4387535 Whirlpool Refrigerator Compressor Relay And Overload Start kit is a combined start-relay and thermal overload device used to start and protect a refrigerator compressor motor. The kit typically contains an electromechanical or solid-state start switching element paired with an overload protector; it is indeed designed to be mounted on or adjacent to the compressor and wired into the compressor’s start/run circuit.
Within the appliance the part serves two complementary roles: it provides the temporary additional current or change in circuit needed to engage the compressor’s start winding or start mechanism during motor spin-up, and it opens the circuit when the compressor draws excessive current or reaches a hazardous temperature. It directly interfaces with the compressor windings, incoming line voltage, and the refrigerator’s control/thermostat or electronic control board, and its correct operation is critical as the compressor is the primary device that circulates refrigerant and maintains the cooling cycle.
This article explains the kit’s functional principles, typical applications and compatibility considerations with single‑phase hermetic compressors, common failure symptoms (for example humming, rapid cycling, failure to start, or tripped breakers), and practical troubleshooting steps a technician or learned appliance owner can use to isolate a start-relay/overload fault. It also covers replacement considerations such as verifying part number and electrical ratings,proper mounting and wiring,and basic verification after replacement so readers can make informed diagnostic and repair decisions without unnecessary component swaps.
table of Contents
- Function and Role of the Compressor Relay and overload Start Kit in Whirlpool Refrigeration Systems
- How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit works Inside the Appliance
- Common Failure Symptoms and Diagnostic Measurements for a Faulty Relay and Overload Start Kit
- Compatibility,Model Fitment and replacement Considerations for the 4387535 Relay and Overload Start Kit
- Q&A
- In Conclusion
function and Role of the compressor Relay and Overload Start Kit in Whirlpool Refrigeration Systems
the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit performs two coordinated functions: the start relay momentarily connects the compressor’s start winding to provide the torque needed to spin a stationary motor,while the thermal overload interrupts power if the motor draws excessive current or overheats. In practice the relay may be a PTC-type device or a mechanical/current-sensing relay that drops out after the motor reaches running speed; the overload is a temperature- or current-responsive protector that resets manually or automatically depending on its design. Correct operation of both elements ensures the hermetic compressor will start reliably and that a locked rotor or excessive load does not cause motor damage or wiring overheating.
Technicians evaluate this kit by observing start behavior and measuring continuity and resistance across relevant terminals,but visual signs and operational symptoms are often the fastest indicators of failure; replace the kit with the correct part number to match terminal layout and nominal line voltage,and always disconnect mains before testing. Typical failure modes include a relay that clicks without spinning the compressor and an overload that opens after repeated start attempts; correct selection ensures mechanical and electrical compatibility with the compressor motor and harness,restoring proper start torque and overcurrent protection without modifying the system.
- Common symptoms: rapid clicking, compressor hum without rotation, intermittent starts, or visible heat/corrosion on terminals.
| Item | Description |
|---|---|
| Relay | Provides brief connection to the compressor start winding to develop initial torque (mechanical or PTC types). |
| Overload | Thermal/current protector that opens the compressor circuit under sustained overcurrent or overheating conditions. |
| Typical rating | Matched to appliance line voltage and compressor design (e.g., nominal 115-120 V systems in many Whirlpool units). |
| Compatibility | Designed for single-phase hermetic refrigeration compressors; confirm terminal arrangement and electrical ratings before replacement. |
How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Works Inside the Appliance
The 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit combines the start-relay function and a thermal overload protector to manage the compressor’s startup and protect its motor during operation. The relay momentarily applies current to the compressor’s start winding to produce the higher torque required to overcome initial motor inertia; once the compressor reaches near-run speed the relay removes the start winding from the circuit and the motor continues on the run winding. The overload device is a temperature- or current-sensitive protector mounted at the compressor terminal assembly that opens the supply to prevent damage from sustained high current or overheating, and then restores operation after the protector cools or the fault is cleared. This kit installs on the three-terminal cluster commonly labeled S, R, C and is intended as a matched replacement for compressors with that configuration.
From a diagnostic and compatibility standpoint,the relay and overload act as a coordinated pair: failed start relay behavior typically appears as loud humming with no rotation or rapid on/off cycling,while overload trips show as intermittent operation or a complete loss of compressor function after the unit runs briefly. Technicians confirm function with a clamp meter to observe inrush current during attempted starts and with an ohmmeter to check continuity across terminals; expected behavior is a brief high inrush that drops to steady run current once the relay disengages. Select a replacement kit rated for the appliance’s line voltage and compressor amp draw; improper matching can mask compressor faults or allow thermal stress. Practical examples include replacing the kit when a unit hums but does not pump refrigerant, or when the compressor repeatedly overload-trips after brief operation.
