Mitsubishi Mini Split with Nest Thermostat Installation
One of the biggest complaints customers have about mini split installations is the lack of compatibility with 3rd party thermostats, such as Nest & Ecobee. While there are few manufacturers that have similar interfaces, the Mitsubishi PAC-US444CN-1 allows you to do just that. While there are some limitations to using such an interface, the benefit of being able to remotely control your mini split far outweighs these disadvantages. One such limitation is the inability to control the vane positions & fan speeds. Most mini splits have an IR remote that can be used to make these adjustments, but the Mitsubishi SLZ cassettes do not. The lack of fan speed control is a limitation of the Nest E thermostat, not the PAC interface. Using a thermostat with independent fan speed relays would allow you to control the mini split fan speed, but the Nest E does not have this functionality. For this application, we chose to let the PAC interface automatically adjust the fan speed based on the set mode.
This mini split is located in the client’s guest house and was added to the RTI automation system we installed for them. The client is able to control the main house’s Nest thermostat as well as the guest house Nest thermostat from any of their phones, iPads or RTI touch screens, as well as from the Nest app itself.
3 Replies to “Mitsubishi Mini Split with Nest Thermostat”
Curious where did you end-up installing thermostat interface: hiding within AC unit, wall, somewhere else? Also did you have to replace wire in the wall with 10 stats or so?
This was a new-construction installation so just ran a 6-wire thermostat wire from the Nest to the Mitsubishi PAC interface. The PAC interface is mounted inside the air handler control board area.
I see. Did you use any transformer to bridge millivolt with 24V?