5-2-1 CSR-U1 Hard Start Capacitor Kit for 1 to 3 Ton AC Units
5-2-1 CSR-U1 hard start capacitor kit with relay, wiring, and mounting hardware for 1 to 3 ton AC units.
5-2-1 CSR-U1 hard start capacitor kit components with labeled dimensions for 1 to 3 ton AC units.
Infographic showing benefits of 5-2-1 CSR-U1 hard start capacitor kit for 1 to 3 ton AC units.
Prewired 5-2-1 CSR-U1 hard start capacitor kit showing easy installation wiring and electrical connections.
Woman relaxing on a couch under a functioning air conditioner, promoting 5-2-1 CSR-U1 hard start capacitor DIY repair.
5-2-1 CSR-U1 hard start capacitor kit with relay, wiring, and mounting hardware for 1 to 3 ton AC units.
5-2-1 CSR-U1 hard start capacitor kit components with labeled dimensions for 1 to 3 ton AC units.
Infographic showing benefits of 5-2-1 CSR-U1 hard start capacitor kit for 1 to 3 ton AC units.
Prewired 5-2-1 CSR-U1 hard start capacitor kit showing easy installation wiring and electrical connections.
Woman relaxing on a couch under a functioning air conditioner, promoting 5-2-1 CSR-U1 hard start capacitor DIY repair.
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5-2-1 CSR-U1 Hard Start Capacitor Kit for 1 to 3 Ton AC Units

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5-2-1 CSR-U1 Hard Start Capacitor Kit

Key Features

  • Two-wire hard start kit for single-phase compressors
  • Includes a potential relay and start capacitor
  • Reduces compressor start-up time and energy consumption
  • Assists older or tight compressors with starting
  • Installs in series with the compressor run winding

Replaces / Cross-Reference Part Numbers

  • CSRU1
  • SPP6
  • SPP5
  • RCO410
  • RCO810
  • RCO410D
  • 88-5440
  • HN61PC005
  • HN61KA023
  • CKFU1

Compatibility & Fitment

  • Designed for 1 to 3 Ton (12,000 to 36,000 BTU) air conditioning and heat pump units
  • Compatible with single-phase 115V to 288V systems

When to Replace

  • Compressor hums but struggles or fails to start
  • A/C system causes significant dimming of lights on start-up
  • Circuit breaker trips when the compressor attempts to start
  • Proactive installation on older units to extend compressor life

Installation Tips

  • Disconnect all electrical power to the A/C unit before installation.
  • Safely discharge any existing capacitors in the system.
  • Connect the two wires from the kit to the compressor's "Run" and "Common" terminals.
  • Mount the device securely inside the electrical control panel.
  • Professional installation by a qualified HVAC technician is recommended.
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FAQ

The CSR-U1 model is specifically engineered for single-phase air conditioning and heat pump systems ranging from 1 to 3 tons.
If your compressor is struggling to start, dimming the lights when it kicks on, or if you hear a clicking sound followed by the unit failing to engage, your compressor may be having trouble overcoming the initial startup load. A hard start kit provides the necessary boost to get the compressor running quickly and efficiently.
This is a 3-wire installation. The black wire connects to the Common (C) terminal of the compressor. The striped wire connects to the Start (S) terminal, and the red wire connects to the Run (R) terminal.
The difference between these models is the size of the start capacitor. Using the wrong size can lead to improper starting torque. The CSR-U1 is calibrated for 1 to 3-ton units (88-106 uF range). Always verify your compressor's specific requirements to ensure you are selecting the correct model for your system's tonnage.
By providing a significant boost during the startup phase, the kit reduces the amount of time the compressor spends in the high-amperage startup cycle. This reduces heat buildup in the motor windings and helps the compressor reach full operating speed faster, which minimizes mechanical wear over thousands of start cycles per season.
The CSR-U1 is designed for standard residential 208/240V single-phase HVAC systems.