Learning how to install hard start kit components is often the only way to save an LG or Kenmore Elite refrigerator that has stopped cooling. If you hear a loud “click-buzz-click” noise from the back, your compressor is mechanically trying to start but likely lacks the momentum to spin.
Before you spend $800 on a repair technician or $2,000 on a brand new refrigerator, there is a “Hail Mary” repair that appliance technicians have used for decades to save aging appliances: the Hard Start Kit (commonly referred to as a “3-in-1”).
This small, inexpensive device replaces your fridge’s aging start relay, overload protector, and capacitor with a single, pre-wired, powerful unit. It provides the extra electrical torque needed to jolt a stuck or “tight” reciprocating compressor back to life, potentially adding years to your appliance’s lifespan.
In this comprehensive guide, we will walk you through exactly how to install hard start kit wiring on an LG or Kenmore fridge. We will cover the critical difference between standard and linear compressors (a mistake here can be fatal to your fridge), how to map your compressor pins using a multimeter, and the step-by-step installation process.
What Is a Hard Start Kit and Why Do You Need It?
To understand why you need to install hard start kit devices, you first need to understand how your refrigerator works. The compressor is essentially a large motor pump. Like a car trying to start in cold weather, this motor requires a massive momentary surge of electricity (torque) to get spinning from a dead stop.
In a factory-standard fridge, this startup sequence is managed by three separate small components:
- The Start Relay (PTC): Routes power to the start winding for a split second.
- The Overload: Protects the motor from burning out if it stalls.
- The Run Capacitor: Helps maintain efficiency once the motor is running.
Over time, the mechanical piston inside your compressor gets “tight” due to friction and wear. The factory-installed relay simply doesn’t provide enough “juice” to turn it over anymore.
When you install hard start kit units, you are replacing those weak factory parts with a robust system that includes a much larger start capacitor. This delivers a massive “kick” of voltage—often 250% to 300% more torque—to force the compressor to start spinning.
CRITICAL WARNING: Check This Before You Install Hard Start Kit
This is the most important section of this entire article. Before you buy an LG refrigerator hard start kit, you must verify exactly what type of compressor is sitting in the back of your machine. LG and Kenmore Elite models use two very different types of technology, and they are not compatible.
1. Standard Reciprocating Compressor (Safe)
These are the traditional black “football” tanks found in most older fridges and many Kenmore models. They run on standard 115V AC power and run at a single constant speed.
Verdict: YES, you can proceed to install hard start kit on these models safely.
2. LG Linear Compressor (NOT Safe)
Many modern LG and Kenmore Elite fridges (especially those made after 2010) use a “Linear Compressor.” These are technically advanced motors driven by a computer inverter board that varies the voltage frequency to save energy. They do not use a standard start relay.
Verdict: DO NOT install a hard start kit on a Linear Compressor. If you attempt to wire a hard start kit to a linear compressor, you will blow up the expensive inverter board and destroy the compressor instantly.
How to Identify Your Compressor Type
Pull the fridge out and remove the back panel. Look for the white sticker/label on the compressor tank itself.
- Safe to Install: Look for “FLA” (Full Load Amps), “LRA” (Locked Rotor Amps), and “115V ~ 60Hz”.
- Do Not Install: Look for words like “Inverter,” “Linear,” “BLDC,” or a voltage range like “0-220V” or “53-150Hz”.
Tools You Will Need to Install Hard Start Kit
Installing a Kenmore Elite hard start kit is a straightforward electrical job, but precision is key. You cannot guess the wiring connections. Here is your packing list:
- The Part: A generic “3-in-1 Start Kit”. Model RCO410 is the most common for residential fridges from 1/4 to 1/3 HP.
- Wire Strippers/Crimpers: You will need to cut and strip the old fridge wires.
- Screwdriver/Nut Driver: usually a 1/4″ hex driver to remove the back panel.
- Electrical Tape and Wire Nuts: Essential for securing the high-voltage connections safely.
- Multimeter: This is non-negotiable. You must use a multimeter to identify the compressor pins.
- Zip Ties: To mount the new heavy capacitor so it doesn’t vibrate.
1. [The Part] Check Price for Supco RCO410 Hard Start Kit on Amazon
Step 1: Safety and Preparation
Unplug the refrigerator. We cannot stress this enough. You are working with the main power line of the appliance. Never work on a compressor while it is connected to power.
Once unplugged, move the fridge away from the wall and remove the lower access panel (usually cardboard or thin metal) to expose the compressor compartment. Clean out any dust bunnies you see around the coils while you are back there.
Step 2: Remove Old Parts Before You Install Hard Start Kit
Locate the plastic box attached to the side of the compressor. This is the old start relay assembly. It might be white, black, or brown.
- Use a flathead screwdriver to pop the wire bail (metal clip) holding it on.
- Pull the relay straight off the three metal pins sticking out of the compressor. It might be stuck tight; wiggle it gently but pull straight to avoid bending the pins.
- Identify the Fridge Wires: You will see two main wires coming from the fridge supplying power to this relay. Usually, one is White (Neutral) and one is Red or Black (Line/Power).
- Cut the Wires: Cut the old relay off the wires. Try to cut as close to the relay as possible to leave yourself plenty of wire length to work with.
- Strip the Wires: Strip about 1/2 inch of insulation off the ends of these two fridge wires. If you don’t have a stripper tool, this is the time to get one—using scissors often damages the copper strands.
