4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit âis âaâ combined start relay and overload protector designed for use on singleâphase hermetic ârefrigerator compressors. The âassembly typically contains the relay mechanism that engages the â˘compressor start winding and a thermal or currentâsensing overload device that opens the circuit âŁif the compressor draws excessive currentâ or overheats. As a discrete electromechanical âservice part, it mounts at or near the compressor terminal â˘block and is available as an OEM replacement for compatible Whirlpool âŁand similar domestic refrigeration models.
Inside the appliance the relay and â¤overload start kitâ sits in the compressor start circuit and directly interfaces with âthe compressor windings,the incoming line voltage,and the refrigerator’s control elements â(thermostat or electronic control board).â when the refrigerator demands cooling the relay provides a momentary connection to the start winding (or modifies startâcircuit resistance) to produce the high starting torque required to spin⣠the compressor motor; once running the â¤relay disconnects the start path. The overload protector is⢠a safety device that opens the compressor â¤supply under sustained overcurrent or thermal stress, preventing winding damage and reducing fire risk.â because the component operatesâ at line voltage and underâ thermal stress, its electrical ratings, terminal configurationand mounting orientation are importantâ for correct operation and reliable interactionâ with the rest of the refrigeration system.
This⣠article will describe the component’s function in detail,list common compatible applications and how to confirm part fitment,and summarize typical failure symptoms such as a compressor that humsâ but does not start,frequent tripping,excessiveâ inrush current,orâ visible heat damage â¤at terminals.Itâ will also outline practical troubleshooting steps a technician can use (visual inspection, terminal voltage checks, amp draw measurements, simple continuity and resistance checks,â and substitution âtesting) and provide replacement considerations including matching part number/terminal layout, verifying voltage and thermal trip characteristics, proper mountingandâ basic safety precautions whenâ working on lineâpowered refrigeration systems.
Table of Contents
- Function and Role of the Compressor âRelay and âOverload Start kit in Whirlpool Refrigeration Systems
- How theâ 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Interfaces with the⣠Compressor Motor and Start Circuit
- Diagnostic Symptoms of Relay or Overload Failure and Recommended Electricalâ Test Points
- Compatibility, Replacement Considerationsand Step-by-Step Installation Guidelines for Service Technicians
- Q&A
- Future outlook
Functionâ and Role of the Compressor Relay âand Overload â¤Start Kit in Whirlpool⣠Refrigeration Systems
The 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit integrates a start relay (or start device) with an overload protector to manageâ the high inrush current and protect the compressor â¤motor during and after start-up. The start element momentarily⤠connects the compressor’s⢠start winding (or provides an equivalent phase-shifted current) to generate necessary starting torque; the overload is a thermal/current-sensitive⤠device placed inâ series with the run winding to interruptâ power if the motor overheats or draws excessive current. In many Whirlpool installations this kit replaces a failed⢠relay or a separate start âcapacitor arrangement and is sized to match the⣠compressor’s rated âvoltage and starting current, âbut installers must confirm terminal âconfiguration and electrical âratings before substitution.
Behaviorally, a functional start kit produces a short,â high-torque âstart pulse andâ then drops out, while the⣠overload remains passive until abnormal conditions occur; a failing relay or⢠start device typically causes rapid clicking, long crank intervalsor a warm compressor that will not sustain rotation. Techniciansâ should verify terminal markings (such as S, M, C â on the compressor), measure coil continuityand check inrush/current draw with a clamp meter to differentiate a bad start kit from a â¤mechanically locked compressor orâ refrigerant restriction.⣠Typical practical checks: replace the kit when⤠the compressor struggles toâ start but shows ânormal locked-rotor current limits during bench testingand always confirm compatibility âwith the compressor model and wiring harness to avoid misapplication.
- Common symptoms: rapid relay clicking, compressor hum without rotation, warm compressor shell, intermittent starts.
- Installation checks:⣠confirm terminalâ labels,verify rated â˘voltage/current,secure mechanical⤠mounting for âthe overload,and confirm connector polarity.
