Split Type AC Wiring Diagram

 

Fig-Split Type AC Wiring Diagram

What is the Split Type AC (Air Conditioner) Wiring Diagram?

A split AC or air conditioner has two main assemblies: the indoor unit (evaporator, blower, PCB) and the outdoor unit (compressor, condenser fan, contactor/capacitor). They are connected by a power supply and a multi‑core interconnecting cable that carries power, earth, and control/communication signals between the two units. 

Key components and their electrical connections for Split Type AC (Air Conditioner)

• Main power supply
  • Single‑phase 220–240 V (or 110–120 V in some markets) feeds the outdoor unit or a dedicated breaker/isolator; some systems feed the indoor unit instead—follow the manufacturer's diagram. 
• Interconnecting cable (indoor ↔ outdoor)
  • Typical cores: Live (L); Neutral (N); Earth (E); Signal/communication (S) or control. Some mini‑splits use 3‑core (L, N, E) plus a separate low‑voltage control pair; others use 4–5 cores for power + communication.
• Protection devices
  • MCB / fuse on the supply; isolator/disconnector near the outdoor unit; surge protection recommended for outdoor compressor. 
• Outdoor unit internals
  • Compressor motor (to contactor/relay), run capacitor, overload protector, condenser fan motor, and the outdoor PCB that interfaces to the indoor PCB via the signal wires.
• Indoor unit internals
  • Fan motor, evaporator thermistor(s), PCB (control board), display/remote receiver; the indoor PCB sends/receives commands and status over the communication pair. 

---

Typical wire color/function table for Split Type AC Wiring

Wire	Typical color	Function
L (Live)	Brown; Red	Main phase to the motors/contactor
N (Neutral)	Blue; Black	Return conductor for the AC supply
E (Earth)	Green/Yellow	Protective earth
S (Signal/Comm)	White; Yellow; Grey	Control/communication between PCBs

---

Typical wiring layout (step‑by‑step) for a split-type AC wiring diagram

1. Isolate power at the distribution board.
2. Run supply cable from a dedicated breaker/MCB to the outdoor unit isolator (or indoor unit if specified). Size cable per rated current. 
3. Run an interconnecting multi‑core cable between the indoor and outdoor units through the refrigerant pipe chase. Include an earth conductor.
4. Connect supply to outdoor unit: L → outdoor supply terminal; N → neutral terminal; E → earth terminal. Fit MCB/fuse as required. 
5. Connect the interconnect to the indoor unit: match L, N, E, and signal wires to the indoor PCB terminals (labelled L, N, E, CN/COM/Signal). Ensure polarity and terminal labels match the manufacturer's diagram.
6. Verify control wiring: the communication pair must be connected to the correct indoor/outdoor PCB terminals (often labelled TX/RX, CN, or COMM).
7. Earthing: bond both units to the same protective earth. Test continuity. 
8. Power up and test: check MCB, measure supply voltage, run the unit through modes, and verify compressor start, fan operation, and remote/thermostat control.

---

Cable sizing and protection (practical guidance)

• Cable size depends on unit rated current and run length. As a rule of thumb, small split units (<2.5 kW) often use 2.5 mm² for power; larger units require 4 mm² or 6 mm². Always calculate using the unit’s nameplate current and local wiring regulations. 
• MCB rating should match the unit’s full‑load and starting current per the manufacturer. Use a time‑delay fuse or appropriately rated MCB for compressor inrush. 

---

Safety, common mistakes, and troubleshooting tips for split-type AC wiring

• Always follow the manufacturer’s wiring diagram — terminal labels vary by brand and model. 
• Do not omit earth; lack of proper earthing is a major safety hazard. 
• Wrong signal wiring (swapped comm pair) causes communication faults; check LED fault codes on PCBs. 
• Voltage checks: measure the supply at the unit before connecting; low voltage can prevent the compressor from starting.
• If the unit trips the breaker on start, check capacitor health, contactor wiring, and correct MCB sizing.

---

Quick reference checklist before powering up the air conditioner

• Dedicated breaker/MCB installed and labelled.
• Interconnecting cable cores are correctly matched and secured.
• Earth continuity verified between indoor and outdoor units.
• Manufacturer terminal labels confirmed and followed.
• Surge protection and isolator fitted if required.