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Note: If your fridge has a separate run capacitor (a white cylinder mounted nearby), you can disconnect and remove it. The 3-in-1 kit replaces that function as well.
Step 3: Identify Pins to Install Hard Start Kit Correctly
This is the hardest part of the installation and where most DIYers make mistakes. The compressor has three metal pins arranged in a triangle. To install hard start kit wiring correctly, you must know which pin is Common (C), Start (S), and Run (R).
The orientation of the triangle changes by brand. On some LGs, the single pin is at the top. On others, it is at the bottom. Do not guess. You need a Digital Multimeter to be 100% sure.
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The Multimeter Pin Test Logic:
- Set your multimeter to the lowest Ohms (Ω) setting.
- Draw a Triangle: On a piece of paper, draw the three pins as you see them.
- Measure Resistance: Measure the resistance between all three possible pairs of pins (Pin 1-2, Pin 2-3, Pin 1-3) and write down the numbers.
- Find the Highest Number: The two pins that give you the highest resistance reading are the Start and Run pins. This means the third pin (the one you are not touching) is your Common (C) pin. Label it “C”.
- Find Start vs Run: Now that you know which one is Common, place one probe on Common. Touch the other probe to one of the other pins.
- The pin with the higher resistance reading to Common is your Start (S) pin.
- The pin with the lower resistance reading to Common is your Run (R) pin.
Tip: Double-check your work. Common + Start resistance plus Common + Run resistance should equal the total resistance of Start + Run.
Step 4: Wiring the Hard Start Kit
Now that you have mapped your pins, the actual wiring is simple. Your new RCO410 Hard Start Kit comes with three wires attached to a black cylinder. The standard color code for a Supco RCO410 is universal:
- Black Wire: Connects to the Common (C) pin.
- White Wire: Connects to the Start (S) pin.
- Red Wire: Connects to the Run (R) pin.
Connecting to the Pins
Push the female spade connectors of the Hard Start Kit onto the corresponding pins you identified in Step 3. Ensure they are tight. If the connectors feel loose on the pins, use needle-nose pliers to squeeze them slightly for a tighter fit. A loose connection here will cause arcing and failure.
Connecting to Power
Now, look at the two black wires coming out of the Hard Start Kit casing (these are the power input wires). Connect these to the two power wires coming from the fridge (the ones you stripped in Step 2).
- Connect one Kit wire to the Fridge Line wire (Black or Red).
- Connect the other Kit wire to the Fridge Neutral wire (White).
- Polarity: Since this is AC current, it generally does not matter which black kit wire goes to which fridge wire, but keeping them secure is vital.
- Use Wire Nuts to twist the connections together tightly, and wrap the nuts with electrical tape to prevent them from vibrating loose.
Step 5: Final Mounting Steps
The Hard Start Kit is significantly heavier than the old plastic relay. You cannot let it dangle by the wires connected to the compressor pins. The vibration of the compressor will shake the connectors loose within days.
- Find a secure spot to mount the black cylinder. You can strap it to a nearby copper pipe (insulate it if needed) or the metal frame of the fridge base.
- Use a strong Zip Tie to secure it firmly.
- Ensure the wires are tucked away so they do not touch the condenser fan blade or the hot compressor tank.
- Plug the refrigerator back in.
How to Verify Success After You Install Hard Start Kit
Once you plug the fridge in, listen carefully.
- Success Indicators: You should hear a solid “Click” followed immediately by a strong, low-pitched hum. This is the compressor running. Check the evaporator coils in the freezer after 20 minutes; they should be getting frosty.
- Failure Indicators: If you hear a click, a hum for 10 seconds, and then another click (and silence), the compressor is still tripping the overload. The hard start kit was not enough to save it. If you hear nothing at all, check your wire nut connections—one may have come loose.
FAQ: Common Questions on Installation
Is it difficult to install hard start kit units for a beginner?
No, it is generally considered a beginner-to-intermediate DIY repair. The most “technical” part is using the multimeter to identify the pins. As long as you follow the triangle test logic in Step 3, the actual wiring takes less than 15 minutes.
Why is my compressor hot after I install hard start kit?
Compressors run hot naturally (up to 150°F is normal). However, if it is scorching hot to the touch (you can’t keep your hand on it for 1 second) and it shuts off frequently, the internal windings might be shorted. In this case, the compressor is dead and the kit cannot save it.
Can I use this on a GE or Whirlpool fridge?
Yes. While this guide focuses on LG and Kenmore, the RCO410 Hard Start Kit is universal for almost all domestic refrigerators sized 1/4 to 1/3 HP. The installation steps and pin identification process are exactly the same.
Conclusion
Learning how to install hard start kit devices on an LG or Kenmore fridge is a valuable skill that can save you from an emergency appliance purchase. For less than $20 and 30 minutes of work, you are giving your aging compressor the electrical “jump start” it needs to keep your food cold.
However, remember that a hard start kit is often a temporary solution for a dying compressor. It may last 5 years, or it may last 5 months. Use the time it buys you to start saving for your next refrigerator.
One major reason compressors fail is overheating due to dirty coils. To ensure your new hard start kit lasts as long as possible, we recommend cleaning your coils immediately after installation.
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Need more help? Read our full guide on how to clean refrigerator condenser coils safely to maximize your repair.
