Food Equipment Maintenance

Here is a look at problems that affect refrigerated foodservice equipment:

Unit is not running: First check power to the unit, as well as fuses or breakers. Make sure the unit is on a dedicated circuit and that no extension cord is being used. Measure voltage and compare to rated line voltage. Check for burnt or loose electrical connections.

Check that the control temperature setting on the unit is calling for cooling. Check the timer to see if the unit is in defrost mode. Manually check that all safety switches and pressure switches are operational.

Check the condition of the coils and filters. Dirty filters are common in foodservice installations, and can lead to a number of problems.

If the compressor doesn't start when power is applied, check the start capacitor. If a relay is used to start the compressor, check to see that the relay is operating properly. If the system checks out OK electrically, the compressor might have failed and would need to be replaced.

Unit is running non-stop: Check the condenser coil and the cleanliness of the air filter. Air flow problems can reduce the effective capacity of the refrigeration system. Check doors and seals.

If the evaporator coil is iced up, this indicates that the defrost cycle might not be working or more frequent defrosts are required. Four to six defrost cycles per day is usually adequate. Check to see if defrost is accomplished with heater or hot-gas defrost. Force a defrost cycle to check power and heat on heaters. In hot-gas defrost units, make sure that the solenoid valve opens at the start of the defrost cycle to redirect hot gas to the evaporator.

Refrigerant leaks can also lower system capacity, causing long run times.

Unit is short cycling: This problem is usually caused by a protection device in the system. An overload protector, a thermostat, an oil level protection device, or a pressure switch might be taking the refrigeration system off-line.

Improper refrigerant charge can lead to short cycling. Overcharge can cause the pressure switch to trip, while undercharge can cause the oil safety to trip. A defective run capacitor can cause the compressor to trip.

Once the compressor starts, check the amp draw of the compressor to verify proper operation.

Unit is not holding temperature: Many service engineers jump to the conclusion that there is a refrigerant leak. Before assuming this, make sure that the evaporator fan is running. Verify current draws on all major components. Check the door and seals. Again, a clogged condenser coil can cause multiple problems. As a last resort, add pressure taps and verify operating pressures. A deep vacuum implies a loss of charge. Leak check the system.

Unit is noisy: Noise often indicates that a mechanical component is ready to fail. Since the unit is running, this in an opportunity for the service engineer to diagnose and correct the problem before the unit fails. Check for loose parts that might rattle or come in contact with other components. Check for unusual noise and vibration from compressor and motors. The bearings in the fan motor can become noisy when the fan is getting ready to fail.

Whatever the cause of the problem turns out to be, systematic troubleshooting is the best way to identify the root problem and fix it right. If components need to be replaced, root cause analysis is the best way to get the unit back up and running for the operator. Whenever possible, utilize components and a procedure that will provide the user an extra level of protection.

If the cause of the problem was a refrigerant leak, the service engineer must determine where the leak occurred. If the leak occurred on the high pressure side of the system, then repair the leak, replace the drier, evacuate and recharge the unit, and put it back into service. If the leak occurred on the low side, also change the compressor as moisture may have been sucked into the system and the oil.

Filter Driers

The newer refrigerants and POE Oils introduced to meet industry standards work under a much more precise operating environment-one that must be essentially free of moisture and contamination. Excessive moisture and contamination levels can quickly lead to variations in the refrigerated setting. The right filter drier is essential for reliable, long-lasting system protection.

Emerson Climate Technologies manufactures a filter drier that is optimized for foodservice refrigeration systems with capillary tubes. The EK SV CAP filter drier provides:

• Measurably superior filtration of contaminants
• Drying of the refrigerant
• Removal of acids

This superior combination of filtration and moisture and acid removal provides better protection for the compressor and capillary tube versus any other filter drier on the market.

The EK-SV Cap Filter Drier is buffered by an initial 40-micron fiberglass filter to remove most of the solid contaminants and sludge, and a 20-micron final filter to remove any remaining contamination. This ensures that the refrigeration system will stay cleaner, longer than ever before, with a minimal pressure drop in the filter drier.

