Replacing Just the Evaporator of a Mini Split.

February 10, 2009 by Shawn Mack  
Filed under Ask Thomas

Written by Megan A:


My inside evaporator will not come on.  I have checked the power, checked the fuses inside the cover, changed the batteries in the remote. Can I use the same compressor and just buy the inside unit or do I have to buy the compressor and evaporator. I have looked everywhere and can not find just the inside unit. I hate to throw away the compressor.

Solution:  After checking that power is indeed reaching the indoor evaporator and the fuse is still intact you most likely have a circuit board failure.  Many manufacturers call it a “PCB Board” and it is a relatively easy repair.  Call your manufacturer to purchase the correct part.  Most manufacturers will have a one year warranty on the circuit board.

If you need to purchase a new evaporator there should not be a problem swapping it with the older unit.  Make sure the model number of the new evaporator matches the old evaporator.  A HVAC installer will be needed to vacuum the line set and recharge the entire system’s refrigeration.  The only difficulty I see is if you have an older 10 SEER evaporator and the only thing available is the newer 13 SEER evaporators.  The two systems will not be compatible.  You will also have to find a distributor that will sell only the evaporator.

Ductless Mini Split Electrical Requirements

January 8, 2009 by Shawn Mack  
Filed under Installation Guide, Technical Guide

“Before purchase of a mini split air conditioner make sure you have an available circuit breaker in your electrical box.”

Installation of mini split air conditioners requires the ability to work with both refrigerants and electricity.  When purchasing any ductless air conditioner be aware of the voltage requirements in the manufacturer specifications.  The most common electrical specifications will require either 110 volt or 220 volt wiring. 

When searching for mini split air conditioners remember that 110 volt systems are generally only used on units 12,000 btu. or less.  Anything above 12,000 btu. will be manufactured 220 volt.

Unlike window air conditioners that plug into electrical receptacles, most mini split air conditioners are hard wired from the electrical fuse box.

Generally, mini split outdoor condensers receive power from the electrical fuse box through an outdoor disconnect box for safety.  Always use a disconnect box when wiring mini split air conditioners. 

Check with the local electrical safety code for the proper distance between the disconnect box and the mini split condenser.  In most cases the disconnect box should be located close enough to pull the power while standing at the outdoor condenser.

The indoor evaporators receive power directly from the outdoor condenser.  Electrical wiring is run alongside the refrigerant line set.

Make sure to check the requirements for proper electrical wiring gauge.  The systems I have worked with used 14 gauge high voltage wiring for the entire system.

Proper breaker size is also very important.  Before purchase of a mini split air conditioner make sure you have an available circuit breaker in your electrical box.  Ductless air conditions require the use of its own circuit breaker. 

A dual pole 20 Amp circuit breaker handles most manufactured mini split systems up to 24,000 btu.  Make sure to check with the manufacture specifications for proper circuit breaker sizing.

Make sure to contact your city hall to obtain the proper permit for the electrical work being performed.