4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit is a combined start-relay and thermal overload assembly designed for single-phase hermetic refrigerator compressors. The component houses the switching element that temporarily applies current to the compressor’s start winding (or otherwise alters starting characteristics) and an overload protector that interrupts power when motor current or temperature exceeds safe limits. It is a compact electromechanical/electronic device typically mounted on or near the compressor terminal block and specified by part number for compatibility with a range of Whirlpool domestic refrigeration models.
Inside the appliance, the relay and overload kit interfaces directly with the compressor motor terminals, the appliance control circuit (thermostat or main control board), and the incoming mains supply. During a start event the relay provides the additional torque or altered circuit path necessary for the compressor to accelerate to running speed; the overload element monitors current/heat and opens the circuit to prevent winding damage when stress conditions occur. Because it is part of the sealed-system drive chain, its operation affects compressor starting behavior, running stability, and overall cooling performance, and it is therefore a common point of failure when a refrigerator exhibits hard-start or no-start symptoms.
This article will describe the kit’s functional role in the motor starting sequence, outline typical compatibility and mounting considerations, and identify common failure symptoms such as humming without start, repeated clicking, tripped breakers, or thermal cutouts. It will present practical diagnostic approaches useful to technicians and informed owners – visual inspection, continuity and resistance checks, voltage measurements under start conditions, and substitution testing - along with safe troubleshooting practices and guidance on selecting and installing a correct replacement (matching electrical ratings, terminal configuration, and mounting method).
Table of Contents
- Function and Role of the Start Relay and Overload in Compressor Protection and Start‑Up Control
- How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Works Inside the Appliance
- Common Failure Symptoms and Measurable Electrical Signatures of a Defective Relay/Overload
- Compatibility, replacement Considerations, Installation Procedures, and Troubleshooting Diagnostics for the 4387535 Whirlpool refrigerator Compressor Relay And Overload Start Kit
- Q&A
- The Conclusion
Function and Role of the Start Relay and Overload in Compressor Protection and Start‑Up Control
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines a start relay and a thermal overload into a single service assembly to manage compressor start-up and protect the hermetic motor from electrical and thermal stress.The start relay momentarily connects the compressor’s start winding to create initial torque; as rotor speed approaches operating RPM the relay drops out and the compressor continues on the run winding. The overload is a temperature/current‑sensitive protector placed in series with the compressor circuit that opens under sustained high current or excessive winding temperature, preventing insulation breakdown and catastrophic motor damage.
Technically, failure modes of the relay and overload are distinct and identifiable during diagnosis: a defective relay typically causes persistent humming, repeated start attempts, or clicking as it energizes and de‑energizes, while a failed overload often measures as an open circuit at ambient temperature or allows starting current to fall outside expected ranges. fit and terminal compatibility matter - the kit must match the compressor’s terminal layout and any external start capacitor arrangements – so technicians verify part fit and wiring before installation. For practical troubleshooting, check continuity across the overload, monitor voltage on the start terminal only during initial energization, and compare measured inrush/current signatures against manufacturer service values; replace the relay and overload as a matched kit if either component shows degradation to restore reliable start behavior.
- Common symptoms: humming, repeated click-starts, no start, high inrush current, or open-circuit on ohm test
- Service actions: verify terminal labeling, measure continuity, observe start‑terminal voltage during startup
| Item | Description |
|---|---|
| Start relay | Temporary connection to the start winding during initial energization to develop torque |
| Overload | Series thermal/current protector that opens under sustained overload or overheating |
| Compatibility | Direct-fit for specified whirlpool compressors; confirm terminal layout and mounting 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 a start relay and a thermal overload protector into a compact module that mounts at the compressor terminals. The relay provides the temporary connection to the compressor’s start winding during initial energization, allowing the motor to develop sufficient torque; once the compressor reaches near-run speed the relay opens and the motor continues on the run winding. The overload element sits in series with the compressor motor and interrupts power when it senses excessive current or temperature rise, preventing winding damage. Technicians should verify terminal arrangement, voltage ratings, and physical mounting for compatibility with the compressor model before installing the kit, since correct wiring and thermal characteristics determine reliable starting behavior.
- Common failure symptoms: persistent humming without start, repeated click cycles, high line amperage when starting, or a relay that becomes unusually hot.
- Functional features: momentary start engagement,thermal cutout in series with the motor,and a compact plug-in form factor for specific Whirlpool compressors.
- Practical context: replacing the module typically remedies hard-start symptoms when the compressor itself is otherwise healthy; a locked rotor or internal compressor fault requires different service.
