Don’t Hesitate to Renovate

Be Cool The lowdown on air conditioning maintenance.

Top: Check the A/C condensation tray for corrosion and proper drainage. Bottom: Inspect raw water cooling system components for corrosion or damage.

CAPT. FRANK LANIER is an award-winning journalist, boat maintenance guru and owner of Capt F.K. Lanier & Associates, Marine Surveyors and Consultants:

CAPTFKLANIER.COM.

Most boat owners rarely give their air conditioning (A/C) systems a second thought — until they stop working. The key to keeping your air conditioner operating reliably is regular maintenance. Here’s how to keep your system cranking out cool goodness on even the hottest of summer days.

Keep it fresh A/C systems have three major components: An evaporator, where “boiling” refrigerant absorbs heat from air; a compressor, which pushes the refrigerant through the system; and a condenser, where the refrigerant is cooled prior to being returned to the evaporator. Marine A/C units are typically “direct expansion” designs, which means they pump refrigerant directly to air handlers located in the boat’s interior. Larger vessels may instead use a chilled-water system, which cools and circulates cold fresh water through the air handlers instead of refrigerant.

Marine A/C units work by exchanging heat with circulating raw water (i.e. the water your boat is floating in). When problems occur, one of the most common causes is lack of water flowing through the system. Restricted water flow can cause a lack of cool air and more frequent on/off cycling as the unit struggles to operate.

The first step in cooling water system maintenence is checking the cooling water intake strainer, which is located between the raw water intake seacock and the unit’s pump. Shut off the seacock, then remove the strainer basket and make sure it’s clear of debris and growth. Once the strainer basket is removed, open the seacock briefly to ensure nothing is clogged. The fine, stainless steel mesh baskets found in many A/C strainers can erode rapidly due to the constant water flow of water, so it’s a good idea to keep spares on hand.

Next up is checking the condition of all hose runs and connections. Begin at the seacock and work your way through the system. Look for issues such as leaks, corroded or broken hose clamps, chafe, collapsed hoses and those showing signs of age or deterioration. Raw water cooling hoses should also be double clamped if there is sufficient hose barb to allow it.

Hose failure can be particularly bad for owners who continually run the A/C while the vessel is left unattended. If a raw water-cooling hose fails with no one onboard, the continuous pumping of water can

Ensure all A/C system fi lters fi t properly and are clean.

easily sink a boat. Oxygenated seawater produced by this constant flow also encourages marine growth to take up residence and thrive in your cooling system.

Another issue that can restrict cooling water flow is the buildup of scale in the condenser coils. The coils should be flushed periodically with a weak solution of biodegradable acid to remove both scale and marine growth, typically every two to five years. Back flushing the system using dock or pressurized water is another option if the system is clogged.

Just add air In addition to cooling water, an A/C system also needs plenty of air flow. Quality, properly fitted air filters are crucial to protecting your A/C against dirt and dust. Most systems will have two filters — one behind the return air grill and one at the evaporator unit. Air filters should be cleaned monthly, typically by vacuuming, or removal and washing with plain water. Allow them to dry thoroughly before reinstallation.

Don’t forget to check the condensate pan. This is the tray below your A/C unit that collects the water (humidity) pulled from the air as it’s being cooled. The two things to look for here are proper drainage and corrosion of the pan itself.

The pan should be plumbed so that it drains overboard or into a sump, where the water is then pumped overboard. Allowing condensate to drain into the bilge is not recommended. A simple way to check the drain for proper operation is to temporarily plug the drain and pour water into the pan, which should then drain away within 30 seconds or so of being unplugged.

If the drain hose is clogged, it can be blown clear with compressed air or pressurized water. If the pan is corroded, particularly to the point it can no longer contain the condensation, it should be repaired or replaced.

Maintenance requirements for a chilled water A/C system are similar to those for a direct-expansion system. Chill water systems have to be filled with water to operate properly (similar to refrigerant in a direct expansion system). They will typically have pressure gauges, allowing you to check for leaks or air in the system, which should be part of your regularly scheduled maintenance. With a little bit of elbow grease it’s easy to keep cool. ★