Why Is My RV AC Dripping Water Inside?

Heating and cooling systems are among the main reasons campers upgrade from tent camping to RVing. They’re wonderful when they work, but what happens if you return after an outing and find your RV AC dripping water inside?

A towel to absorb the water or a bucket under the drip are temporary solutions. But you’ll need to troubleshoot this common RV issue to prevent it from continuing. This tutorial investigates why an RV AC drips water and how to prevent it from doing so.

Why Does My RV AC Drip Water Inside?

Ignoring a dripping RV AC poses a considerable risk of electrical damage or water damage to ceilings, floors, furniture, and personal property. Electrical and water-related issues can be dangerous and expensive to repair. So, address RV AC leaks as soon as possible.

Water dripping inside an RV from an AC is typically a sign of a larger issue, and there are several common reasons why it happens. A clogged or dirty air filter is the most common, and also the easiest to prevent with regular cleaning. This is distinct from RV water leaks overall, which are more often caused by roof or seam issues rather than issues with the AC unit.

Clogged or Dirty AC Filter

Regular inspection and cleaning of your air conditioner’s filter is arguably the most important DIY maintenance task you can complete for your RV’s cooling system. Most RVers inspect and clean their AC air filter(s) every 3-4 months. Make it part of your post-trip RV cleaning routine, and it’ll always be ready for the next trip. 

When an air conditioner filter is too dirty, airflow will be restricted. That lack of airflow, often combined with dirt buildup in the evaporator coil and fins, reduces heat transfer from the air into the coils. This causes the coils to get too cold, and any humidity in the air condenses and freezes on the coils. 

This is especially true when the AC has been running for a prolonged period, there are many people in the RV, or activities such as cooking or hot showers are taking place. However, when the AC unit cycles or you turn it off, the coils will begin to thaw, and the moisture frozen on them will drip inside your RV. 

To avoid this issue, inspect and clean your air conditioner’s filter and coils at least quarterly, if not more often. If your unit uses a more traditional residential-style air filter, keep a stock of replacement filters on hand for RV air conditioner maintenance.

Impacted Drain Pan or Line

Most RV air conditioners work by pumping heat out of your RV and simultaneously lowering the humidity level. When that moisture is drawn from the interior air, it often collects in the air conditioner’s condensation drain pan, where the evaporator coil is located. 

In most AC designs, the drain pan has a small hole that allows water to run out onto the roof, where it then runs off a side. This is normal for a camper with AC. That’s why you’ll often see an RV AC dripping water outside when running.

However, if that drain pan is clogged or damaged, or if you’ve improperly sealed your air conditioner with a sealant not recommended by the manufacturer, moisture may not drain as intended. When this happens, the drain pan can overflow, and the water will naturally find another place to drain: inside your RV. 

To check this issue, you must remove your air conditioner shroud and the inner evaporator cover to inspect the drain pan. If the drain hole is simply clogged, removing dirt and debris should remedy your issue. If the drain pan is damaged and that damage prevents proper draining, you’ll need to replace it.

Finally, if you’ve resealed around your air conditioner and that sealant prevents proper drainage, you’ll need to remove the sealant that’s affecting drainage and consult your manufacturer about the best sealant to use on your RV roof.

Technician Tip: We touch on gasket compression below, but be aware that if the AC gasket is worn out, the AC chassis can bottom out on the roof membrane, preventing condensate discharge.

How To Unclog an RV AC Condensate Drain Line

The condensate drain line is the small tube or channel that carries water from the drain pan out of the A/C unit and off your roof. Over time, dust, pollen, algae, and even small insects can clog this line, causing water to back up into the drain pan. Some manufacturers, such as Airstream, utilize drain hoses to drain the condensation out of the RV. These drain hoses can become disconnected, cracked, or plugged, allowing water to drip into the RV.

How to clear a clogged drain line:

• Turn off and unplug your AC before working on it.
• Remove the shroud to access the drain pan and locate the drain opening.
• Use a soft, flexible wire (a plastic zip tie works well) to gently clear debris from the opening. Avoid anything rigid that could puncture the line.
• Flush the line with a small amount of water to confirm it drains freely.

If water still won’t drain, or you can’t locate the clog, the blockage may be further inside the line, or the pan itself may be damaged. This is a good time to schedule a professional AC inspection.

