4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit is a combined starting relay and thermal overload protector used on single‑phase hermetic compressor motors; the assembly provides a timed or current‑sensing start assist to engage the compressor’s start winding and a thermal/overcurrent device to protect the motor from sustained overload conditions. The unit is typically a small plug‑on or bracketed module mounted at the compressor terminal block and is identified by its part number for compatibility with specific Whirlpool refrigerator models.
Inside the appliance, the relay/overload kit sits in the compressor start circuit and interfaces directly with the compressor motor, the household mains supplyand the refrigerator’s control wiring. During the start interval the relay closes (or provides a high starting current) to energize the start winding and create the necessary torque to bring the compressor up to speed; once running the relay drops out and the run winding maintains operation. The overload protector interrupts power if motor current or temperature exceeds safe limits, preventing thermal damage. The component thus interacts electrically with the contactor or control board outputs and mechanically with the compressor terminalsand its condition has a direct impact on refrigerant circulation and system cooling performance.
This article explains the 4387535 kit’s functional principles, outlines model compatibility and mounting variants, describes common failure symptoms (for example persistent humming, failure to start, excessive run currentor intermittent operation)and provides a structured approach to troubleshooting and verification suitable for technicians and experienced appliance owners. It also covers practical replacement considerations, including part selection, connector and orientation checks, safety precautions when working on the compressor circuitand diagnostic steps to confirm whether the start kit or another system component is at fault before replacement.
Table of Contents
- Function and Role of the Compressor Relay and Overload Start Kit in Refrigeration Systems
- How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Operates Within the Compressor Start Circuit
- Common Failure Symptoms and Diagnostic Indicators of Relay and Overload Start Kit Malfunction
- Compatibility, Replacement Considerationsand Installation Best Practices for Whirlpool Refrigerator Models
- Q&A
- In Retrospect
Function and Role of the Compressor Relay and Overload Start Kit in Refrigeration Systems
The 4387535 Whirlpool refrigerator Compressor Relay And Overload Start Kit combines a start device and a thermal overload protector into a single serviceable module that controls compressor starting behavior and protects the motor from sustained overcurrent or overheating. The start element (a PTC or solid-state relay in many kits) momentarily connects the start winding or provides a capacitance boost so the compressor achieves sufficient starting torque; the overload monitors current/temperature and opens the circuit if the compressor stalls or draws excessive current. Match the kit to the compressor’s terminal configuration and nameplate ratings-mismatched coil characteristics or interruption ratings can cause nuisance trips or insufficient start assist.
- Start assist: brief connection or boost to start winding to overcome locked-rotor torque
- Overload protection: thermal or current-responsive device that disconnects the compressor under fault conditions
- Terminal compatibility: typically uses common, startand run terminals (C, S, R); verify layout before replacement
- Failure symptoms: clicking relays, steady hum without start, intermittent startsor circuit breaker trips
| Item | Description |
|---|---|
| Start device | Provides a timed or conditional connection to the start winding (PTC, electronic relayor capacitor assistance) to produce the required starting torque. |
| Overload | Opens the circuit on excessive current/temperature, protecting the compressor from damage during stall or locked-rotor events. |
| Compatibility checklist | Verify terminal labels, mounting method, and interruption/current ratings match the compressor nameplate before installing. |
operationally, the relay portion engages only during crank-up and then drops out, while the overload remains in series for continuous protection; common diagnostic steps include listening for the relay click, measuring continuity between start/run terminalsand observing inrush current during attempted starts. Replace the module when the compressor repeatedly fails to start, when the overload has visibly trippedor when electrical tests indicate open or inconsistent behavior-ensure safe isolation of power and confirm replacement parts meet the original equipment specifications to maintain reliable refrigeration performance.
How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Operates Within the Compressor Start Circuit
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines the electrical relay and the thermal overload protector into a single assembly that interfaces directly with a hermetic compressor’s start circuit. In operation the relay element momentarily connects the compressor’s start winding to line voltage during crank-up, allowing the motor to develop sufficient torque; once the compressor reaches running speed the relay opens to leave only the run winding energized.The thermal overload is wired in series with the run terminal and will open the circuit under sustained overcurrent or excessive temperature, isolating the compressor to prevent winding damage. This arrangement is compatible with standard three-terminal compressors and is intended to match the typical run/start/common (C, R, S) terminal configuration used on many Whirlpool systems.
functionally,the relay might potentially be a current-sensing or solid-state/thermistor-driven device depending on design,but its role is always to limit the duration that the start winding is energized to avoid overheating the start coil. The overload is a temperature/current safety that requires the compressor to cool down (automatic reset) before normal operation resumes; if the overload is repeatedly tripping, that indicates an underlying mechanical or electrical fault such as low refrigerant, seized bearingsor incorrect supply voltage. For service technicians, verify terminal identification (C, R, S), continuity and resistance values against the compressor nameplateand ensure the replacement kit’s current/voltage ratings match the compressor to avoid premature failure or nuisance trips.
