4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit is a combined starter device and protective thermal overload designed for single‑phase hermetic refrigeration compressors. As a start kit, it typically contains the start relay (which might potentially be a PTC or electromechanical type) and an overload protector (a temperature- or current‑sensitive cutout) packaged for direct mounting on the compressor housing or in the compressor terminal housing.
Within the refrigerator’s sealed‑system electrical circuit the start kit’s relay provides the transient change in circuit conditions required to energize the compressor’s start winding and produce sufficient starting torque, while the overload element disconnects power to the compressor if the motor overheats or draws excessive current. The component interfaces directly with the compressor motor terminals and indirectly with the thermostat/controls and the line supply; its proper operation affects compressor start performance, run stability, and protection against locked‑rotor and thermal fault conditions.
In this article readers will find a technical explanation of how the 4387535 start kit functions, guidance on electrical and mechanical compatibility with common Whirlpool compressor models, typical failure symptoms (for example humming without rotation, repeated click‑trips, or no run condition), diagnostic approaches a technician can use, and practical replacement considerations such as matching terminal configuration, ratings, mounting method, and safe isolation procedures before service. The aim is to give technicians, engineers, and informed appliance owners the context needed to diagnose, verify compatibility, and replace the part when necessary.
Table of Contents
- Functional Role of the Compressor Relay and Overload Start Kit in the Refrigerator’s Electrical and Mechanical Systems
- How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Operates Within the Compressor Start and Overload Protection Circuit
- Diagnostic Symptoms and Common Failure Modes of the Compressor Relay and Overload Start Kit
- Replacement Considerations,Installation Procedure,and Model Compatibility for the Compressor Relay and Overload Start Kit
- Q&A
- In Retrospect
Functional Role of the Compressor Relay and Overload Start Kit in the Refrigerator’s Electrical and Mechanical Systems
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines a thermostatic thermal-overload protector and an electromechanical/solid-state start relay to manage compressor starting and short-term protection. The relay delivers the extra starting torque by momentarily routing current to the compressor’s start winding (or switching a start capacitor circuit), while the overload is a series thermal device that opens the circuit if the compressor draws excessive current or overheats. In practice this means the relay produces a characteristic click when the thermostat calls for cooling and the compressor should spin up; if the relay or overload fails you will typically see a steady hum, a no-start condition, or repeated attempts to start until the overload opens.
- Typical terminals: C, S, R – confirm mapping before replacement.
- Failure symptoms: humming without run, rapid cycling, or open-circuit continuity on the overload.
- Compatibility check: match voltage, compressor model family, and terminal layout rather than chassis or trim model alone.
| Item | Description |
|---|---|
| Relay function | Provides momentary connection to start winding or start capacitor to achieve sufficient torque for compressor startup. |
| Overload function | Thermal protector in series with the compressor that opens under overcurrent/overtemperature to prevent winding damage. |
| Common diagnostics | Measure continuity across overload and verify relay switching under applied voltage; observe mechanical click and compressor current draw. |
When replacing or testing the kit, disconnect mains power and verify terminal labeling; the correct replacement must match the compressor’s electrical characteristics (voltage, locked-rotor current) and terminal configuration. For field troubleshooting, use a clamp ammeter and an ohmmeter: a healthy start event shows a short-duration peak in current as the relay engages and the compressor accelerates to run current, while the overload should present low resistance at room temperature and become open if it has tripped or failed. Proper installation requires secure mounting to the compressor or bracket,correct wiring to the Common/Start/Run terminals,and avoiding exposure to refrigerant oil or moisture that can degrade the kit’s connectors.
how the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Operates Within the Compressor Start and Overload Protection Circuit
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload start Kit integrates a start relay and a thermal overload protector into a compact assembly that interfaces directly with the compressor’s electrical terminals. During a normal start cycle the relay momentarily energizes the compressor’s start winding to produce the extra torque required to bring the motor up to speed; once the rotor approaches run speed the relay drops out and the motor continues on the run winding alone. The overload element is a temperature- or current-sensitive device mounted against the compressor shell that opens the circuit if the compressor draws excessive current or the shell temperature rises beyond safe limits, preventing damage from repeated stall or locked-rotor conditions. Proper function depends on correct terminal alignment and electrical characteristics that match the compressor’s design, so the 4387535 kit must be used on compatible Whirlpool compressors or verified cross-referenced models to maintain correct start timing and protection thresholds.
