or insulationand then restoring power to⣠observe normal operation; after installationâ perform an operational check by⤠running a âbakeâ cycle and verifying stable control and no nuisance cutouts. If the original part was âŁmanualâreset, select a likeâforâlikeâ replacement; â¤ifâ the oven exhibited overheating âor intermittentâ shutdowns, also inspectâ adjacent insulation andâ control relays to rule âŁout â¤secondary causes.
- Power⣠off: Disconnect mains â¤before accessing internal⢠parts.
- Document terminal labeling and â¤take photosâ of wiring âbefore removal.
- Measure continuity at âambient; âexpect aâ lowâohmâ reading if normally closed.
- Match mounting bracket,⤠terminalâ typesand trip temperature whenâ sourcing a replacement.
- Secure sensing element so it contacts the same chassis point andâ does not touch heating elements.
- Perform⣠aâ functional bake âŁtest after reassembly to confirm correct operation.
| Item | Description |
|---|---|
| Function | Overâtemperature â¤safety cutout that opens â¤the âcircuit at a specified trip temperature. |
| Mounting & terminals | bracket or clip mount; spade or â˘screw âterminals-must match original âspacing andâ connector type. |
| Test/expected continuity | Normally closed at ambient (low ohms);⣠opens when heated to the rated limit-verify â¤with controlled heating âand multimeter. |
Q&A
What âis⣠the 318578506 âFrigidaire Oven âHighâ Limit Thermostat and what does it do?
the 318578506 is âa highâlimit â(safety) thermostat used on âsome Frigidaire ovens. It isâ a fixed bimetal â˘temperature âŁcutoff switch that⤠opens when the oven or⢠control âcompartment â¤reaches an unsafe high temperature. Its âjob is⢠to interrupt power toâ theâ heating circuit (or signal âthe control) to prevent overheating and potential fireâ or component⢠damage.
How do I know if 318578506 is⢠the correct replacement part âfor my oven?
Confirm the oven’s full modelâ number (usually on a âtag inside the oven âdoor frame or behind the â˘kickplate) and crossâreferenceâ it⢠with Frigidaire parts âŁlists or an⢠authorized parts dealer. Compare the âŁpart number, mounting⤠style, âŁelectrical connector type (spade size/quantity)and physical dimensions.⢠If in doubt, use⢠Frigidaire’s official âparts â¤lookupâ or â˘contact â˘support â¤to verify compatibility before buying.
What â˘are common symptoms⤠of âa failing highâlimit âthermostat?
Typical symptoms include the ovenâ refusing to âheatâ at all, the bake orâ broil element not receiving power, the oven shutting off midâcycleor âŁthe control reporting an â˘overâtemperature fault. â˘A failed âhighâlimit most commonly fails âopen (noâ continuity), which prevents⣠the⣠heating circuitâ from energizing.
How can I test the highâlimit thermostat safely?
always disconnect power to the appliance before â¤testing. âAccess the thermostat and disconnect its wires.With a â¤multimeter set to continuity or low ohms, check âŁacross the two⣠terminals at room âtemperature-a healthy âŁhighâlimit is normally closed and should show continuity (near⤠zero ohms). Gently heat the sensor portion⣠(hairâ dryer, heat gun at distanceor controlled⢠heat) and watch the meter:⢠itâ should open (lose continuity) when it reaches its trip⣠temperature. If itâ never shows continuity âwhen coldâ or ânever opens when heated,â it should be replaced.
Can I âŁadjust or calibrate the⢠318578506 thermostat if⢠my oven temperature is⣠off?
No. The highâlimit thermostatâ is a⤠fixed â¤safety device and is not intended for temperature calibration. â˘If your oven is running âtoo hot or too cold for normal â˘cooking, âthe cause is usually the oven âthermostat/sensor or the âelectronic control, not theâ highâlimit. Replace the⤠highâlimit only if it fails its âsafety function.
How âdo I replace the 318578506 âhighâlimit thermostat?
Turn off and disconnect power to the⤠oven (unplug or switch off âŁthe circuit breaker). Removeâ access â¤panels to reach the thermostat, note or label wireâ positions, then disconnect the spade terminals and remove the mounting screw/bracket. Installâ the new thermostat in the same orientation,â secureâ itand reconnect â˘the wires âto the same⣠terminals. âReassemble panels, â¤restore power, âand testâ the oven. If you’re not comfortable working on â˘electrical appliances, hire âa qualified â˘technician.
Are there âŁspecial wiring or⢠connector considerations⢠when⣠replacing âŁthis part?
Theâ highâlimitâ typically uses â¤1/4″ (6.3â mm)⢠spade terminals. Make sure terminals are clean and âfully seated; replace⤠any corroded or⢠loose connectors.Ensure heatâresistant wiring âis used if âŁyou need to⣠replaceâ pigtails. Always match the original⤠wiring configurationâ so âŁpolarity and⣠grounding (where⢠applicable) remain correct.
Where can â¤I buy the â318578506 and how⤠much â˘should I expect to pay?
You can buy âpart 318578506 from Frigidaire/Whirlpool authorized parts⢠dealers, appliance parts websitesand some⣠online marketplaces. Prices vary by⣠vendorâ but typically fall in aâ modest rangeâ (frequently âŁenough under $60). Forâ safety and fit, prefer OEMâ parts or verified equivalents and verify return policies in caseâ the part is not compatible with your specific model.
The Conclusion
The â¤318578506 Frigidaire ovenâ high limit thermostat serves as a âŁcritical safety â¤and performance component, â¤monitoring internal oven temperature and âŁinterrupting heat if temperatures âŁexceed â˘designed limits. By providing reliable overheat protection, this âthermostat helps preventâ damage to oven elements and wiring, reduces the risk âof â¤fireand supports consistent cooking resultsâ by maintaining safe operating conditions.
timely and accurate diagnosis is essential to distinguish thermostat failure from othre âpotential causes of temperature or safety âissues; â˘replacing âŁthe thermostatâ should be done only âwhen testing indicates it is necessary and with a compatible, quality âreplacement. Relying on â˘manufacturer guidelines or a qualified service technician for evaluation and installation âŁhelps âensure⢠the âproblem is fully âŁresolved and âmaintains appliance safety and longevity.
Professional Appliance Service
If your appliance requires professional diagnosis or repair, visit
Revolff Home Services
for expert appliance repair services.
For local appliance service information see
Dryer repair Henderson
.
Replacement parts for many appliance models can also be found at
Reliable-Parts-Hub
.
Recommended Products
