Mini split auto restart and connecting an additional thermostat

September 16, 2009 by Shawn Mack  
Filed under Ask Thomas

First Name:  Don

Last Initial:  M

Problem: Our split system is controlled by a remote. Every time the power goes out the system has to be manually turned on.This is a problem because our power goes out quite frequently and we have pets and are not always home to turn the unit back on.Can a thermostat be hard wired or is there some other solution?  Thanks

Solution:  Most mini split air conditioners have an “auto restart” function that turns the evaporator back on after a power failure.  When power returns the indoor evaporator’s electric circuit board will restart the system to the last setting before the power failure.  If you had the unit set at 77 degrees before the power failure it will return to 77 degrees at restart.  Make sure your equipment has the “auto restart” feature.  If it does you probably need the indoor evaporator circuit board replaced.

Mini split air conditioners are not built to have an external thermostat.  In order to attach a thermostat they would need to have an extra wire built into the circuit board.  They do not, therefore it is not possible..