Technically, failures of either the relay or overload produce distinct symptoms and require different diagnostic approaches: a faulty relay commonly causes a humming compressor that will not start, while a tripped or open overload produces an open circuit and no continuity to the compressor. Technicians verify operation by measuring continuity thru the overload, confirming the relay switches the start winding only during the inrush event, and observing line voltage behavior at the compressor during a start attempt. Practical replacements involve matching the kit’s terminal layout and electrical ratings to the compressor; swapping in a correctly specified 4387535 restores proper start assist and overcurrent protection, whereas an incorrectly specified kit can allow excessive inrush or fail to protect the motor. For safe troubleshooting, always disconnect mains power before measuring or replacing the relay/overload assembly and follow manufacturer service procedures.
- Common symptoms: compressor hums without starting, intermittent starts, or no continuity to compressor.
- Key checks: continuity through overload, presence of momentary start circuit during startup, visual signs of heat or burn at terminals.
- compatibility: match part number, terminal configuration, and voltage ratings to the compressor model.
| Item | Description |
|---|---|
| Function | Start assist (relay) plus thermal/current-based overload protection |
| Typical location | Mounted to compressor shell or chassis near compressor terminals |
| Diagnostics | Continuity checks, start-circuit switching observation, swap with known-good unit |
| Compatibility note | Must match compressor terminal layout and electrical ratings; use exact part or approved cross-reference |
Diagnostic Symptoms and Common Failure Modes of the Compressor 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 control engagement of the compressor’s start winding and to interrupt power if the compressor draws excessive current or overheats. The relay provides a timed, high-inrush path to the start winding and then drops out once the compressor reaches running speed; the overload is a series thermal device that opens the circuit when the motor temperature or sustained current exceed its threshold. When assessing compatibility and behavior, technicians should inspect coil resistance, contact actuation characteristics, and trip thresholds against the compressor motor’s requirements and manufacturer cross-reference data rather than assuming universal interchangeability.
Diagnostic signs point to specific failure modes and can be reproduced with simple measurements and observation: repeated rapid clicks at power-up commonly indicate relay contact failure or an open start element, continuous humming with no turnover suggests the start circuit is not engaging, and frequent thermal trips or long run-times point toward overload drift or excessive motor load.Practical troubleshooting steps include measuring relay coil continuity and resistance, checking for momentary contact closure during start, and comparing measured inrush/current draw to expected values; these checks help separate a failed kit from motor winding faults or external causes such as low refrigerant. Typical observable symptoms and fast interpretations are listed below.
- No start with clicking: Relay attempts to engage but contacts are worn or the start path is open; verify continuity and contact behavior.
- Humming, no turnover: Start winding not energized long enough or start relay stuck; check relay timing and start winding resistance.
- Intermittent starts/cycling: Relay or overload with marginal contacts/thermal drift; reproduce under load and monitor temperature response.
- Runs then trips or runs hot: Overload opening under normal load suggests overload degradation or excessive compressor current; measure operating amperage.
| Item | Description |
|---|---|
| Relay continuity | Low resistance on coil indicates intact relay; open coil = failed relay. |
| Overload response | Opens at elevated temperature/current-verify by controlled warm-up or amp measurement. |
replacement Considerations,Installation Procedure,and Model Compatibility for the compressor Relay and Overload start Kit
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines a start relay and a thermal overload protector that together manage the compressor’s start sequence and protect the motor from stall or sustained overcurrent. The relay momentarily routes current to the compressor’s start winding to produce the necessary torque,while the overload opens the circuit if the motor draws excessive current or overheats. Replacement considerations include matching the kit’s terminal arrangement and physical mounting to the compressor pins, confirming the rated operating voltage (typically 120 VAC for North American units), and ensuring the overload’s trip characteristics are compatible with the compressor locked-rotor current. For troubleshooting, a compressor that clicks but does not run or one that draws excessive current at startup often indicates a failed relay or overload; technicians should verify continuity and compare start/run winding resistance to manufacturer specifications before replacing components. Disconnect mains power and document wire positions before removal to avoid cross-wiring on reinstall.
- Power off and verify zero voltage at the outlet.
- Remove the old module and inspect compressor pin layout and mounting clip.
- Install the new unit with correct terminal connections (Common, Start, Run) and secure mounting.
- Restore power and observe compressor start current and normal run sound for a full start cycle.