- Symptoms: humming at startup, repeated clicking, intermittent cooling, or compressor hot to touch.
- Features: momentary start torque support,thermal overload protection,fits three-terminal compressors.
- Diagnostics: measure inrush current and continuity between S, R, and C terminals before replacement.
| Item | Description |
|---|---|
| Start Relay | Provides temporary current to the start winding to achieve compressor startup torque. |
| Overload Protector | Opens the compressor supply when temperature/current exceed safe limits to prevent motor damage. |
| Compatibility / Terminals | Designed for three-terminal (S, R, C) hermetic compressors; match voltage and ampere ratings to the compressor. |
Common Failure Symptoms and Diagnostic Measurements for a Faulty Relay and Overload Start Kit
the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines the start relay and thermal overload protector used to engage the compressor start winding and to protect the motor from locked-rotor or sustained overcurrent conditions. when this kit begins to fail, typical behavior includes repeated clicking from the compressor area, the compressor humming without achieving rotation, rapid cycling on the thermostat, or the circuit breaker/trip protector opening under high inrush conditions. These symptoms occur because the relay fails to properly deliver the momentary start voltage to the start winding or because the overload opens intermittently under normal load, so the compressor never reaches normal running speed or draws excessive current while attempting to start.
- Clicking or humming at compressor: measure voltage at compressor terminals during a start attempt; absence of a brief start-voltage pulse to the start terminal indicates the relay isn’t switching.
- Compressor will not start but has continuity to common/run: use a clamp ammeter - excessively high or repeated inrush current suggests the start function is not engaging and the motor is stalling.
- Open overload on cold bench test: with power removed, check overload for continuity; an open circuit where continuity is expected indicates a tripped or failed overload protector.
- Intermittent operation: compare measured values to a known-good relay or the OEM specification, as some solid-state relays present non-intuitive resistance readings on an ohmmeter.
Safety: disconnect mains power before performing resistance or continuity checks.For diagnostics, use a multimeter to verify continuity across the overload and to confirm a brief voltage pulse appears at the start terminal during a powered start attempt; use a clamp meter to compare start inrush against normal running current.if the start terminal never receives a pulse while the compressor common has mains present, the 4387535 start kit or its wiring is the likely fault; if the overload shows open continuity at ambient temperature, replace the overload. The table below summarizes the practical checks technicians typically use.
| Item | Description |
|---|---|
| Continuity (overload) | Should read continuity (low ohms) at ambient; open/infinite indicates failed/tripped overload. |
| Voltage at start terminal | During start attempt a brief mains-equivalent pulse should appear; absence indicates relay not connecting. |
| Start relay resistance | Many mechanical relays show low resistance when engaged; solid‑state devices can show high/variable readings-compare to spec or good unit. |
| Inrush/current draw | Start current should be several times running current only briefly; sustained high or stalled readings indicate start circuit failure. |
Compatibility, Model Fitment and Replacement Considerations for the 4387535 Relay and Overload Start Kit
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines a start relay and a thermal/overload protector to coordinate compressor starting and protect the motor during abnormal conditions. the relay provides a timed or PTC-driven connection to the compressor’s start winding to develop initial torque, then opens to leave the run winding energized; the overload element interrupts the circuit if the compressor draws excessive current or reaches a high temperature. Technically, compatibility depends on matching the compressor’s terminal layout (common, start, run), the nominal operating voltage, and the physical mounting so the overload senses heat from the compressor body as intended.Replacing a factory relay with this kit is acceptable only after verifying these electrical and mechanical interfaces and confirming that the relay’s start characteristics suit the compressor’s locked-rotor and running current profile.
Practical replacement decisions require inspection and simple electrical tests: measure continuity between terminals, check for short to ground, inspect for burned contacts, and confirm that the relay opens after the start interval if it’s a timed device. Technicians should also verify OEM cross-reference numbers and model fitment lists for the appliance model; mismatched kits can allow a compressor to run with insufficient starting torque or fail to trip on overload, which risks motor damage. For field repair, document the refrigerator model and compressor part number, confirm terminal identification, and mount the overload so its thermal behavior matches the original installation to preserve intended protective response.
- Common indicators for replacement: compressor hums but does not start, repeated clicking, or open/short on relay terminals during resistance checks.
- Fit checks: terminal count and arrangement, rated voltage/current, and mounting clip or screw pattern.
