January 6, 2015

Troubleshooting a leaking room air conditioner

By Sears PartsDirect staff
Troubleshooting a leaking room air conditioner
Troubleshooting a leaking room air conditioner

When working correctly, a window air conditioner removes moisture from the room air; that moisture collects on the evaporator coils inside. How much water collects, depends on how humid the air is. So, even when everything is working perfectly as designed, the air conditioner will drip some water from the rear outside but none from the inside.

If your air conditioner leaks water inside the room, here are some of the most common causes.

Iced-up coils

The coils inside the air conditioner can form ice if the air filter is clogged with dirt. Remove the front grill to inspect the filter. If the filter is dirty, wash the filter with water and let it dry before reinstalling it. If the coils continue to ice over, contact a service provider.

Incorrect installation

The air conditioner should be tilted back slightly so water drains outside. Check that the air conditioner is level from left to right and tipped slightly from front to rear.

Blocked drain

The rear of the air conditioner has a drain hole or notch to allow excess water to escape. Debris can clog this opening, preventing water from draining out. Use a wooden stick or skewer to unplug the opening—don’t use a metal pick or screwdriver, which could puncture the coils and cause major damage to the air conditioner. Also, don’t drill holes in the bottom of the cabinet.

Blocked drain path

Small channels allow water to drain from the front of the air conditioner to the rear. When these channels are blocked, water collects in the front of the cabinet and can’t drain to the rear.

Pull off the front grill and remove the filter. If you see a pool of water under the coil but little or no water in the back, these channels could be blocked. Remove the air conditioner from the window and use a low-pressure water hose to flush out these channels and the drip pan.

Symptoms for window air conditioners

Choose a symptom to see related window air conditioner repairs.

Main causes: bad compressor, lack of refrigerant, bad compressor start relay, electronic control board failure
Main causes: turning the air conditioner off and the back on too quickly, dirty or restricted condenser coil, compressor failure
Main causes: dirty air filter, air conditioner is too small for the room, temperature set too cold, control failure
Main causes: clogged drain hole, air conditioner not leveled properly
Main causes: clogged condensate drain, air conditioner not leveled properly, leaky window air seals
Main causes: lack of electrical power, bad electronic control board, wiring failure, bad temperature sensor

Repair guides for window air conditioners

These step-by-step repair guides will help you safely fix what’s broken on your window air conditioner.

How to replace a window air conditioner ambient thermistor

If your window air conditioner isn’t cooling properly, it might need a new ambient thermistor. You can replace it yourself following these instructions.

Repair difficulty
Time required
 45 minutes or less
How to replace a window air conditioner user interface control board

Control buttons or lights on the user interface control board can stop working. This repair guide shows how to replace it.

Repair difficulty
Time required
 30 minutes or less
How to replace a window air conditioner electronic control board

The electronic control board is the brain of your window air conditioner. Here’s how to replace it.

Repair difficulty
Time required
 45 minutes or less

Articles and videos for window air conditioners

Use the advice and tips in these articles and videos to get the most out of your window air conditioner.

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How to fix a smelly room air conditioner

By Sears PartsDirect staff

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Room air conditioner installation and operation tips

By Sears PartsDirect staff

Window air conditioner installation tips.