How To Check Compressor Windings

If the windings test OK, but it still won’t run, then I connect a test cord and try to run it manually. You value your time and money, and so do we. split-phase hermetic motor windings and terminals Split-phase motors used in hermetic refrigeration and air-conditioning applications are designed to start under load. CORRECTION: 1. Abrwholesalers. Single phase compressor start windings are not designed to carry high continuous current like the run winding. For a BLDC motor apply the ac voltage to one pair of the three wires. Check Inverter Refrigerator Compressor: If we working anywhere of inverter Refrigerator Or inverter AC and we want check his Compressor that his Compressor is OK or not, So we should have a PCB kit Because if we turn ON this compressor Direct 220V Volt then this compressor will burned. Starting components have failed 1. Start Capacitors for HVAC Compressors - That large amount of amperage on the compressor windings continuously can slowly degrade the life of the compressor. Reflected voltage waveforms are a function of the switching time and the length of the cable to the motor from the control. Note that, peak horsepower is the maximum output of the compressor motor, given that the motor has an engagement with start winding. Air conditioning troubleshooting when the air conditioning condenser won't run. (4) If continuity exists at any terminal, the compressor is bad and must be replaced. Only the run winding is burned in a single phase motor. s voltage. The voltage should be within 10% of the rating on the compressor tag. In case the compressor fails this way, there are very few repair options you can consider. An A/C compressor clutch coil is a simple device made of fine windings of wire wrapped into a coil. Ohm's law tells you that you can calculate the current through a motor winding if you know the voltage and the resistance of the wire. But if old comp. What happens with the compressor motors is moisture gets in the system and the oil becomes acidic and etches the varnish off the motor windings and when. According to standard IEEE 43: IR test minimum value of the electric motor is a 1 Mega Ohm ( 1 MΩ ). Basic motor testing with multimeters and ammeters July 1, 2015 By David Herres 10 Comments When an electric motor fails to start, runs intermittently, runs hot, or continually trips its overcurrent device, there my be a variety of causes. ALWAYS have an expert check the motor windings to determine whether the single phasing occurred in the input circuit or in the motor windings. Call service l. Start Capacitors for HVAC Compressors - That large amount of amperage on the compressor windings continuously can slowly degrade the life of the compressor. Three electrical windings on the outer part of the motor enable the central rotor to turn, otherwise they would simply vibrate moving backwards and forwards as the current alters direction. Unfortunately all 5 HP compressor motors are not equal in actual power either, to judge the true horsepower the easiest way is to look at the amperage of the motor. restricted feeder tube. VOM to start with or an meger (if we have reason to believe there's an insolation break down occurring). Single-phase motors are found in a long and diverse list of devices like washing machines, mechanical clocks and generators. One of these cords can be handy for test-running other equipment, too. The repair must be done in an open space or with extractor fans to remove the water vapors. If the compressor checks ok and you want to install a replacement start relay. A defective fan will also affect the compressor load and may cause motor protector cut outs or blown gaskets. Refer to the chille r's line wiring diagrams for details. Check if the compressor and fan are working. Squirrel cage motors are very sturdy and hardly give trouble. Check the instruments is under specialized range. The A/C compressor is the heart of the system, and without a good compressor, the unit will not function. You may want to inspect the windings of the motor, to make sure that they are not burnt or a darkened and if you can smell any burnt insulation. or switch of the supply which is connected to the fridge. Check the appearance of motor. What in heck is a start capacitor?. How To Wind Automatic Watch Correctly. Three wires come in from the left of the box. desired to pick up even greater efficiency gains for the total system. The run capacitor does little to help the compressor on startup. The rotor is mounted on a roller bearing at the end with the rectifier. 4 ohm, common to start is usually much higher example 4. 