During a normal start sequence the relay closes only for a fraction of a second to route current through the start winding or capacitor network (depending on compressor design); after the motor accelerates the relay opens and the motor runs on the main winding. The overload is usually a temperature-sensitive device or bi-metal element that opens if sustained high current causes heating, and it will typically reset only after cooling. Fault modes to watch for include a relay that sticks closed (which risks overheating the start winding) or an overload that opens intermittently (leading to nuisance trips). For diagnostics, measure winding continuity and observe starting current with a clamp meter, and compare behavior to expected inrush profiles for the compressor; always isolate line power before swapping the 4387535 module or probing terminals.
| Item | Description |
|---|---|
| Start terminal | Connects to the compressor start winding during the brief start interval. |
| Run/common terminal | Continuous connection for the main run winding and line return. |
| Overload element | Series thermal protector that opens on sustained overcurrent/overtemperature. |
Common Failure Symptoms and Measurable Electrical Signatures of a Defective Relay/Overload
the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit combines the start relay that momentarily engages the compressor’s start winding with an overload protector that opens on excessive current or temperature. When either element begins to fail, the compressor may produce characteristic symptoms: a persistent humming noise without rotation, rapid on/off cycling, delayed starts, or a warm evaporator due to failure to reach operating pressure. These behaviors stem from the start circuit not supplying the start winding with the required short-duration torque boost or the overload opening under nominal start load; technicians should verify the kit is compatible with the compressor type and wiring on the specific Whirlpool model before replacing components.
defective relays/overloads show measurable electrical signatures that allow diagnosis with a multimeter and a clamp ammeter.Common signatures include an open-circuit overload (infinite resistance) when cold, unusually high resistance in an electromechanical relay coil, or absence of the expected start-circuit voltage pulse and reduced locked-rotor/inrush current at the compressor during attempted starts. For current-sensing or PTC-type relays, look for lack of the brief connection to the start terminal during cranking; for overload devices, a simple cold continuity check should read near zero ohms and open when tripped. Use targeted measurements-resistance across the overload, coil or relay terminals, applied voltage to the compressor’s start pin during a start attempt, and clamp-meter inrush readings-to distinguish a relay/overload fault from a bad compressor or start capacitor.
- Visual and thermal inspection for burn marks or melted terminals.
- Continuity check across the overload (should be closed when cold).
- resistance measurement of relay coil or relay contacts (compare to spec sheet or known-good unit).
- Measure voltage at the compressor start terminal during a start attempt and compare clamp-meter inrush to expected range.
| Item | Description |
|---|---|
| Overload continuity | Cold unit: closed/near-zero ohms; open or infinite resistance indicates failure. |
| Electromechanical relay coil | Typical order of magnitude: tens to low hundreds of ohms (varies by design); large deviations suggest internal fault. |
| Start-circuit voltage / inrush | During crank the start terminal should see a brief voltage and the compressor should draw a pronounced inrush current (commonly a few to several tens of amps on domestic units); absence indicates relay not engaging start winding. |
Compatibility, Replacement Considerations, Installation Procedures, and Troubleshooting Diagnostics for the 4387535 Whirlpool Refrigerator Compressor relay And Overload Start Kit
the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit is a combined start relay and thermal overload protector designed to engage the compressor start winding briefly and to open the circuit if the motor draws excessive current or overheats. Functionally, the relay provides the initial inrush path or switching action required to bring the compressor to operating speed, while the overload senses sustained overcurrent/overtemperature and interrupts the run circuit to protect the hermetic motor. Compatibility depends on the compressor terminal arrangement (typically three terminals labelled S, R, C), electrical ratings (line voltage, current capacity), and physical mounting; replacement requires matching terminal layout and thermal trip characteristics rather than only matching enclosure shape. Some compressors use solid-state start devices or a separate start capacitor, so verify the compressor type and wiring diagram before substituting this kit.
Installation and diagnostics follow standard appliance-electrical procedures: remove mains power, document and photograph wiring and mounting, swap the kit while preserving terminal orientation, then verify operation under load and measure running current with a clamp meter. Common service symptoms that point to a failing relay/overload include a humming compressor that won’t start, repeated clicking as the thermal protector cycles open, or an open overload on a continuity check. For troubleshooting,use a multimeter to check continuity through the overload (should close at ambient,open if tripped) and to verify there is no short to ground; use a clamp meter to compare running and locked-rotor currents to the compressor’s nameplate. Replace the kit if terminals are corroded, the thermal element shows no continuity, or measured currents exceed specified limits and the relay fails to engage consistently.
