Passenger side carpet wet

Why is the passenger side carpet wet?

If you find the passenger side carpet wet, that water can come from only three places: either the windshield seal is leaking, the sunroof drains are clogged, or the condensation drain from the AC evaporator coil is clogged. A plugged drain is far more common than a leaking windshield.

Why does the condensate drain plug up?

When car makers shifted to R-134a refrigerant they had to make changes to the evaporator coil which meant the fins had to be spaced closer together. That tight spacing kept water in place longer than the older style evaporators. As air passes over these tightly packed coils, bacteria can combine with the water and start to grow mold. That mold can morph into slime that eventually clogs the drain tube. In addition, some car makers have discovered that insects are attracted to this decaying organic matter and enter the drain tube to build nests, further clogging the tube. Once the drain tube gets clogged, AC condensation can’t drain out of the heater box. So it overflows, making your passenger side carpet wet.

Plus, it gives off a musty smell from the vents

The science experiment growing in your HVAC system also emits a locker room type musty smell when you turn on the blower. This is evidence that you have mold/mildew growing on the evaporator coil.

How to fix a passenger side carpet wet condition caused by a clogged condensate drain.

Your first step is to unclog the drain tube. That tube is usually located at the bottom of the HVAC heater box on the passenger side near the console. Examine the area with a flashlight and look for a rubber tube attached to the HVAC case. If you have access to a floor jack and jack stands, find the tube under the car near the engine firewall. It’s best to unplug the line from there using a pipe cleaner or wire.

Run the pipe cleaner up through the tube and remove it until the water drains out. Then flush the line with clean water using a turkey baster (discard the turkey baster afterwards). Do NOT introduce strong cleaning solutions into this tube! Specifically, you may be tempted to fill the tube with bleach. DON’T do it. Bleach is highly corrosive and can oxidize the aluminum evaporator coil and fins, destroying it (cost approx. $1,000 to replace).

Once you open the drain line and remove the water, treat the evaporator coil with a special anti-bacterial coating with this product

See this post for more information on smelly AC

How to fix water on passenger side due to a clogged sunroof drains

Every sunroof has at least 3 drains; two in each corner of the front of the sunroof and at least one in the back. Over time, leaves and debris can clog the drains. When that happens, the water drains down the A-pillars and you wind up with a passenger side wet carpet condition. The fix is to open the sunroof and clean out the drains.

Roof drain locations

For more information on how to unclog sunroof drains, see this post

Windshield leaks

Windshield leaks are hard to find and even harder to seal. It’s best to work with an auto glass company to find and fix the leak.

However, if you find the leak on your own, here are a few tips on how to fix the leak.

Tip #1 Do NOT use household silicon

It is the wrong product and it won’t last, especially if it’s exposed to sunlight. Worse yet, once you apply silicone to the window frame or roof line, no other sealant will work after that.

Use windshield urethane instead. Find a tube of it at any auto parts store. It’s designed to adhere to glass and the steel window frame and it’s UV resistant.

Tip #2 If the leak is due to rust, fix the rust first

No sealant will last if applied to rust.

Tip #3 If you can’t get it sealed, take it to an auto glass specialist.

©, 2016 Rick Muscoplat