Leaks & smells

Leak under the car only happens when the AC is on

A leak that only appears specifically while or right after the AC runs, and never otherwise, is almost always the normal evaporator condensation drain doing exactly what it's designed to do.

Difficulty
Easy
Time
5 minutes

Symptoms

  • Puddle or drip appears only during or shortly after AC use, never at other times
  • Water is clear and odorless
  • No puddle forms if the AC hasn't been used recently
  • No other symptoms like reduced cooling or dashboard warnings

Likely causes

  • CommonNormal AC evaporator condensation drainageThis is expected behavior; the AC condenses moisture out of the air, and that water drips out from underneath the car whenever the AC has been running.

What to do

  1. Confirm the water is clear and odorless with no color or oily texture.
  2. Note that this is completely normal and expected, especially in hot or humid weather when the AC works hardest.
  3. Only treat this as a problem if the water appears inside the cabin instead of underneath the car (see the AC-leaking-water-inside guide), or if the fluid has any color or smell.
  4. No repair is needed for a normal, clear AC condensation leak that only happens with AC use.

When to call a pro

No mechanic visit needed for this normal behavior; see one only if water leaks inside the cabin or the fluid is colored/oily instead of clear.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.