RV air conditioner not cooling well

Symptoms

• AC runs but air isn't very cold
• AC blows air but weakly
• AC works fine on shore power but not on generator, or vice versa

Likely causes

• CommonDirty air filter restricting airflowA clogged filter reduces the volume of air moving across the cooling coil, weakening the cooling effect.
• CommonInsufficient voltage or power supplyRV AC units need a solid 110–120V supply; running on a small generator, a long/thin extension cord, or low voltage shore power reduces performance.
• PossibleDirty condenser coil on the roof unitDirt and debris on the outdoor coil reduce the unit's ability to reject heat, similar to a home AC's outdoor unit.
• Less commonLow refrigerant from a leakRV AC units are usually sealed systems, so a refrigerant leak, while less common, does happen with age.

What to do

1. Clean or replace the return air filter inside the RV, which is often easy to access and a very common cause of weak cooling.
2. Check the power source; try shore power at a different pedestal if possible, since generators or long extension cords can cause voltage drops that hurt AC performance.
3. If accessible and safe, visually inspect the rooftop unit's outdoor coil for dirt, leaves, or debris and gently clean it.
4. Make sure all windows, vents, and doors are closed while running the AC, and check that ceiling vents inside are open and not blocked by items.
5. Run only one AC at a time on a smaller generator, since running two simultaneously can starve both of adequate power.
6. If cooling remains weak after cleaning the filter and coil with adequate power confirmed, have an RV technician check refrigerant levels and the compressor.

Tools and parts

• Flashlight
• Soft brush

When to call a pro

If cooling remains poor after basic maintenance and confirmed good power, have an RV technician check refrigerant charge and compressor function.

Safety