Model compatibility requires matching both electrical and mechanical interfaces: confirm the service part number on the old kit or cross-reference appliance model numbers with Whirlpool parts literature to ensure fit. some replacement kits are universal in function but differ in physical clip design or overload trip point; using a mismatched overload can produce nuisance trips or fail to protect the compressor. For practical context, swapping in the 4387535 kit on a unit with matching terminal spacing and clip attachment will typically restore correct start behavior, whereas forcing an incorrect-style module can leave the compressor vulnerable.After installation, measure steady-state run current and monitor temperature rise during the first few hours of operation to verify the kit is functioning as intended.
| Item | Description |
|---|---|
| Part | 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit |
| Function | Provides start assist and thermal/overcurrent protection for single‑phase compressors |
| Typical supply | 120 VAC (North American refrigerators) |
| Compatibility check | match compressor pin spacing, mounting clip, and overload trip characteristics |
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 relay and overload protector assembly for the compressor on many Whirlpool-family refrigerators. The start relay momentarily routes power to the compressor’s start winding to get it running, while the overload protector opens the circuit to the compressor if it overheats or draws excessive current. Together they allow safe and reliable compressor start-up and protect the compressor from electrical/thermal damage.
What symptoms indicate the relay/overload (part 4387535) is failing?
Common symptoms include: the fridge runs but does not cool,repeated clicking or buzzing from the compressor area,the compressor not starting while the light and fans run,the compressor getting unusually hot,or the compressor trying to start repeatedly and tripping the breaker. These symptoms are typical of a bad relay/overload,but the sealed refrigeration system and other components (capillary,start device,thermostat,control board) can also cause similar behavior,so verify before replacing parts.
How can I test whether the 4387535 relay/overload is bad?
Start with simple checks: unplug the refrigerator,remove the rear access panel,and inspect the relay for burn marks or a loose fit on the compressor terminals. A common quick check is the “shake” test-gently shake the removed relay; a rattling internal component can indicate failure. For more definitive testing, check continuity across the relay/overload terminals with a multimeter-an open circuit where continuity is expected indicates failure. As some relays are PTC/solid-state types, electrical tests can be limited; if in doubt, replacing the inexpensive relay/overload is frequently enough the fastest fix. Do not attempt high-voltage bench tests unless you are trained and equipped.
Is the 4387535 kit compatible with my refrigerator model?
Compatibility depends on the refrigerator model and compressor type. To confirm fitment, compare the part number (4387535) with the OEM part listed for your exact appliance model number (found on the fridge’s model/serial tag). You can check Whirlpool’s parts website or reputable parts distributors, or contact Whirlpool support. Do not assume interchangeability between different compressors or brands without verification.
Can I replace the 4387535 relay/overload myself, and what are the basic steps?
Yes-many appliance owners with basic mechanical skills can replace this kit. General steps: unplug the refrigerator, remove the rear access panel, disconnect and remove the old relay/overload from the compressor terminals (note orientation), fit the new relay/overload securely onto the compressor terminals, replace the access panel, and restore power. Always disconnect electrical power before working on the appliance. If you are uncomfortable working near the compressor or unsure about compatibility, hire a qualified technician.
What is the difference between the start relay and the overload protector?
The start relay provides a short-duration connection to the compressor’s start winding (or engages a start device) to get the compressor spinning. The overload protector is a thermal/electrical safety device that opens the compressor circuit if the motor overheats or draws too much current. The relay initiates starting; the overload protects the compressor during fault conditions. The 4387535 kit contains both components as a matched assembly.
Could a bad relay/overload damage the compressor, and will replacing it always fix cooling problems?
A faulty relay/overload can cause repeated failed start attempts or overheating, which, over time, can damage the compressor windings.Replacing a failed relay/overload frequently enough fixes starting and cooling problems if the compressor itself and the sealed system are intact. However, if the compressor has been damaged or there are other system faults (refrigerant leak, failed start capacitor or control board, seized compressor), replacing the relay/overload alone will not restore cooling. Proper diagnosis is crucial.
Where should I buy the 4387535 kit and is there any warranty or things to watch for?
Buy 4387535 from authorized Whirlpool parts dealers, major appliance parts retailers, or the manufacturer’s parts website to ensure you receive a genuine OEM part. Many retailers offer limited warranties-check the seller’s return and warranty policy before purchasing. Avoid unbranded or suspiciously cheap parts; lower-quality replacements may fail sooner and could risk compressor damage. If your refrigerator is still under manufacturer warranty, contact Whirlpool or an authorized service technician first.
In retrospect
The 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit plays a critical role in the operation and protection of a refrigerator’s compressor by providing the initial starting torque and guarding the motor against overheating and electrical stress. Properly functioning relay and overload components help ensure reliable compressor starts, contribute to steady cooling performance, and reduce the risk of premature compressor failure, making them an critically important element in overall appliance efficiency and longevity.
Accurate diagnosis and timely replacement of a faulty relay and overload kit are essential to avoid unnecessary component changes and to prevent more costly damage to the compressor. When symptoms or testing indicate a defective start device, replacing it with the correct 4387535 kit or an appropriate equivalent-following manufacturer guidelines and safety practices or consulting a qualified technician-helps restore dependable operation and protects the refrigerator’s long-term performance.
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