- Testing tips: use a multimeter to confirm continuity and compare measured resistance to expected start-run values.
| Item | Description |
|---|---|
| Terminal configuration | Three spade terminals labeled common,start,run; must match the compressor harness and wiring diagram. |
Q&A
What is the 4387535 Whirlpool refrigerator Compressor Relay and Overload Start Kit and what does it do?
the 4387535 start kit is a combined compressor start relay and thermal overload protector used on many Whirlpool-family refrigerators. The relay provides a brief boost to engage the compressor’s start winding when the compressor first comes on; the overload protects the compressor motor from overheating and excessive current by opening the circuit if the motor gets too hot. Together they help the compressor start reliably and protect it from damage.
What are the common symptoms of a failing relay/overload kit?
Typical signs include: the refrigerator runs but does not cool, a loud humming or clicking noise from the compressor area, the compressor trying to start repeatedly (short start cycles), the compressor being hot to the touch, or the refrigerator refusing to start at all. These symptoms can indicate a bad start device or an electrical problem in the compressor circuit.
How can I safely test the 4387535 relay and overload to see if they are bad?
Always disconnect power before testing. Remove the kit from the compressor to access terminals. Use a multimeter to check for continuity on the overload (it should typically show continuity at room temperature). For the relay, check for continuity between the common and start/run terminals per the component markings-many relays will show measurable resistance; if you see an open circuit where you expect continuity, the part is likely bad. A common simple check is to listen for a rattle when gently shaking the relay (loose guts indicate failure). If uncertain, replace the kit or consult a technician-avoid powering a suspected-faulty relay on the compressor for extended periods as that can damage the compressor.
How do I replace the 4387535 start kit? What safety precautions and tools are needed?
Basic steps: unplug the refrigerator; access the compressor at the back or under the appliance; remove any protective cover; disconnect the wiring and remove the old relay/overload assembly (note wire positions or take a photo); fit the new kit in the same orientation and reconnect wires; replace the cover and restore power. Tools: nut driver or socket set, pliers, and a multimeter if testing. Safety: always disconnect mains power before working on the appliance, avoid bending or damaging the compressor terminals, and do not attempt sealed-system repairs (refrigerant) – call a licensed technician for compressor or refrigerant work.
How do I know if the 4387535 kit is compatible with my refrigerator?
Check your refrigerator model number and consult the manufacturer parts list or a trusted parts distributor. The 4387535 kit is used on many Whirlpool, KitchenAid, maytag and Amana models, but compatibility varies by model and production date. The safest method is to search the model number on the OEM parts site or provide the model number to the parts supplier to confirm fitment.
Can I run the refrigerator temporarily with a bad relay/overload while waiting for a replacement?
No-running the refrigerator with a suspected faulty relay or overload is not recommended. A bad relay may prevent the compressor from starting or cause hard starting that overheats and damages the compressor; a faulty overload may fail to protect the compressor from overheating. If the compressor will not start, unplug the unit and replace the start kit before further operation.
Should I buy the OEM 4387535 or is an aftermarket equivalent acceptable?
OEM parts are recommended because they are specified by the manufacturer for proper fit and function. Many aftermarket start kits are available and can be reliable if they match electrical specifications and terminal arrangements. When buying aftermarket,choose a reputable supplier and ensure the kit is designed for your compressor type. Avoid bargain parts of unknown origin-incorrect start devices can cause compressor damage.
If replacing the 4387535 kit doesn’t fix the problem, what should I check next?
If a new start kit does not restore compressor operation, possible causes include a locked or mechanically failed compressor (seized), a failed start or run winding inside the compressor, a problem in the control board or wiring, or a sealed-system refrigerant issue. At that point you should measure compressor terminal resistances, check continuity to the evaporator fan and defrost components, and likely call a certified appliance technician for sealed-system diagnosis and repair. Do not attempt refrigerant repairs yourself-those require certified technicians and specialized equipment.
In Conclusion
The 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit plays a key role in the reliable operation of the refrigeration system.the relay facilitates the initial engagement of the compressor’s start winding while the overload device protects the compressor from excessive current and overheating. Together these components help ensure consistent starting performance, reduce mechanical and electrical stress on the compressor, and contribute to the overall cooling reliability of the appliance.
Accurate diagnosis is vital before replacing the start kit. Symptoms such as repeated clicking, a compressor that hums but does not run, intermittent cooling, or frequent tripping of circuit protection can indicate a faulty relay or overload, but similar symptoms may be caused by other issues (for example, a failed compressor motor or sealed-system problems). Proper testing with appropriate tools or evaluation by a qualified technician helps confirm the root cause and avoids unnecessary part changes.
When diagnosis indicates the relay and overload are defective, timely replacement with the correct part can be a cost-effective way to restore normal operation and help prevent further compressor damage. Installation should follow safety procedures and manufacturer guidance; if there is any uncertainty, having the work performed by a trained service professional is advisable. the 4387535 start kit is an important, serviceable component whose correct diagnosis and replacement can support long-term appliance performance and reliability.
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