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Mitsubishi MHK2 RedLINK Thermostat Setup Guide

Step-by-step instructions to install and configure your Mitsubishi MHK2 wireless thermostat for ducted HVAC systems.

Required Tools

  • Phillips screwdriver
  • Level
  • AA batteries (2)

What's Included

Your MHK2 kit includes the MRCH2 Remote Controller (thermostat), MIFH2 Wireless Receiver with cable, wall plate and mounting hardware, and 2 AA alkaline batteries.

Safety First

Before starting installation, always disconnect power at the circuit breaker. This thermostat must be installed by a trained technician per manufacturer guidelines. Read all instructions carefully before beginning.

Important Warnings:

  • DISCONNECT POWER before starting installation
  • Installation must be performed by trained technician
  • Do not cut or modify the receiver cable

Connect the Wireless Receiver

The wireless receiver connects to your indoor unit control board and enables communication with the thermostat.

Steps:

  1. Attach the cable to the CN105 connector on your indoor unit control board
  2. Mount the wireless receiver near the indoor unit (within range)
  3. Do not cut, modify, or extend the cable

Pro Tips:

  • The receiver should be mounted in a location with clear line-of-sight to the indoor unit
  • Avoid mounting near large metal objects that could interfere with the wireless signal

Mount the Wall Plate

Choose your mounting method based on your wall type and preference.

Steps:

  1. Direct Wall Mounting: Position wall plate on wall and mark hole positions (ensure level)
  2. Drill 7/32" holes for drywall anchors
  3. Tap supplied wall anchors into wall
  4. Attach wall plate with supplied screws
  5. Junction Box Mounting (Optional): Separate junction box adapter from cover plate
  6. Mount adapter to electrical box using any of 8 screw holes
  7. Hang wall plate on top hook and snap bottom into place
  8. Attach cover plate

Pro Tips:

  • Mount approximately 5 feet from floor in frequently used area
  • Avoid air drafts, dead air spots, and direct sunlight
  • Avoid locations near concealed chimneys or stovepipes
  • Use a level to ensure straight installation

Install Batteries & Link System

Insert batteries and complete the initial pairing between the controller and your HVAC system.

Steps:

  1. Insert 2 AA alkaline batteries into the MRCH2 controller
  2. Align controller with wall plate and push gently until it snaps in place
  3. Controller displays 'Wait' screen while detecting the A/C unit
  4. After detection, screen changes to 'Initial Installer Setup' with 'START SETUP'
  5. System automatically searches for A/C support and loads indoor service unit options

Configure Function Codes

Advanced settings are automatically configured by your HVAC equipment. Access if needed by pressing and holding the Menu button for 5 seconds. Setup may take up to 40 seconds to enter and 30 seconds to exit.

Basic Operation

Learn the essential functions to control your system.

Steps:

  1. Adjust Temperature: Touch + or - buttons on home screen
  2. Change Mode: Press Mode button and select Heat, Cool, Dry, Fan, Auto, or Off
  3. Wake Screen: Press center area of displayed temperature (screen stays lit for 10 seconds)
  4. Schedule Programming: Go to Main Menu → Select 'Schedule' → Define settings for Wake, Leave, Return, Sleep periods
  5. Fan Speed: Select from Auto or speeds 1-5

Important Notes

Key information about your MHK2 system.

Pro Tips:

  • One controller per air handler - each indoor unit needs dedicated controller and receiver
  • No built-in WiFi - MHK2 uses RF RedLINK connection only
  • For smart control via Kumo Cloud, requires separate PAC-USWHS002-WF-2 adapter
  • Temperature source options: MHK2 built-in thermistor (default), optional RedLINK Indoor Air Sensor, or average of both

Troubleshooting Error Codes

Common error codes and solutions:

Steps:

  1. Error 134 (Weak Signal): Move wireless device to different location for better signal strength
  2. Error 137 (Maximum Clients): Too many devices connected to system
  3. Error 153 (Timeout): Check connection and retry pairing process

Frequently Asked Questions

Can I control my MHK2 from my smartphone?

The MHK2 itself does not have built-in WiFi. To control your Mitsubishi system remotely, you'll need to add a separate PAC-USWHS002-WF-2 WiFi adapter for Kumo Cloud smart control.

What's the difference between the MHK2 and Kumo Cloud?

MHK2 is a wireless thermostat that uses RF RedLINK to communicate with your indoor unit. Kumo Cloud is a separate WiFi adapter that enables smartphone control through an app. You can use both together for the best of both worlds.

How often should I replace the batteries?

Under normal use, the 2 AA batteries should last approximately 1 year. The thermostat will display a low battery warning when replacement is needed.

Can I control multiple zones with one MHK2?

No, each indoor unit requires its own dedicated MHK2 controller and wireless receiver for independent zone control.

Need Professional Help?

Our certified technicians can install and configure your Mitsubishi MHK2 RedLINK thermostat professionally.

Call (925) 578-3293 Schedule Online

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