3) REMOVE ALL WIRES FROM THE COMPRESSOR THAT ARE CONNECTED TO THE TERMINALS THAT ARE TO BE TESTED. When the motor is first started, the initial low air flow from the compressor is vented through the unloader valve. Basically the motor is set up with two windings, and to run 220 they connect in series, and to run 112 they connect in parallel. Pull the end bell off the compressor and look at the rotor and stator. An AC compressor contains a motor with start and run windings. Starting capacitor and/or start relay. "Most compressor problems are electrically related," Lattuca said. If a broken start relay is the culprit, replace it so the compressor can have the necessary voltage to operate. Armature Test #1. An A/C compressor clutch coil is a simple device made of fine windings of wire wrapped into a coil. Could that be an issue. When you need to run anything from a framing nailer to a sand blaster, the right air compressor can handle the job with power to spare. (3) Correct compressor overloading. Black) out of the device?. Additionally, students will learn to operate a compressor as well as how to perform an electrical check. Once you have tested a few 3-phase motors, the process will come easily. How to Troubleshoot Fridge Compressors Check the Compressor Windings for an Open Winding. How to Check the Winding Resistance on a 230/460 Volt, 3 phase, 60 Hz, 9 lead motor , Universal Zebra: Testing ECM Motor Winding Sections , Single Phase Induction Motor, How it works ? , How to check the windings of a refrigeration compressor , 12V DC Motor Rewind. That winding won't stand continuous operation, so it's taken out of circuit by a centrifugal switch when the motor reaches a certain speed. How to Size a Run Capacitor for a Compressor? I've been a tech for years, and i always wanted to know is there a formula to make sure that the compressor i'm working on has the right size capacitor? Most compressors don't list cap sizes on the compressor. Featuring a large 42 X 50mm cushion shaped case with contoured rounded angles and thick down turned lugs. Choose the Right Air Compressor By Matt Weber. Hi guys, just to give an update. Check ohms on each pin to the shell. Check the clutch magnetic valve. Check for continuity from the motor leads to the case. Compressor discharge pressure high. Best Airbrush Compressor. When you have open windings always check from terminal to ground with the wires off if you get a reading compressor is bad. For tools like framing nailers , we would recommend you to stick to 5HP-10HP compressors, provided that they come with the essential CFM and PSIG requirement. the compressor may have a brake in the coil winding. Measured Value S to R should be = C to S + C to R. The compressor is engaged by the compressor clutch, made up of a powerful electromagnet and a drive plate. The conductors that carry current are stationary. Compressor: Shut down unit disconnect power, & check resistance of compressor windings at contactor T1-T2, T2-T3. Re: How to Test a compressor Although it's not focused specifically on compressors Megger just put out an article on insulation tester safety that might be useful. When you're removing the compressor leads (wires) from the plug to check resistance through the compressor windings, the pressure of the Freon can launch the plugs with as much as 20,000 pounds of force. There should be no continuity except for the green ground lead. If there is current flow through the RUN winding, but none through the Start winding, either the motor start winding is open or there is a problem with the starting circuit or wiring or connections. A defective fan will also affect the compressor load and may cause motor protector cut outs or blown gaskets. SINGLE PHASE COMPRESSORS (RESIDENTIAL) The resistance of the start winding is approximately 2 ohms to 4 ohms on a 1 ½ ton to 3 ½ ton compressor. RUN WINDING BURN:. Follow recognized safety procedures and practices. Newsletter Back issues. Line voltage is switched to the compressor and fan motor from the board. 5bar the compressor changes over to Idling mode for 20 minutes. I am Using it for foam washing. COMPRESSOR DIAGNOSTIC FLOW CHART From Main Chart Not Running Page Check compressor shell temperature Temp: _____ Shell hot? Yes Overload protector may have tripped. If your vehicle has been running roughly or losing power, there may be a lack of pressure in one or more cylinders. air compressor experts righty went to use the compressor today and it keeps blowing fuses, the motor fired up then blew fue in plug. and it all points to the compressor. Check the power light and emergency button. Find the panel on the side of the compressor; it's held by one or two screws. The light could be staying on in the compartment. 