- Common service indicators: humming/no spin at start, long crank time, repeated cycling or blown start capacitors when present.
- Key compatibility checks: terminal layout, amp rating, and mounting footprint.
| Item | Description |
|---|---|
| Relay action | Engages start winding during crank, disengages at run speed to prevent overheating. |
| Thermal overload | Opens under sustained overcurrent or high temperature, isolating compressor until cooled. |
Common Failure Symptoms and Diagnostic Indicators of Relay and Overload Start Kit malfunction
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit is a combined electromechanical/thermal protection assembly that provides the starting torque and thermal cutoff required by many Whirlpool compressor designs. The relay element temporarily connects the start winding (or changes phase through a PTC device) to produce the initial rotational force; the overload protector opens the circuit when the compressor draws excessive current or its internal temperature rises above safe limits. Compatibility depends on terminal layout, mounting footprint, and the compressor’s start‑current and voltage characteristics, so technicians should match the kit’s form factor and ratings to the compressor model rather than assuming worldwide interchangeability.
Typical failure modes produce distinct, measurable indicators that guide diagnosis: a bad start relay or PTC will often allow the compressor to hum without turning (locked‑rotor condition), produce repetitive clicking as the overload trips and resetsor cause elevated current draw during attempted starts. Practical diagnostic checks include visual inspection for charring or melted plastic at the terminals, a continuity/ resistance check across the relay and overload where applicableand an amp‑draw measurement with a clamp meter during startup to compare starting versus running current. If electrical tests are ambiguous,swapping a known good kit with identical specifications or bench‑testing the relay at the compressor terminals provides a definitive confirmation of failure.
- Hum without rotation and repeated clicks – suggests relay/overload cycling or failed start winding engagement.
- Burnt odor,discolored housing,or loose/melted terminals – indicates thermal or electrical overload damage.
- High inrush or prolonged elevated start amps measured with a clamp meter – indicates insufficient starting torque or failing relay element.
- Open circuit on continuity test across the overload at ambient temperature – overload protector has failed open.
| Item | Description |
|---|---|
| Function | Provides start winding engagement and thermal overload protection for compressor start sequence. |
| Quick field test | Clamp‑meter start amp measurement, continuity checksand visual inspection for heat damage. |
Compatibility,Replacement Considerations,and Installation Best Practices for Whirlpool Refrigerator Models
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit supplies the start relay and thermal overload that together initiate compressor rotation and protect the motor during abnormal current or temperature conditions.The relay provides a brief connection to the compressor’s start winding to produce the additional torque required at spin-up; the overload opens the circuit if the compressor draws excessive current or runs hot. These components are mechanical or solid-state devices matched to specific compressor families, so compatibility depends on the compressor terminal layout, mounting footprintand electrical rating rather than the refrigerator cabinet model alone.Typical field symptoms indicating a failed relay/overload include continuous humming with no run,repeated short cycling at startup,or visible arcing/noise at the relay socket.
Replacement and installation should prioritize verification and measurement over trial-and-error swapping. Before handling the start kit, disconnect power and document original wiring and terminal positions; confirm the 4387535 kit matches the compressor’s three-terminal configuration (start, run, common) and the compressor’s rated supply voltage and expected locked-rotor current. Use a multimeter to check start-winding continuity and a clamp meter to record starting amperage; if measured locked-rotor amps substantially exceed the compressor specification, replacing the relay/overload may not correct a mechanical seizure. Securely mount the overload so it senses compressor temperature as intended,use proper crimped or soldered terminal connections,and verify after installation that start timing and run current return to expected ranges.
- Compatibility checklist: part number vs compressor model, terminal layout, voltage/current ratings, and physical mounting.
- Pre-install tests: continuity of start/run windings and measurement of starting current.
