Ice machines can occasionally get less respect than they deserve when it comes to service. Granted, they're usually not the biggest or most expensive pieces of equipment in a building, but proper maintenance is important to prevent downtime, increase efficiency, and reduce your customer's cost of ownership.
The first step in a good ice machine service call is to perform a complete visual inspection of the machine and its bin/dispenser. Think about everyone's safety and look for potential hazards or slip and fall issues. Look under the bin to see if the legs or casters are damaged. This can happen on machines that are frequently moved.
Drains are a commonly overlooked area of maintenance. They're often not being blown out and cleaned properly. Many technicians clear the drain from the machine, but fail to check the termination of the drain line. Pour water down the dispenser drain to make sure it flows away quickly. If it doesn't, the drain may need to be cleaned or repaired. Follow the drain to its termination to ensure that it’s clean and pitched correctly, and make sure the drain line termination conforms to local code.
If the ice machine is in a restaurant that uses yeast, be aware that the yeast in the air often gets into the drains. If they're not cleaned out carefully they can plug up quickly.
As you perform your service, think about how to save the owner money. Clearance issues are common. If the ice machine is tucked away in a small, enclosed space, that may mean high head pressure and high cost of operation. Or, if a self-contained, air-cooled ice machine is in a conditioned space, inform the customer that the space's air conditioner must remove the heat rejected from the ice machine. A1,000 lb. self-contained ice machine, for example, puts a 16,000 Btuh load on the air conditioning system. As a possible solution to this, the customer may be interested in a remote condenser.
In cases where the unit is already served by a remote condensing unit, follow the refrigerant lineset to the roof. Make sure the insulation is intact and none of the lines have been kinked. This type of damage is especially prevalent when the lineset runs through spaces that are used for storage.
Remove the outer panels and inspect the interior of the ice machine and bin/dispenser. Look for any indication of mineral buildup, mildew, slime mold, or rusting.
Open the electrical junction box and ensure that the wire is correctly sized for the machine. Undersized wires will decrease equipment life, increase operating costs, and result in service calls. Check all other connections and wire nuts to make sure they are secure and show no signs of overheating. Use a mirror to inspect the contacts on the contactor – debris under the contacts can lead to arcing, high operating costs, and premature failure.
Use a flashlight to check the condenser coil. Check the entire evaporator and all corners and outer edges. Vacuum or blow the coil out thoroughly; you must be able to see light throughout the entire coil. Don't forget to stick your head below the condenser coil on a remote condenser. Airflow moves from bottom to top.
Normally, you wouldn't use a foaming coil cleaner to clean an ice machine coil: it's indoors and you’d just make a big mess. However, in kitchens where a coil is grease-covered, it may be the only way to go. Location has much to do with your task here. If the ice machine is next to a deep fryer, it's likely to get grease splattered on it. There’s a pizza franchise I know of, where the kitchen layout calls for the ice machine to be placed next to the dough mixer. So, every time they pour flour into the mixer, some of it finds it way into the ice machine condenser. As soon as that flour has a little humidity to work with, it forms a sticky goo that's extremely difficult to remove.
Clean the Evaporator
Dry the evaporator and inspect it for deposits. Use a nylon bristle scrub brush to clean dirty evaporators and extrusions on neglected machines.
Remember that ice is food. Ice machine cleaner removes mineral deposits and lime scale, but it doesn't disinfect. Make sure to use sanitizer on the ice machine and bin/dispenser to ensure the ice is safe to consume. Dispensers can be hard to reach, but it pays to make sure they’re clean and free from deposits and scale. After your inspection and cleaning, spray the dispenser thoroughly with sanitizer.
Install or replace water filters to prevent mineral buildup. Educate your customers that the purest water freezes first, which means filtered water equals the fastest freeze and harvest cycles. This saves money.
Verify Correct Operation
Check to see if water is wicking/spraying/leaking from the evaporator or water trough into the bin or dispenser, or if supply water is escaping down the drain. Ensure that water flows evenly across the entire surface of all evaporators.
Time a freeze/harvest cycle and verify that it matches the manufacturer's published cycle times. Production and efficiency are seriously reduced when the freeze cycle is longer or shorter than the design specification. Weigh the ice produced in one cycle and compare it to the published quantity. Adjust it until the ice production and freeze/harvest times match the published production amount. If the freeze cycle is too long, and the operational sequence, water flow and adjustments are correct, the problem is usually a refrigeration issue. Refer to the manufacturer's website to obtain the latest diagnostic information for the model you are repairing. If you have a printed version of the manual, use the manufacturer’s website periodically to verify it is the latest revision.
If the harvest cycle is too long, the likely culprits are build-up on the evaporator or a mechanical defect. The first step is to determine if it's a physical evaporator issue or a refrigeration issue. At the end of the harvest cycle, turn off the ice machine and inspect the side of the cubes that were in contact with the evaporator. If the cubes are melted and misshapen, the issue is a mechanical issue. Inspect the evaporator and the extrusions that mount the evaporator to the ice machine. A thorough inspection will reveal the cause in all but the most unusual failures. If the cubes cannot be removed by pulling with your fingernails and are not melted or misshapen, the issue is a refrigeration problem.
When correcting an ice machine refrigeration problem, obtain your refrigerant pressure readings with individual "stub" gauges, not long-hosed manifold gauge sets that remove or add refrigerant charge.
Remove any ice on the evaporator(s) and observe operation throughout an entire freeze and harvest cycle. The diagnostics vary by manufacturer, and you must have access to information that will let you know what's normal.
Don't overlook the possibility that someone else may have been careless or uninformed when servicing the equipment previously. Be aware of the location of check valves on remote condenser models to prevent trapping refrigerant or air in the system accidentally. Keep in mind that air trapped in the system from an incomplete evacuation or an under- or over-charge of refrigerant may not generate a service call until the ambient temperature increases or decreases.
Overall, ice machine service is pretty straightforward, and it doesn't vary a lot from other pieces of HVAC or refrigeration equipment. That's why, like other equipment, maintenance agreements are the way to go. Customers must do their part with preventive maintenance. Educate them on the value of regular maintenance through a contract. It's in your customers' — and their ice machines' — best interests.
Mitch Rens is the service publications manager, Manitowoc Foodservice, Manitowoc, WI. Manitowoc's Technical Service Staff can be contacted by calling 800/545-5720 or by e-mail at [email protected]
Service Clinic Extra:
Cleaning Condensor Coils
If the condenser coil is covered with grease, grim or dirt, use a non-corrosive cleaner and rinse thoroughly with water. You may find it necessary to use a fin comb or brush on the coil fins.
This is especially important on remote condenser units where the coil is subjected to outside elements. For water cooled condenser units, the water connections of the condenser coil must be disconnected and cleaning solution circulated through the coil. The water regulating valve must be cleaned and re-adjusted for proper flow once the cleaning process is completed. Service or change the filter cartridge on the external water filter/treatment system, if present. Also, inspect the control box and electrical components for loose or burnt connections. Look over the refrigeration system and service access valves for oil spots or other evidence of leaks. A good visual inspection of the unit can point to future problems. This will allow you time to correct the problem before expensive down time occurs.
— Danny Moore, Director of Technical Support for Hoshizaki America, Inc.