Only One Room Cooling? Other Aircon Units Not Working?

In multi-split setups (1 outdoor, multiple indoor units), it’s common for one room to stay cool while the others struggle or shut off. Don’t assume the problem is isolated. Most of the time, it’s a shared fault affecting pressure, control, or load balancing across the entire system.

Why Some Indoor Units May Stop Cooling

1. Gas imbalance

Multi-split systems share refrigerant. If there’s a leak or undercharge, units furthest from the compressor usually fail first.

2. Expansion valve fault (EEV)

Some brands have individual metering valves per unit. If one fails, that specific indoor unit won’t receive proper gas flow.

3. Fan motor or coil blockage in one unit

If airflow is compromised in one indoor unit, it may shut down — or freeze — while others keep running. The issue may look isolated, but causes cooling disruption system-wide.

4. Control board sync error

If communication between indoor and outdoor units is disrupted, some zones may receive cooling signals, while others don’t.

5. Compressor struggling under partial load

A weak compressor may keep the closest unit working — but fail to push refrigerant evenly to all branches. This usually signals a pending full failure.

What You Can Check First

• Is one room cooling, others not blowing air at all?

• Are fans working in all indoor units?

• Any flashing lights or error codes on affected units?

• Did the problem start after servicing or a power trip?

If more than one indoor unit is behaving erratically, the issue is system-wide — not just local.

Why It Matters

Partial failure is often the first warning before full breakdown.

If ignored:

• Compressor damage may follow

• Gas leaks may worsen

• Full shutdown may occur without warning

• System efficiency drops across all zones

One room cooling doesn’t mean the system is healthy. It means the system is trying — but struggling.

When to Book a Diagnostic

✅ Some indoor units cooling, others not

✅ No error code, but performance is uneven

✅ Issue occurs on and off — not consistently

✅ Fan blows, but air not cold in specific zones

We’ll test refrigerant balance, valve control, PCB sync, and system response — across all heads, not just one.