0 WEEKLY MAINTENANCE 1) Check the compressor oil level. When the protector cuts out and the compressor is warm, it can take up to 1 hour before the protector cuts in the compressor again. Having understood the various causes for overheating of AC compressor, it is high time to seek solutions. Two types of shorts can occur in a compressor motor, Check the Thermostatic Control. Only the start winding is burned in a single phase motor due to excessive current flowing through the start winding. We specialize in industrial water coolers, commercial water coolers and much more. NOTE: Hermetic Motor Readings less than 30 megohms may indicate moisture in the system or refrigerant in the motor/compressor. Check Compressor Mounting — Loosen compres-sor mounting bolts and remove shipping blocks from under compressor. Compressor runs but will not load A screw compressor can run loaded (‘pumping air’) or unloaded (‘idle’). AC Motor Winding Resistance Test Check the motor winding resistance or ohms reading with a multimeter. You should be reading a few ohms between each winding depending on what kind of compressor you are talking about. Contact Traulsen Technical. 22) When found everything in order put the compressor air discharge net to supply compressed air for plant utilities. We have a 5 HP 60 gallon single-stage air compressor (Quincy QTS5) that has been overheating lately causing the thermal switch to trip. Why Does My Electric Motor Humm And Not Start? Charles in Pittsburg, Missouri asks: How can I Diagnose an Electric Motor Problem? Common Problems with Electric Motors and Capacitor Start Motors, How to Check an Electric Motor, Diagnostic Checks You Can Make When an Electric Motor Will Not Start. While it would nice for someone to simply tell you what the best air compressor is, the question is actually impossible to answer. Remember that the BLDC motor is usually connected in WYE. There should be no reading at all, from any of the terminals to ground. compressor. grounded will be checked in same way. The ohmmeter will read the resistance of the starting and running windings. Check the resistance of the windings to make sure they are within the manufacturers specs. Since there are three terminals - S, C, R -in a single phase motor, measure winding resistance: C to S, C to R and S to R. Check for the presence of contaminants that affect the results of IR testing. A hermetic compressor unit works as follows; as the compressor builds up pressure, the current increases, causing the windings to get hot, but at the same time, the cooling refrigerant, passes around the heated windings. On a compressor with a crankcase sight glass, flooding can be observed as constant foaming of the oil during run. Does not start, run, hum or anything 5. See Trouble Shooting Thermostat for details and information on how to verify if this is the problem. Next, go to the compressor electrical connection box on the compressor and open the…. You'll hear a distinctive click when the compressor is energized as the drive plate is pulled into place. Good packaging, which will ensure all parts to be delivered safely to customer;. If necessary use the extension block as in Fig. air method in which the compressor is heated an oven while dry air is passed thru the comp­ ressor and over the motor windings. The compressor is an electrical motor connected to a precision pump. The amp draw will be double on 110. Start capacitor seems to be okay. Tips for finding common, start and run on a compressor I'm having trouble finding common, start and run on compressor with my metering device. However, the compressor could still be locked (stuck) internally. Hi guys, I've got a ice cream display which when the compressor turns on it trips the circuit breaker. Someone has cut the refrigerant line to the compressor. When the circuit is turned on, the PTC thermistor has a low resistance, allowing current to pass through the startup winding. Technicians should perform a series of tests on an electric motor during routine preventive maintenance or before replacing it; this includes testing the motor for grounded windings. Piston air compressor vacuum pump units from Grainger feature aluminum cylinders and heads and thermally protected shaded-pole motors with high torque start windings. Thus the readings will be. The overload protector is accessed from the lower rear of the refrigerator. Then check to see if they are grounded. The system begins to cool and the technician leaves the job. Display will show 01-ON or 02-OFF. Measured Value S to R should be = C to S + C to R. In the applications mentioned above, efficiency is not an important performance consideration, but high efficiency is desired in a compressor. Compressor runs for a few seconds and then trips the breaker. digit 10 compressor motor protection code type protection phase description 