How To Fix a Leaking Evaporative (Swamp) Cooler

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You may be able to troubleshoot and fix your leaking swamp cooler.
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Evaporative swamp coolers are an energy efficient way to cool a house in dry climates. Unfortunately, as with most household appliance, things can go wrong. Unless the evaporative cooler has been physically damaged, there are only six places that it can be leaking from. Here are some simple ideas on how to diagnose and fix your leaking swamp cooler.


Step 1: Turn Off the Power

Before you begin, turn off the swam cooler and either unplug it or turn it off at the breaker box. Also put on safety goggles, long sleeves and gloves to protect your eyes and hands from debris.

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Step 2: Look at the Water Line

Check the water feed line. A common leak encountered on evaporative coolers is at the point where the 1/4-inch copper water line enters the cooler housing. The three most likely problems here are:


  1. The compression nut needs tightening.
  2. The rubber gasket (washer) needs to be replaced.
  3. The float valve inside has broken or come loose and needs to be tightened or replaced.

Step 3: Inspect the Float Valve Inlet

Inspect the float valve inlet. If the water leak seems to be coming from the water inlet at the float valve, the problem could be that the water entering your reservoir is spraying outside of the reservoir. Lift up on the float arm to determine if all of the water spraying out sprays into the water reservoir. If not, simply adjust the float valve to point further away from the edge of your reservoir.


Step 4: Adjust the Float Arm

Check to see if the reservoir's water level is above the top of the overflow pipe. If so, simply bend the float arm to adjust the water level.

Step 5: Check the Pads

Check the front of the cooler at the pad. This common problem results in serious damage to the front screen cover of the cooler as rust and scale buildup slowly destroys it. This type of leak will usually be the result of one of three problems. In general, repairs involve replacing either the pad itself or the distributor housing.


  1. The top of the pad is so caked with scale that the water sprays off of it.
  2. The front of the pad is so caked with scale that mini-stalactites have formed a bridge between the pad and the front screen of the cooler, which will allow water to run freely out of the front of the cooler.
  3. The distributor housing is warped and no longer forms a snug fit over the top of the cooler pad, which will allow the water to spray or squirt out.


Step 6: Inspect the Drain Hole

Inspect the drain hole on the bottom of the cooler for leaks. If you see water leaking, check to see that the overflow pipe is screwed securely into place in the drain hole. Tighten the overflow pipe. If that doesn't work, you may need to replace the drain fittings and/or the overflow pipe.


Step 7: Look for Scale Buildup

Check to see if there is leaking out of the bottom of the cooler housing from the sides of the pad. If this is the case, check the level of scale buildup on the sides of the pad and on the plastic inserts on the sides. If it seems excessive, you need to either clean or replace the pad. If the level of scale buildup doesn't seem excessive, check to make sure that the plastic side wall of the reservoir assembly is seated properly, with the base inside the wall of the lower reservoir.


Step 8: Inspect the Reservoir

Inspect the area at the bottom of the cooler housing from under the water reservoir. Attempt to tighten or even replace the drain fitting as this will be your most inexpensive possibility for a solution. Make sure the water isn't overflowing the front or back of the reservoir, if so simply adjust the float valve. More than likely, your plastic reservoir liner is cracked and needs to be replaced.


Step 9: Replace the Reservoir Liner

Turn off the water. Remove the drain assembly and overflow pipe. Remove the pad, water distributor (this can be set on top of the cooler), and the water pump (this can remain hooked up to the distributor). Unscrew the float valve from the side of the cooler.

Remove both plastic side walls as well as the brace at the bottom which seats the pad in place. Take out the large plastic reservoir liner which holds all of the systems water and replace. The plastic side walls may also need replacement.


Step 10: Repair a Metal Reservoir Pan

Drain the metal pan on an older evaporative cooler. Scrub off the rust. Patch any holes before painting inside and out with a rust resistant paint and/or sealant. Allow to dry completely before turning the water and power on.



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