Mini Split Installation & Commissioning
Complete field checklist — site assessment through customer sign-off
Mini Split — Install & Commission
Complete each step in order. Flag any item with an abnormal finding or that needs follow-up.
1. Site Assessment & Pre-Install
Indoor Unit Location
Confirm wall is structurally sound, unit is centered in zone, and clearances meet manufacturer specs
Outdoor Unit Location
Verify pad or wall-mount location — level surface, airflow clearances met, not in direct sun or tight enclosure
Line Set Path Planned
Map lineset route — shortest path, avoid sharp bends, confirm penetration location through wall
Permits & Code Requirements
Confirm permit pulled if required by local jurisdiction. Verify electrical code compliance for branch circuit
2. Line Set Installation
Core Drill Wall Penetration
Drill penetration hole at slight downward angle toward outside for drainage. Seal with foam or sleeve after install
Flare Copper Line Set
Cut tubing square, deburr, and flare both ends — inspect flares for cracks, off-center, or uneven surface before connecting
Insulate Line Set
Both suction and liquid lines fully insulated — no gaps, tears, or exposed copper. Tape all seams
Line Set Cover / Whip
Install line set cover or conduit along exterior wall. Secure at every 24 inches minimum. Seal wall penetration
3. Indoor Unit Installation
Mount Backing Plate
Level and secure mounting plate to wall — verify it is plumb and lag screws hit studs or proper anchors
Connect & Route Condensate Drain
Connect drain hose to indoor unit, route with proper slope (1/4" per foot min) to drain point or condensate pump
Connect Line Set to Indoor Unit
Route copper lines and communication/power wire through wall. Connect and torque flare connections on indoor unit
Hang Indoor Unit
Hook unit onto mounting plate and verify it is fully seated and level. Check drain pan is properly aligned
4. Outdoor Unit Installation
Set Outdoor Unit on Pad or Bracket
Place outdoor unit on level surface. Install vibration isolation pads. Verify unit is not tilted
Connect Line Set to Outdoor Unit
Connect and torque flare connections on service valves. Do not open service valves until after evacuation
Confirm Service Valves Are Closed
Both liquid and suction service valves must remain fully closed until after vacuum is pulled and broken correctly
5. Electrical
Dedicated Branch Circuit
Install dedicated breaker and wire sized per nameplate MCA and MOP. Verify correct breaker amperage
Outdoor Disconnect
Install lockable outdoor disconnect within sight of unit per NEC requirements
Connect Power to Outdoor Unit
Connect power wiring to outdoor unit terminals per wiring diagram. Verify L1, L2 (and neutral if applicable) are correct
Communication / Signal Wire
Run and connect communication wire between indoor and outdoor unit per manufacturer wiring diagram (S1/S2 or A/B terminals)
Verify Voltage at Unit
Energize circuit and verify voltage at outdoor unit terminals matches nameplate rating before starting unit
6. Pressure Test & Evacuation
Pressure Test with Nitrogen
Pressurize system through service ports to 150–200 psig with dry nitrogen. Leak check all flare connections and joints
Triple Evacuation
Evacuate to 300 microns or lower. Break with dry nitrogen, re-evacuate — repeat 3 times. Final hold must be stable at 500 microns or below
Open Service Valves
After vacuum holds, open both liquid and suction service valves fully. Do not crack valves before vacuum is confirmed stable
7. Commissioning & Startup
First Power-On & Mode Test
Power on system, run through all modes (Cool, Heat, Fan, Dry) to verify basic operation and no fault codes
Operating Pressures
Connect gauges and document suction and discharge pressures at steady-state in cooling mode
Superheat / Subcooling Verified
Verify superheat and subcooling readings are within acceptable range for the refrigerant and conditions
Amperage Draw
Measure running amps on compressor and confirm within nameplate RLA at steady-state
Delta T Check
Measure supply air temp vs return air temp — expect 16–22°F split across the indoor coil
Remote Control & WiFi Setup
Test all remote functions. Set up WiFi app control if applicable and confirm customer can operate system
Final Inspection — Noise & Vibration
Confirm no abnormal noise, rattle, or vibration from indoor or outdoor unit at multiple fan speeds
8. Documentation & Close-Out
Photo Documentation
Photograph indoor and outdoor unit installations, line set routing, electrical connections, and gauge readings
Warranty Registration
Register system warranty with manufacturer. Note model, serial number, and install date for both indoor and outdoor units
Customer Walk-Through & Sign-Off
Walk customer through system operation, filter location, maintenance schedule, and warranty terms. Obtain signature
Note: Never open outdoor service valves before completing a full triple evacuation. Pre-charged units contain the refrigerant charge in the outdoor unit — opening valves prematurely releases refrigerant into a non-evacuated system.
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