The difference is that synthetic polyol ester (POE) oils are protected from contaminants by the unique beaded desiccant. POE oils absorb up to 20 times more moisture than ordinary mineral oils. That's why the EK Filter Drier is designed to quickly absorb and remove any moisture before harmful acids can form. This means your cap tubes are less likely to clog, and your compressor will have better lubrication, even in a retrofit application.

The EK-SV Cap is the easiest filter drier to install, since the outlet is designed to accept the capillary tubing without the need for crimping down the outlet fitting and then sealing the entire fitting with a lot of braze alloy. This saves you time and also results in fewer capillary tube blockages due to braze alloy entering the capillary tube.

A Shraeder Valve on the inlet side acts as a maintenance and charging port. The operational flexibility means that you can count on the filter drier for the most complex applications.

Hermetic Moisture Indicator

Moisture indicators on foodservice equipment are critical early-warning components in the fight to cut the long-term effects of water damage and reduce repair and maintenance costs. The proper moisture indicator must sense and report just how much water is in the system's circulating refrigerant. An indicator in a sight glass changes color as the moisture content reaches potentially damaging levels. Be sure to choose an indictor that does more than just say "dry" or "wet". The best moisture indicators are sensitive enough to alert operators early on that moisture levels are rising, allowing corrective action to be taken.

The HMI hermetic moisture indicators from Emerson are able to read moisture levels at levels far below industry standards. The HMI actually begins to change color at 2% RH, which is a "very dry" indication. At 3% RH, the purple caution color begins to appear. Many other indicators do not even begin changing colors until about 7% to 8% RH. However, early detection is critical with HFC refrigerants and POE lubricants. POE oil can hold up to 20 times more moisture than the mineral oil used by older refrigerants, which can allow corrosive acids to build up and totally destroy a system.

The HMI is the only sight glass on the market that is UL-listed with a 680 psig maximum working pressure, making it acceptable for use with higher pressure HFC refrigerants. Also, it has a larger viewing window for easier visibility and charging. It is resistant to "wash out" from water and can withstand brazing temperatures up to 450 degrees F. The fully hermetic design includes a corrosion-resistant, all brass body with no o-rings or knife seals that are likely to leak. The indicator also features solid copper fittings for easy, universal replacement.

Operators should understand that periodic preventative maintenance is the best way to keep equipment up and running efficiently. Service engineers should prescribe a routine maintenance schedule with the food service operator. There are a few simple actions that the operator can take which will reduce costs and increase the life span of the equipment.

A properly maintained refrigerated unit should have a clean condenser coil and filter. The most important thing that anyone can do to maximize the life of a freezer is to regularly clean the condenser coil. When a condenser coil becomes clogged with dirt and dust, it reduces the air flow across the fins, reducing heat transfer and driving up the discharge pressure. This makes the compressor work harder, wastes energy, and can actually raise the temperature in the freezer. The condenser coil should be cleaned every month.

To clean the condenser coil, brush and vacuum any dirt or dust from the surface of the coil. Be careful of the sharp fins, and do not bend or push in any of the condenser fins. If there is a filter, it should be cleaned with warm water and mild detergent, or replaced. In areas around cooking equipment, grease may collect on the coil and will have to be removed with a commercial coil cleaner. Care should be taken that the cleaner used is approved for use around foods and is compatible with the coil materials.

Food and contaminated can fall into the evaporator coil and drain pan. Because these areas come in contact with food, they should only be cleaned according to the manufacturer's recommendations. Any cleaner or sanitizer used should be approved for use around foods.

Door gaskets can be cleaned with a brush and mild soap and hot water. This will help reduce air leakage by ensuring a proper seal, and will extend the life of the gasket. Also make sure that the door is closing tightly.

To keep your customers satisfied, you must deliver the best technology, the best service, and the best protection. And with Emerson Climate Technologies™ you can deliver every time.

Contractors around the world have turned to Emerson for the ultimate refrigeration solutions, all reinforced by unwavering customer support. And with breakthrough products like the EK Filter Drier and Hermetic Moisture Indicator, your customers' refrigeration systems will have a higher level of protection.

The EK Filter Drier and all the essential Emerson Climate Technologies products are conveniently available at wholesalers worldwide. For information on local refrigeration wholesalers near you, go to EmersonClimateContractor.com.

EK Filter Drier

HMI Hermetic Moisture Indicators

Emerson Climate Technologies