- Diagnostic tools: clamp ammeter for inrush, multimeter⤠for continuity,â and temperature checks for overload activation.
| item | Description |
|---|---|
| Start relay / start device | Provides momentary connection or phase-shifted current⤠to the start winding to generateâ starting torque; may be electromechanical or solid-state. |
| Overload protector | Series thermal/currentâ protector that opens the circuit when the compressor overheats or exceeds âsafe current limits, preventing damage. |
How the 4387535 Whirlpool Refrigerator Compressor Relay And Overload Start Kit Interfaces with the Compressor Motor and Start Circuit
The 4387535 Whirlpool Refrigerator â¤Compressor Relay and Overload Start Kit provides theâ electrical interface between the refrigerator’s line voltage and the compressor motor’s start âand ârun windings. The relay elementâ momentarily connects the start winding to the supply during motor startup, either by⤠closing an internal contact or by changing its âŁimpedanceand⤠then removes that connection once⣠the ârotor reaches operating speed. Theâ overload component is a thermal/current-sensitive device wired in series with the âcompressor’s common terminal; it opens underâ sustained overcurrent or excessive temperature to protect the motor windings. Physically the kit mounts adjacent to the compressor⤠and uses the compressor’s standard⤠spade terminal cluster (commonly labeled C,â S, R) so itâ directly interfaces with those terminals without additional wiring in most compatible Whirlpool models.
in normal operation the relay reduces the time the⢠start winding sees high current, limitingâ locked-rotor currentâ and allowing the compressor to accelerate to synchronous speed; the overload prevents damage if the compressorâ seizes or draws excessiveâ current. Technicians diagnose relay/overload failures by measuring continuity across the start and run terminals duringâ a start attempt, monitoring inrush currentor observing symptoms such as rapid clicking, a humming compressor thatâ fails to runor repeated thermal trips. When replacing this âkit, match the terminal arrangement, mounting⢠styleand line-voltage rating (typically 115-120 VAC in household units)â to ensure compatibility; incorrect selection can result in poor starting performance or ineffective protection.
- Common failure symptoms: humming with no start, intermittent starts, intermittent thermal trips of the overload.
- Functional features: momentary start connection, seriesâ thermal/current âoverload protection, direct âspade-terminal interfaceâ to compressor.
- Practical check: compare âterminal labels and measure continuity/current during a controlled start attempt before replacement.
| Item | Description |
|---|---|
| Terminals | C (Common),⤠S ⢠(start), R (Run) – connects directly to compressor⢠spade cluster |
| Function | Relay provides transient start-winding supply;â overload opens â¤circuit under âsustained overcurrent/overtemperature |
| Voltage | Designedâ for household line voltage â(typically 115-120 VAC in North American models) |
Diagnostic symptoms âŁof Relay or overload Failureâ and Recommended Electrical⤠Test Points
The 4387535 Whirlpool Refrigerator⣠Compressor Relay And Overload Start Kit âŁcombines a start-assist device with⢠a thermal overload protector â¤to supply initial torque to the compressor motor and to open the circuit under sustained overcurrent⤠or overtemperature conditions. In operation the start element⤠appliesâ or allows currentâ to the compressor’sâ start winding only during the âbrief crank interval; the overload is in series with the common/run â˘circuit to protect the motor. Failures present as electrical or mechanical symptoms rather than gradual performance lossand correct replacement⢠requires matching âterminal layout and electrical characteristics to âthe compressor model you are servicing.
- Compressor hums but does not turn âandâ never draws a startup current spike.
- Compressor starts⤠intermittently or requires⤠several⣠attempts (long crank time).
- frequent tripping of the refrigerator circuit breaker or thermal protection.
- Visible discoloration, melted plastic, â¤or burning odor at the relay/overload location.
- Normal steady-state current but absent or reducedâ inrush current âat startup.
