When people say “cooling coil leak” on a Toyota NCP151 (Vios / Yaris XP150), they usually mean one of two things. Let’s pin it down 👇

1️⃣ A/C Cooling Coil (Evaporator) Leak — MOST COMMON

This is very common on NCP151 models.

Symptoms

• A/C not cooling or slowly getting weaker

• Need to top up gas frequently

• Bad smell from vents (musty / chemical)

• Oily residue from A/C drain (rare but telling)

• No visible leak in engine bay

Why it happens

• Evaporator coil corrodes over time

• Moisture + dust buildup inside dashboard

• Thin aluminum coil develops pinholes

Fix

• Dashboard must be removed

• Replace evaporator coil (recommended, not repair)

• Replace expansion valve + O-rings

• Vacuum + refill refrigerant

⚠️ This is labor-heavy but a permanent fix

2️⃣ Radiator / Engine Cooling Leak (Less Common)

This affects engine temperature, not A/C.

Symptoms

• Engine overheating

• Coolant level dropping

• Wet spots under car

• Sweet smell from engine bay

How to confirm which one it is

Quick checks:

• ❄️ A/C weak but engine temp normal → Evaporator leak

• 🌡️ Engine overheating → Cooling system leak