stream In the case of a molding, use care not to crack it when removing it. 4 0 obj Once the temperature reaches a preset level, the defrost thermostat opens, shutting off electric current to the defroster heating elements, much as your home's heating thermostat shuts down the furnace once the home reaches the preset room temperature. To remove the plates, remove the screws or release the clips with a small screwdriver. The duration of the heat cycle is controlled by the timer. 12 0 obj If the unit is undersized for the space it is not faulty. Privacy Policy << Which is the Best Air Conditioner for Me? Temperzone Ltd © Copyright 2020 << x��w\G�ǣƚ��c�O)�%K�����̓�����hL��$6�"*��@�-*�� M� Function HBDF measures the build-up of ice between the fins of the evaporator. In side-by-side refrigerator-freezers, the thermostat usually is at the back of the compartment. A malfunctioning thermostat can keep the defrost heating elements from turning on or keep them on too long, causing heat damage or even a fire. %PDF-1.5 A sensor detects the formation of ice, triggers a switch which turns off the compressor and the evaporator is no longer cooled. Attach the test probes to the terminals on the thermostat. Pull the defrost thermostat free of its retainer clip and remove the electrical wires from its terminal. In heating mode a heat pump extracts heat from the outside air and transfers it inside your premises to warm it. <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> When the ambient temperature outside gets very cold (close to 0°C or below) the moisture in the air freezes on the outdoor unit’s heat exchanger as the fan blows the air across it. endobj While most people are familiar the general concept of auto-defrost, few people know how the system works. Often this has not been explained well before installation, which leads to a lot of confusion about why the heat pump is not working. If the thermostat does not display an “0.000” when cold or an “O.L.” when hot, the thermostat is bad and needs to be replaced. Based in Colorado Springs, Colo., Jerry Walch has been writing articles for the DIY market since 1974. Keep your unit well maintained (as above) and ensure you are operating it correctly. <> Often this has not been explained well before installation, which leads to a lot of confusion about why the heat pump is not working. <> How often will my unit go in to defrost mode? It is important not to stop the unit before the defrost cycle has ended, because if the unit is restarted shortly afterwards it will run very inefficiently and may cause damage to itself. Refrigerators and freezers are designed to … If this doesn’t remedy the problem you should consult your installer or another reputable heat pump installer. The fan continues to run so that the flow of air from the room can pass over the evaporator and assist with the thawing process. Some of these include: There are timers built in to the computer control of the unit that restrict how often defrosting can occur. Set the function selector switch on the digital multimeter to its R x 1 scale. More immediately, keeping doors closed and curtains drawn will also help to reduce your heating required. %���� endobj Known as auto-defrost or self-defrosting, this feature is essential for controlling the frost inside refrigerators and freezers. Historical Advertising Video competition entries, The amount of heating load the unit is trying to deliver. In extreme cases this can also cause damage to the outdoor unit. endobj Of course the less load you place on the unit the less frequently it will need to defrost in cold conditions. If this doesn’t remedy the problem you should consult your installer or another reputable heat pump installer. A defrost cycle is simply the system recognising that ice has formed or begun to form and automatically fixing this. How to Check a Defrost Thermostat. Either of two factors can bring the unit out of a defrost cycle. With bottom-mounted freezers, the thermostat usually is under the compartment's roof plate. Generally a unit must run for a minimum of around 35 minutes after starting up before completing its first defrost. Initially you should consult your instruction manual to ensure you are operating the unit correctly. 8 0 obj endobj endobj Is there any way I can help to reduce defrosting? This action is not triggered by the frost itself, but rather by the freezer temperature. 1 0 obj endobj <> There are a number of factors that influence how often a unit will go in to defrost mode. endobj Locate and access the defrost thermostat. Depending on the ice build-up, the sensor emits up to 20 mA. <> Secondly, if the sensors do not stop it beforehand, the maximum time a unit will be in defrost cycle is around 10 minutes. If the unit has operated like this since it was first installed (first cold snap), you may be operating it incorrectly or it may be undersized for the space it is trying to heat. Outside, the outdoor fan will also have stopped and the compressor will be running. 2 0 obj His work has appeared in “Family Handyman” magazine, “Popular Science,” "Popular Mechanics," “Handy” and other publications. endobj They can assist you to ensure correct operation, and correct sizing. endstream 11 0 obj Firstly, if the sensors on the outdoor unit detect that it’s heat exchanger temperature has risen enough, the unit will stop defrosting. Ultimately permanent fixes such as installing insulation in ceilings, walls and under floors will help reduce your heating requirement (and ultimately save you money). © Copyright 2020 Hearst Communications, Inc. 7 0 obj The LCD on the meter will display “0.000” if the cold thermostat is in the closed position. endobj A recently developed problem may be an indication of a fault or maintenance required. endobj Why does my unit have to do a defrost cycle? Regular defrosting, or a lack of heat could be caused by a number of factors. The defrost thermostat, a bi-metallic switch, controls the temperature rise in the freezer compartment during the defrost cycle. This will help a lot. This document is provided to help users understand the defrosting cycle and address any concerns. The sensor is installed and calibrated for the currently installed evaporator. 3 0 obj [ 9 0 R] <> The defrost cycle ends when the temperature sensor at the outdoor coil senses the temperature of the coil at about 75 ° F or when the circuit board's timer overrides the sensor. When the evaporator is free of ice, the sensor emits 4mA. How to Replace a Bulb for Frigidaire Ice Maker in a Door, How to Check the Defrost Timer on a Side-by-Side Kenmore, How to Troubleshoot Fuses on a Kenmore Front Loading Dryer, Troubleshooting a Doorbell That Doesn't Work, How to Check the Continuity on a Water Heater Element, Acme How To: How To Test the Defrost Thermostat, PartSelect: How to test a refrigerator defrost thermostat, Refrigerator Defrost Problem Diagnostics, How to Open a Refrigerator Evaporator Cover, How to Replace the Thermal Fuse on an Amana Gas Dryer. When the thermostat opens, the meter's LCD will display an “O.L.,” indicating no continuity through the bi-metallic switch contacts inside the defrost thermostat. In most cases, the wires are connected with push-on terminals. Understanding Defrost Cycle . <> During winter months many heat pumps will need to go through a “defrost” cycle during operation. The defrost thermostat should be in the closed position when cold. Walch spent 40 years working in the electrical trades and holds an Associate of Applied Science in applied electrical engineering technology from Alvin Junior College. 5 0 obj exclusive New Zealand distributors ofHitachi Air Conditioning. Plug the black test lead into the black jack marked "COM." Working in conjunction with a timer the defrost thermostat controls the heater which turns on briefly when the bi-metal strip closes the circuit. stream The plates covering the thermostat may be held in place by screws or clips. <>>> The responsibility for correctly sizing the unit initially rests with the installing company – they will need to remedy the situation if the unit is too small. 9 0 obj The defrost thermostat, a bi-metallic switch, controls the temperature rise in the freezer compartment during the defrost cycle. 6 0 obj Yes there certainly is. <> Plug the red test lead into the red jack, marked "VmA" -- volts milliamperes. Check to be sure the thermostat is opening at the correct temperature by placing it in water and slowly heating the water. Move the refrigerator away from the wall and unplug the power cord from the wall receptacle.