A digital or analog multimeter is used to test capacitors. There are two types of capacitors used in window AC units — run capacitors and start capacitors. Some manufacturers combine both the run and start capacitors in one unit. The start capacitor provides the extra starting torque needed by the compressor to start under-load and is connected only during the start-up cycle. The run capacitor, on the other hand, remains connected at all time and serves to increase the efficiency of the compressor evaporator/condenser fan motors. Testing these capacitors is an easy process that even a beginner can do correctly and safely the first time. Unplug the window air conditioner from its dedicated wall receptacle. Remove the unit from its window mounting and place on the floor or a sturdy table. Some of these units can be quite heavy so you may want to enlist the aid of a helper. Remove the screws holding the sheet metal, wrap-around cover in place. Use caution when sliding the cover off. The edges of the sheet metal are very sharp and can cut your hands.

Replace the the screws in the frame for safe keeping. Locate the run and start capacitors. Run capacitors are oil-filled capacitors while start capacitors are electrolytic capacitor; run capacitors are round or oval shaped, silver-colored metal cans, while start capacitors are round, tubular-shaped, black-colored units. These capacitors, as a rule, are located on or very near the component they serve i.e. compressor or fan motor. Discharge the capacitor by shorting its terminals together using the metal shank of a screwdriver. Place the metal shank of a screwdriver with a plastic handle between the terminals connecting them together. Keep your fingers away from the metal shaft while discharging the capacitor. A capacitor in good condition can hold an electrical charge for several hours, even months, after the unit is unplugged from the power source. Remember, electricity is dangerous, and a shock from one of these capacitor can kill you. Take a picture of how the wires are connected to the capacitor with a digital camera, or make a sketch of the connections.

Remove the wires from the capacitor by pulling the female terminals from the male terminals on the capacitor using the long-nosed pliers. Remove the wires from the capacitor and short the terminals together again with the metal shank of the screwdriver to make sure no residual charge remains on the capacitor. A residual charge is a minute charge that will affect the test but is not a danger to humans. Set the function switch on your digital multimeter to it capacitor test position and touch the meters test probes to the capacitors terminals. The meter's LCD should display the capacitor's actual capacity in Microfarad. Most capacitors have an allowable tolerance of ±10 percent. If the reading falls within this range, the capacitor is good. The rated capacity is marked on the capacitor's case. Reverse the meter probes and repeat the test. If the reading varies more than 10 percent of the rated value, replace the capacitor. Remove the capacitor from the circuit and remove the bleeder resistor from across the capacitors terminals to prevent a false test result.

An analog meter will read the resistor's resistance and will make a good capacitor appear to have a high resistant internal short. ac units for a roomSet the meter's function switch to the “R X 1000” scale. ac outside unit not runningTouch the meter's test probes to the capacitor's terminals. cheap ac units windowWatch the meter's pointer. The pointer will quickly snap all the way over to the right and the slowly drift back over to the left for a good capacitor. Reverse the meter probes and test again. A meter reading of infinite resistance, the pointer remaining at the left of the scale, indicate an open circuited capacitor and it needs to be replaced. A constant meter reading of zero resistance, the pointer snapping to the right and remaining there, indicates a shorted capacitor and you need to replace.

Things You Will Need Phillips screwdriver Flat-blade screwdriver Long-nose pliers Digital multimeter with capacitor test function or analog multimeter References Capacitor For Motor: Test Capacitor Photo Credits Polka Dot Images/Polka Dot/Getty Images Suggest a Correction Click Here To Have A Part Looked Up. Window Air Conditioner / Window AC Trouble Diagnosis Chart Is there anything I need to do to my window AC before I start it for the summer? Yes, Check and make sure the condenser and evaporator coilsYou can use a garden hose to wash them out. it and remove it from the window to do this. Also take special care not to get the switches and the fan motor wet. Be sure to let everything dry out before plugging it back in. Also oiling the fan motor if it has oil ports is required. Note: not all fan motors have oil ports. Some are sealed from the factory and cannot be oiled. Check/Clean the Air Filter. Oil Ports on the Fan Motor

Zoom Spout Fan Oiler Great for oiling the fan motor Email our parts dept. for zoom spout oilers Great for straightening out those bent fins dept. for fin comb kits How do I oil the fan? Remove the oil port caps, some are plastic, some are metal. few drops of oil. The oil is a light weight turbine type oil. How do I check the compressor? Using a ohm meter, and the compressor is cool to the touch, and the ac is unplugged, Disconnect the wiring to the compressor and mark where the wires went. Ohm out the terminals from common to start andYou should have continuity across both. Check from each terminal, (with the wires disconnected) to ground or a piece of tubing coming out of the compressor. You should have no continuity. you have continuity to ground the compressor is shorted to ground and will If the compressor has failed and the A/C  compressor is not under warranty, then it's probably not worth repairing as compressors go for

How do I check the overload? With it disconnected check it for continuity. A/C wont come on Check the house fuses or the house breaker. Check the selector switch. Air for the unit does not feel cold enough Fan selector set to "Fan Only" position Thermostat set at too warm a setting Exhaust vent control set at "Open" position. Thermostat Sensing bulb not properly located Unit low on refrigerant Air Conditioner cooling but room too warm Air directional louvers improperly positioned Init front is blocked by draperies, furniture, etc. Outside louvers blocked by bricks, siding etc. Insufficient cooling capacity for room size Improper installation - Make sure unit is slightly tipped towards Blockage in drain - clean drain - remove unit from the window - disconnect power and wash out with garden hose - let dry thoroughly before re- applying power. Water dripping outside at the back of the unit

Unit operating in a humid environment - Normal operation Water hitting condenser fan blade.Most window ac's have what they call a slinger ringIt's a ring that runs around the outer edge of the condenser fan blade and slings water up on the condenser coil to help it cool I drilled holes in the bottom of my air conditioner to make it drain and cool better You should not drill holes in the ac base. Most window ac's have what they call a slinger ring . It's a ring that runs around the outer edge of the condenser fan blade and slings water up on the condenser coil to help it cool better. If you drill holes in the bottom , then the a/c will not hold enough water to sling up on the coil. How big of an AC do I need to cool my space? We recommend 1 Ton, (12,000 BTU) for each 500 sq. ft in a normal house and 1 Ton, (12,000 BTU) for each 400 sq. ft in a manufactured The coil on the front of the AC keeps freezing up or thermostat not cycling properly

A sign of low on charge is part of the coil frosting or freezing up and the unit not cooling well. What type of refrigerant do window AC's use? Most units use R-22 Freon. Look on the model and serial tag toIt will usually show how much refrigerant it holds also. A special license is required to handle and purchase refrigerant The fins on my coils are all smashed The fins can be straighten using a fin comb. not effect the unit operation, major fin damage will. Didn't Find Your Answer Here? Or If You Prefer  The Service Dept. All of the information is provided FREE OF CHARGE. No liability is assumed by American A/C & Appliance, any of it's employees, or it's provider for the accuracy of the contents or damages caused by the use of these procedures. electrical supplies, bulbs, fluorescent, general electric, whirlpool, amana, maytag, frigidaire, appliances, tools, test equipment, kenmore, Magic Chef, Admiral, Kitchen Aide,

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