- Installation best practice: secure thermal device to compressor shell,use correct connectors,and retest under normal load.
| Item | Description |
|---|---|
| start Relay | Momentary device that connects the start winding to provide initial torque; can be PTC or mechanical and must match terminal layout and switching characteristics. |
| Thermal Overload | Protective device that opens the motor circuit on overcurrent/overtemperature; must be mounted and rated for the compressor to sense actual shell temperature. |
Q&A
What is the 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit and what does it do?
The 4387535 kit is a replacement start device assembly for refrigerator compressors. It contains the start relay (or PTC/start device) and the overload (thermal protector). The relay provides an extra boost to get the compressor motor startedand the overload protects the compressor from drawing excessive current or overheating. Together they are a common service item when a compressor will not start or the refrigerator is intermittently cooling.
What symptoms indicate I should replace the relay and overload with part 4387535?
Typical symptoms include: compressor humming but not starting, repeated clicking or clicking followed by silence, intermittent cooling, refrigerator not reaching temperatureor a relay/overload that shows visible burning or a strong burnt odor. If the compressor runs briefly then stopsor will not start at all but has power, a failed start relay/overload is a likely cause.
How do I verify compatibility of 4387535 with my Whirlpool refrigerator?
Verify compatibility by checking your refrigerator model number and looking up replacement parts on the Whirlpool parts site or a trusted parts supplier. You can also visually compare the connector and mounting style to the unit on the compressor (three-terminal common/start/run style). If in doubt, provide the appliance model number to the parts supplier to confirm fitment before purchase.
Can I test the relay and overload myself before replacing them?
Yes,with basic tools and safety precautions.First unplug the refrigerator. Remove the relay/overload from the compressor terminals and inspect for visible damage. You can test the overload for continuity with a multimeter; it should show continuity when cold. Relay testing is less definitive: some relay/PTC devices show low resistance between certain terminals, but PTC elements may not give a conclusive reading. A common field test (for experienced technicians only) is to temporarily swap with a known-good relay or observe whether the compressor starts when the start terminal is momentarily bridged to run (use caution). If you are not agreeable doing these tests, have a qualified technician perform them.
What is the correct procedure to replace the 4387535 start kit?
Safety first: unplug the refrigerator before starting.Access the compressor (usually behind a rear service panel). Remove the old relay and overload from the compressor terminals-they usually pull off by the connector tabs. Fit the new kit so the overload sits against the compressor shell (if applicable) and the relay snaps into place on the same terminals. Reinstall any covers, plug the refrigerator back inand observe compressor start-up. Ensure tight,clean connections and proper seating of the overload for good thermal contact. If the compressor still fails to start after replacement, further diagnosis of the compressor or sealed system is needed.
Are there any safety or warranty considerations I should know before replacing the part myself?
Always unplug the appliance before servicing. Do not attempt sealed-system repairs (refrigerant/copper tubing) if you are not certified-those require licensed technicians. Replacing electrical parts typically does not void a manufacturer’s warranty on the sealed system, but check your warranty terms. use genuine OEM parts where possible to ensure proper fit and reliability. If the refrigerator is still under manufacturer or extended warranty, consider contacting Whirlpool or the warranty provider before performing DIY repairs.
If replacing the relay and overload doesn’t fix the problem, what are the likely next steps?
If the compressor still will not start after installing a known-good relay/overload, the next possibilities include a failed compressor (mechanical lock or internal electrical fault), a faulty main control board or start components upstreamor a sealed-system issue. Further diagnosis requires measuring compressor windings (if applicable), checking line voltage under loadand possibly involving a certified appliance technician to test or replace the compressor or service the sealed system.
In Retrospect
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit serves a critical function in the refrigeration system by enabling reliable compressor startup and protecting the compressor from electrical overload. By combining a start relay and an overload protector,the kit helps ensure smooth motor engagement,reduces mechanical and electrical stress during start-up,and contributes to consistent cooling performance and longer service life for the appliance.
timely and accurate diagnosis of relay or overload failure is crucial as symptoms such as intermittent cooling, repeated clicking, humming without startor complete compressor inactivity can indicate a malfunctioning start kit. Proper testing and verification-using manufacturer guidance, appropriate toolsand safety precautions-help avoid needless part replacement and ensure the true cause of the fault is addressed. When replacement is required, using the correct 4387535 kit and following recommended installation procedures restores reliable operation and minimizes the risk of further compressor damage.
the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit is a small but essential component for compressor protection and dependable refrigerator performance. Careful diagnosis, correct part selectionand proper installation-performed by a qualified technician when needed-preserve appliance efficiency and reduce the likelihood of costly repairs down the line.
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