Technician Tip: If the simple measures discussed here are not effective and the line must be removed or replaced, the hose routing will determine whether it is a DIY task or a Certified Technician-level skill. If the drain line is completely visible and readily accessible, it can be DIY’d. If it disappears into the ceiling or walls, it requires specialized tools and training.

Improper Installation

Your RV AC could also leak inside because it wasn’t installed or secured correctly. RV air conditioners have an exterior gasket that must be compressed to the manufacturer’s recommendation. Failure to tighten the unit’s lag bolts to the recommended torque setting can allow water to leak into your RV. Overtightening can also crack the roof and ceiling structure, or create a slight depression in the roof deck, both of which can funnel water into the RV.

An exterior AC gasket doesn’t last forever, either. These gaskets relax and shrink over time, so the AC mounting bolts must be snugged up to the manufacturer’s specifications regularly as part of your other seasonal maintenance tasks. Depending on environmental conditions and the type of foam the gasket is made from, they are generally good for 4-5 years, but must be replaced when they’ve lost their elasticity.

In addition to compressing the air conditioner gasket, the ceiling assembly must be properly secured to the exterior of the roof-mounted air conditioner. The shroud must be secured correctly and free of any cracks or holes allowing water in. The ceiling assembly must be properly installed and fully sealed with foam and foil tape to prevent cool and warm air from mixing, which can lead to overcooling, condensation, icing, and thus water dripping into the RV.

To evaluate potential installation issues that could be causing RV AC leaks inside, visually inspect the shroud and exterior gasket for cracks or other damage. You can also contact the AC manufacturer for their recommended lag bolt torque setting and check that after removing the ceiling assembly panel inside your RV. If the torque specs aren’t available and the 50% compression method is recommended instead, measure the thickness of the uncompressed gasket and stop tightening at half that measurement.

This tutorial on improving RV AC efficiency provides excellent information on disassembling an RV air conditioner to inspect these components and/or perform an aftermarket upgrade.

Broken Pump

Many air conditioners for RV use are equipped with a pump that moves water from the condenser unit to the condensation drain pan. If this pump fails, the air conditioner won’t drain properly, water will build up, and the drain pan will overflow, leaking water into your RV. 

In most cases, the suspicious sign of a broken pump is an audible change to the air conditioner’s noise output when operating. Listen to your air conditioner when the fan is running versus when the RV AC compressor cycles on. If your air conditioner doesn’t sound normal during operation, it’s a good sign that it’s time to have a trained technician inspect it.

Noticing a rattle or hum along with the leak? See our guide on what to do if an RV AC is making noise outside of normal operation.

How To Prevent Your RV AC From Dripping Inside Again

Once you’ve fixed the immediate leak, a few regular habits make it far less likely to come back:

• Clean your AC filter every 3-4 months if you camp occasionally, or monthly if you’re a full-time RVer. You can’t clean it too often!
• Check the exterior gasket compression annually (typically 50% compression), ideally at the start of the camping season.
• Flush the condensate drain line once a season to prevent debris from building up and causing a clog.
• Inspect the shroud for cracks after every trip, and especially after any low-clearance driving or extended storage period. On travel days, climb up for a quick peek once you reach your destination.

Technician Tip: You never know when or how damage to the plastic covers and roof deck occurs. You didn’t hear or feel anything. You didn’t think there were any low limbs. But here is some damage. It is often quick and easy to fix right away, but if left for a month could result in severe damage to the RV. This is a preventive task where being proactive is essential.

RV AC Leak FAQs

Technician Tip: Interesting fact: Up to 40% of an air conditioner’s cooling power can be lost to dehumidification!

Is It Time to Service Your RV AC?

In addition to these issues, your air conditioner could leak inside due to a damaged coil or faulty air handler. These are issues best left to a trained RV technician. 

If none of these tips solves your RV AC leak, it’s time to contact a service center to schedule an AC diagnostic. Trained technicians can quickly test and troubleshoot RV AC issues to identify the cause of a leak. They can also perform routine RV AC maintenance and alert you to upcoming services to schedule. 

Of course, you can also schedule an RV service appointment if you’re uncomfortable performing any of these troubleshooting checks at home!

If a technician informs you that your RV AC needs to be replaced, use this guide to choose the best RV air conditioner replacement.

Need help with other AC issues? See our complete guide to RV AC troubleshooting.

Have you experienced your RV AC dripping water inside? Tell us about your experience and how you fixed the issue.