Forâ diagnostics, isolate mains power before performing continuity or resistance checksand perform live voltage/current measurements only with appropriate PPE and aâ clamp meter. With the compressor connected and the system attempting to start, âmeasure âvoltage between the compressor terminals:⤠supply voltage should appear at Common to Runand voltage to the Start terminal should⣠be present during âthe initial âcrank and fall away once⤠the motor is running; absence⣠of a start-voltage pulse with supply presentâ indicates a failed start element.⤠Use an ohmmeter with the kit removed â˘to check overload continuity at â¤ambient temperatureâ and to measure the âŁstart device resistance; if âthe overload shows open continuity at ambient⣠(not hot) or the start âŁdevice shows⤠vrey high/open resistance where a low/defined value is expected, replace the⢠kit. For further⤠confirmation, compareâ measured inrush âŁcurrent with the motor’s expected start current:â no âmeasurable⣠inrush while supply is⢠present typically implicates the⢠start kit rather thanâ the compressor windings.
| Item | Description |
|---|---|
| Common (C) | Main line connection; should carry supplyâ and show continuity to overload at ambient. |
| Start (S) | Connected to start winding during â˘crank; voltage present only during startup pulse. |
| Run (R) | Connected to â¤run winding; should have supply voltage continuously â˘when compressor is running. |
Compatibility, replacement Considerationsand Step-by-Step âInstallation Guidelines for Service Technicians
The 4387535 Whirlpool refrigerator Compressor Relay Andâ Overload Start Kit contains the electromechanical components that provide starting torque to singleâphase hermetic compressor motorsâ and protect against sustained overcurrent conditions.â Technicians should understand that the relay closes the start winding âŁcircuit only during the initial milliseconds â¤of motorâ acceleration while the overload opensâ when motor current or temperature exceeds safe limits; this combination is intended for compressors âwith discrete start⤠and run terminals (commonly labeled C, S, R). Verify compatibility by matching terminal layout, harness connector type, mounting footprintand rated coil voltage to the refrigerator’sâ service manualâ or OEM parts list before installation; do not assume interchangeability between solidâstate,â PTCand relay/overload start systems without confirming the compressor motor design⢠and control method.
Follow a controlled procedure when replacing the kit to⤠avoid miswiringâ and to confirm functionality.disconnect mains power ⢠and dischargeâ any stored energy in controlâ boards before âtouching⢠terminals.Inspect the old relay/overload for heat damage or melted housings,measure⣠coil and continuity with a multimeter,and confirm the compressor’sâ start and run windings with resistance readings. After⣠installing the new 4387535 kit, restore power and observe inrush current and audible operation: a⣠properly functioning relay will engage briefly at start and the overload will remain closed unless theâ compressor draws excessive current or overheats.If the âcompressor still fails to start âor draws abnormal amps, revert âto diagnostic tests (amp clamp⢠during startup, temperature measurementsand checking for shorted windings) before replacing additional components.
- Power off and tagout⢠the appliance; remove access panels to expose compressor terminals.
- Document âand photograph terminalâ wiring and⤠connector orientation before removal.
- Remove the old relay/overload, compare terminalâ labels (C, S, R) and mounting points with the replacement kit.
- Install the new relay/overload, ensuring âŁtight, corrosionâfree connections⤠and correct seating on âcompressor terminals.
- Reinstall panels, restore powerand observe compressor start behavior; measure starting current and note relay actuation.
- if abnormal current⤠or no start occurs, âpower down and recheck âwiring, then perform winding resistance andâ insulation tests.
- Verify longâterm operation by monitoring run current and runtime temperature; replace additional components âonly âŁafter diagnostic confirmation.
| Item | Description |
|---|---|
| Function | Provides timed start winding engagement âŁand thermal/electrical overload protection for singleâphase compressors |
| terminal Labels | Common (C), Start â¤(S), Run (R) – confirm âmatchâ with compressor studs |
| Typical Voltage | Nominal â120 VAC coil drive in most⣠household units; confirm with âservice spec |
| common Faults | Intermittent starting, humming compressor, high starting current, visible heat or melted housing |
Q&A
What is the 4387535 Whirlpool Refrigerator Compressor Relay and Overload Start Kit and whatâ does it do?
The 4387535 kit is an OEM start device assembly that contains a compressor start relay and an⢠overload protector (start kit) used on certainâ Whirlpool refrigerators. â˘The relay provides a momentary boost to the compressor start winding âto get the motor running; the overload protects the compressor motor from âexcessive current and heat by opening if the â˘motor draws too much current or overheats.
what symptoms indicate the relay or overload in this kit is failing?
