Walk-In Evaporator Dripping or Spitting Water

When water comes out of the front of the evaporator, sprayed across the box or dripping from the fan guards, the drain line is usually not the first place to look. Something is moving water off the coil before it can reach the drain pan, or pushing it back out of a pan that is already full. The timing of the spitting is the best clue.

If the water is only on the floor directly under the unit and nothing is being blown out, start at walk-in cooler leaking water instead.

Watch when it happens

Spend a few minutes near the evaporator around a scheduled defrost, and at a random time of day. Note:

• Does the spitting start right when the fans restart after a defrost?
• Does it happen at random times during normal cooling?
• Is it coming from one fan, or all of them?
• Is there ice on the coil, the fan blades or the guards?

What's usually behind it

Fan delay and refreeze

This is the most common cause in freezers. After an electric defrost, the coil is covered in water. The control sequence is supposed to let it drain, then chill the coil back below freezing with the fans still off, so leftover droplets freeze in place rather than being blown into the room. Only then do the fans restart.

Heatcraft's Beacon II controller describes this sequence: after electric defrost, a two-minute drain-down, then refreeze until suction reaches 28°F or three minutes pass, with fans held off. Older systems use a fan delay switch (a small thermostat on the coil, sometimes called a klixon) to keep the fans off until the coil is cold.

If the delay switch fails closed, the probe is misplaced, or the setting is wrong, the fans come on while the coil is still wet and spray water forward. In a freezer that water freezes on the ceiling, the product and the shelving in a fan-shaped pattern in front of the unit. See ice buildup in a walk-in freezer for what that looks like over time, and the defrost system page for the controls.

Defrost that ends too early

Defrost is supposed to end when the coil reaches its termination temperature (Beacon II defaults are 60°F for electric defrost and 45°F for air defrost) or at a fail-safe time if it never gets there. If the termination sensor reads warm too soon, or defrost is ending on the fail-safe because the heaters are weak, the coil can still carry patches of ice and slush when cooling resumes. The fans then blow meltwater and slush off the partially cleared coil.

Some controllers track this. Heatcraft's intelliGen shows IN05, "Too Few Defrosts," after eight time-terminated defrosts in a row, which suggests defrost isn't finishing on temperature.

A pan that can't drain

If the drain line is clogged or frozen, the pan fills during defrost and stays full. Once the fans run, air moving across the full pan and the bottom of the coil picks up water and throws it out. In freezers that pan water may freeze and build up into the coil, which makes things worse each cycle. Heatcraft lists ice in the pan as a sign of a defective heater, bad pitch, a plugged drain or a failed drain-line heater. The fix is on the drain side; see drain line heater.

Level and mounting

The drain pan slopes toward its outlet only if the unit hangs level. When one end sits lower, from loose hangers, a sagging ceiling panel or an original install that was off, water pools at that end, and the fan over it lifts water out of the pan. The clue is spitting from one fan only, at the low end, while the drain itself runs clear.

Ice on fans and a melting coil

An evaporator fan blade that picks up ice becomes unbalanced. It vibrates and rattles, and as the ice melts during defrost or cooling it flings water outward. The fan guard itself can also collect ice that drips. Ice on the blades usually traces back to water being thrown during the previous restart, or to air leaking in near the unit. See evaporator fan motor.

A coil that was blocked with ice and is now thawing, after a repair or a manual defrost, sheds a lot of water at once. Some will overflow the pan and some will be blown out. That's temporary if the cause of the ice was fixed. See evaporator coil frozen.

Water carried off in coolers

In coolers, which usually use air defrost with the fans running, spitting right after defrost is less common. Fine droplets on product in front of the unit during normal cooling can mean the coil is wetter than it should be, from high humidity or heavy door traffic, and airflow is carrying condensate off the fins. A coil that is dirty or partly blocked can make it worse by forcing air through fewer, faster paths.

Checks staff can do safely

1. Note the timing of the spitting relative to defrost and write it down.
2. Look at the coil and fan blades with a flashlight for ice, slush or standing water in the pan. Don't reach into the unit.
3. See whether the unit looks level, or whether water collects and drips at one end.
4. Move product out of the spray zone and cover what can't be moved.
5. Dry the floor and mark it; in a freezer, clear ice with plastic tools only.
6. Note any controller messages about defrost.

Safety: Keep hands, tools and cleaning cloths away from the fan guards. Fans can start without warning at the end of a defrost. Don't chip ice from blades or the coil.

What a technician will check

• The full defrost sequence: start, heaters, termination temperature, drain-down, refreeze and fan restart.
• The fan delay switch or controller fan-delay setting, and the coil sensor location.
• Defrost heater amperage, if defrost ends on fail-safe.
• Drain pan heater, drain line and trap.
• Unit level and hanger condition.
• Fan motor type, speed and blade against the manufacturer's specification.

For how the whole unit cooler fits together, see evaporator coil, and for Heatcraft units specifically, the site's Heatcraft troubleshooting guide.