- Disconnect power and confirm zero voltage before testing or handling compressor terminals.
- Symptom: humming/no-start - check relay clicking, overload continuity, and compressor amp draw.
- Symptom: intermittent start – inspect relay contacts,terminal corrosion,and wiring harness integrity.
| Item | Description |
|---|---|
| Terminal convention | S, R, C (Start, Run, Common) – confirm labeling on compressor before replacement |
| Tools for diagnostics | Multimeter (continuity/ohms), clamp meter for running/starting current, basic hand tools |
| Acceptance checks | Overload shows continuity at ambient, relay engages during start, running current within nameplate limits |
Q&A
What is the 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit and what does it do?
This kit contains a start relay and an overload (thermal protector) that work together to help the compressor motor start and to protect it from overheating or excessive current. The relay provides the extra starting torque by briefly energizing the compressor’s start winding; the overload interrupts power if the compressor draws too much current or gets too hot.
What are the common symptoms of a failing start kit?
Typical symptoms include the compressor humming or clicking but not starting, the refrigerator not cooling, frequent start-stop cycling, a tripped breaker or blown fuse when the fridge tries to start, and sometimes a burning smell or visible scorch marks on the relay/overload assembly.
How can I test the relay and overload to see if thay are bad?
First disconnect power. Visually inspect for burn marks or a swollen/broken housing. For more reliable testing use a multimeter: the thermal overload should show continuity at room temperature (normally closed), and the relay/start device should show continuity or a characteristic low resistance between appropriate terminals (consult wiring diagram).A speedy screening method is to remove the relay and try to start the compressor briefly (only if you know what you’re doing) - if the compressor runs reliably with a known-good relay, the original relay is bad. If you’re unsure, have a trained technician perform the tests.
Can I replace the 4387535 start kit myself?
Yes, many owners can replace it themselves if they are comfortable working safely around appliances. Always unplug the refrigerator first, remove the compressor access panel, note terminal positions, unplug or unbolt the old kit, and mount/install the new kit in the same orientation. If you are uncomfortable with electrical work, or if removal requires refrigerant-system access, call an appliance technician.
Will replacing this part fix a compressor that won’t start?
Sometimes – if the problem is a failed relay or overload that prevents the compressor from starting, replacing the kit will restore operation. Though,if the compressor has an internal mechanical failure (locked rotor),a sealed-system issue (low refrigerant,leak),or an electrical/control board fault,replacing the start kit will not fix the underlying problem and further diagnosis is required.
how do I make sure I order the correct replacement part?
Match the part number (4387535) and verify compatibility with your refrigerator model number. Also confirm terminal layout, mounting style, and voltage rating match the original. Buying OEM or a direct-fit replacement from a reputable vendor reduces the risk of incompatibility.
How long should a start relay and overload kit last, and is there a warranty?
lifespan varies with usage and operating conditions; many kits last several years but can fail sooner if the compressor struggles or the fridge operates under high ambient heat. Warranty length depends on the seller or manufacturer – check the part listing or your retailer for specific warranty and return policies.
What safety precautions should I take when handling or installing this start kit?
Always disconnect power before working on the refrigerator. Avoid shorting terminals, and don’t attempt sealed-system repairs or refrigerant work yourself. Use correct tools, note wiring to ensure proper reconnection, and if you encounter soldered, corroded, or hard-to-remove components or if the compressor still won’t start after replacement, call a qualified appliance technician.
The Conclusion
The 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit plays a focused but critical role in refrigerator operation by supplying the initial electrical boost to start the compressor and by protecting the motor from overheating and electrical overload. Proper function of the relay and overload device helps ensure reliable compressor starts, consistent cooling performance, and protection against damage that can lead to more extensive and costly failures.
Because symptoms of start-kit failure (intermittent cooling,repeated clicking,or a non‑starting compressor) can overlap with other appliance issues,accurate diagnosis is vital before replacing components. Testing and inspection-ideally performed by a qualified technician-allow the failing relay or overload to be identified with confidence. When replacement is required, using the correct kit for the model and following manufacturer guidance helps restore performance and reduces the risk of recurrent faults.
attention to the relay and overload start kit as part of routine troubleshooting and maintenance contributes to greater appliance reliability, safety, and lifecycle value. Timely, properly performed diagnosis and replacement protect the compressor and support efficient operation of the refrigerator.
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
The Blincoo Elite 48" Heavy Duty Dog Rope Toy is made for large breeds that love tug-of-war, chewing, and active play. Strong, simple, and fun for powerful dogs.
Shop on TikTok