3 Reasons your car leaking water when ac is on

It’s important to understand that water dripping from under the car when ac is on is normal. But, when it goes to your car compartment, it's unusual condition an need to be repair immediately.

Your car’s air conditioning system may leak water inside the vehicle. If leaks aren’t fixed quickly, the carpet and padding underneath can become a breeding ground for harmful bacteria and mildew. People with certain allergies can be affected the most. So, here's 3 reasons your car leaking water when ac is on

1. Clogged drain tube and hose

The first reason your car leaking water when ac is on is clogged drain tube. This drain tube is connected to the HVAC (Heating, Ventilation & Air Conditioning) case in your car Air conditioning system. While in the HVAC case, there are several AC components such as the evaporator, motor blower and cabin filter.

As we know, water dripping from under the car when the A/C is on is normal. This is common reason because when car air conditioner is working, the evaporator will condensate so that it can produce water.

The condensed water will fall at the bottom of the HVAC case and will flow towards the drain tube. Thus, the case is also designed to allow water to flow to the bottom and out the drain tube.

Usually the clogged drain tube is caused by debris in the case, like dirt or leaves. When the drain tube becomes clogged, the HVAC case will be filled with water.

Otherwise, the case is not designed to be completely water tight. Sometimes if excess water remains in the case, some of it can blow out of the AC vents. In extreme cases the water can damage the blower motor and/or short out the blower resistor.

2. Drain tube detached from HVAC case or firewall

The second reason your car leaking water when ac is on is the drain tube detached from HVAC case or car firewall. Drain tube is connected with drain rubber hose. One side is connected to the HVAC and the other side is sticking out the vehicle through a firewall.

The easy part detached drain tube is on the side that is connected between HVAC and car firewall, because of this location is close to the foot and can easily pulled out and detached from HVAC or car firewall. This opened drain tube will make the water run from the HVAC hole and drip into the car compartment.

Read Also:

• Changing cabin air filter (Under Dash Type)
• The causes of noisy AC blower motor

3. HVAC Case leaking

Some car HVAC case designed with groove and tongue system that has no sealer from the factory. This design system is quite weak if the HVAC case is distorted excessively. If the case becomes slightly distorted, it can allow water to blow past this seam and leak onto the carpet near the drain.

In other cases, improper installation for HVAC case after a repair is a common reason for a leaking water. Poor installation practices can present a host of problems, many of which lead to water leakages through HVAC case.

Sometimes, the locking system in HVAC case have been improperly installed, unsealed, and loosen over time. This allows the condensation to drain water onto the carpet.