Common⢠symptoms â¤include: repeated clicking or chatter from the compressor area,â the⣠compressor humming but not â˘starting, intermittent âcooling, the refrigerator staying warm, frequent circuit breaker tripsand the â˘compressor housing becoming unusually hot. These point to â˘aâ failed start relay/overload or a compressor that is hard to start.
how âcan I confirm this â¤part is compatible⢠with âŁmy refrigerator?
Check the refrigerator model number (onâ the VIN/serial sticker inside the cabinet or onâ the back). Crossâreference that model number with Whirlpool parts lists, the part number 4387535or the parts fiche.Don’t rely on visual similarity alone – use the model/part⤠crossâreference to confirm fit and terminal configuration.
Can âI install the 4387535 kit myself and what are the basic installation âsteps?
Yes, a competent DIYer can install it,â but always disconnect mains power frist. Typical steps: unplug the refrigerator, move it away from the wall, locate⤠the compressor âat the rear-bottom, remove the protective cover, note the orientation and wiring, âŁdetach the âold relay/overload from the compressor (usually âspade terminals and a clip), install the new kit in⣠the same position, reconnect the spade terminals,â reinstall â˘the coverand restore power. Use basic hand tools (screwdriver, pliers) and avoid bending â˘or nicking wires. If you’re unsure, hire a⣠qualified appliance technician.
How can I test the relay and overload before replacing them?
Always remove â˘power first and disconnect the relay/overload from⢠the compressor terminals. Use a multimeter to check for continuity: the overload protector should show continuityâ at room temperature (open⢠if blown). A relay may showâ open/short or erratic readings; a shake test (gentle) mayâ revealâ internal rattle indicating failure. Do not attempt live testing on the compressor terminals without proper knowledge.If in doubt, replace the start kit – they are relatively âinexpensive compared⢠with a bad⣠compressor.
After I â¤replace theâ relay and overload the compressor⣠still won’t start – what could be wrong?
Possible âŁcauses include: a seized⢠or internally damaged compressor (locked rotor),a failed âcompressor start orâ run winding,a sealed refrigerant system fault,bad âwiring or a control boardâ problem,or incorrect part fitment. A technician âcan measure compressor âwinding resistances and line voltage at⣠the compressorand perform further diagnostics. If the compressor is seized, replacing⣠the⢠start kit will not fix the problem.
Is the 4387535 kit⣠a hardâstart kit or does it include a start capacitor?
No. The 4387535 is a start relay and overload protectorâ assembly, not a hardâstart capacitor kit. Hardâstart kits include a start capacitor (and sometiems a potential relay or PTC) to give a larger starting boost; those â¤are different partsâ and are used only when recommended for the specific compressor type.
Can aâ bad relay/overload damage the compressorand how long will a âreplacement last?
A failing relay/overload can stress a compressor by allowing repeated â˘failed start attempts or by âfailing to disconnect during an overload, wich⤠can contribute to motor overheating and damage over time. Lifespan varies widely (monthsâ to many years) depending on operating conditions, power qualityand⢠compressor health. Installing a properâ OEM relay/overload when symptoms appear helps prevent further damage,and if you suspect⤠repeated overheating âor⣠hard starts,have a technician evaluate the compressor and sealed system.
Future Outlook
The 4387535 Whirlpool refrigerator âcompressor relay and overload start kit â¤plays a critical role in initiating and protecting the compressor âmotor, ensuringâ reliable start-up, preventing overheatingand maintaining consistent cooling performance. As â¤a compact but essential component⢠ofâ the refrigeration system, the kit helps extend equipment life, reduce the risk of compressor failureand support overallâ appliance efficiency⤠when installed and operated correctly.
Because symptoms of a failing relay orâ overloadâ device can resemble other issues-such as refrigerant problems⣠or electrical faults-accurate⣠diagnosis is important before â˘replacing parts. When replacement is required, using the correct 4387535 kit and following âmanufacturer guidelines orâ qualified service procedures helps restore reliable operation and avoids unnecessary repairs. For safety and long-term performance, homeowners âŁand technicians should prioritize proper testing, correct⤠installationand timely replacement when faults are confirmed.
Professional Appliance Service
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