1 capacitor run - capacitor start 1 induction run - capacitor start 3 six lead part winding or across the line except 575 volt compressor motor type 3 misc. The compressor clutch coil is a common failure item. It's not the easiest task for a do-it-yourselfer to complete, but with a little focus and determination, it can be done. Unfortunately all 5 HP compressor motors are not equal in actual power either, to judge the true horsepower the easiest way is to look at the amperage of the motor. Check for grounded windings by reading from each terminal to a good ground on the cabinet. Using a Megohmmeter complete the same steps as “checking a short to ground”. Second, insulation-resistance-testing results should be checked to ensure they have not been affected by the presence of contaminants. Correct faulty connections: 3. Correction of the problems found, followed by a detailed start-up and check will eliminate future repeat failures. If your compressor trips on over temperature, it could be any of the following: Ambient temperature too high or not enough ventilation. How To Test or Check Air Conditioner Compressor Motor Windings. If voltage is present, go to step 3. Check Warranty Status. Next, check for short-circuit between phases. CORRECTION: 1. Check ohms on each winding. Single-phase motors are found in a long and diverse list of devices like washing machines, mechanical clocks and generators. When you need to run anything from a framing nailer to a sand blaster, the right air compressor can handle the job with power to spare. This cools the motor windings. Long story short, a failed compressor may be a reason for system replacement. Air conditioner or heat pump compressor burn-out diagnosis & repair: This air conditioning repair article discusses the how to diagnose and replace a burned out air conditioner compressor, including evaluation of air conditioner compressor noises, hard starting, lost cooling capacity, and detection of a burned out compressor or A/C compressors at or near end of their life. A lot of folks are interested in this page about I turn a Husky compressor on and nothing happens!While a linked page on this site about Husky air compressors offers visitors a broad range of info about this brand, this page is about this one specific issue with Husky compressors. Check the required specifications for your particular type of compressor clutch in the illustrated section of the A/C parts catalog. * START WINDING BURN The start winding only of a single-phase motor is uniformly overheated or burned. If you find a spot burn at the bottom of the compressor check the clearance between the rotor and stator. Hi guys, just to give an update. How To Test the Compressor Motor. Try to swing manually the rotor shaft check the bearing condition. Since it is a motor, it has windings just like any other motor. A defective control board won’t properly sense when the compressor needs to run, meaning your refrigerator can’t maintain the set temperature. Winding and Ground Check: Over time, the compressor winding insulation can break down due to high temperatures caused by poor power supply quality or excessive operating temperatures. What may be a fantastic unit for light duty use around the house may be completely useless at a construction site. The split phase motor has two windings, a start winding and a run winding. Sep 6, 2019- Air Conditioning Repair - How to ohm a compressor - YouTube. Check for Power. If the windings test OK, but it still won’t run, then I connect a test cord and try to run it manually. So the readings I get are not 'so' off but there are a bit off. Check between the common and the start winding for ohms between 6-8 ohms , not open (o-ohms). The most common failure mode of a 3 phase AC motor is burnt winding or shorted winding leading to the damage of the motor. The conductors that carry current are stationary. com Describes the use of an ohmmeter to check the windings of a single phase air conditioning compressor motor. Often times this is misdiagnosed as a compressor failure. For example, a continuous duty, 40°C rise motor will stabilize its temperature at 40°C above ambient (surrounding) temperature. If there is resistance, the overload is open. Placing the two run windings in series yellow to red to 2 gives 230 from black to 1 and to green. Now, we can identify the problem to either the cable or the motor. ALWAYS have an expert check the motor windings to determine whether the single phasing occurred in the input circuit or in the motor windings. Check that the correct voltage is applied to the motor. Failure to properly ground the frame of the motor can cause serious injury to personnel. Troubleshooting compressor electrical motor failures caused by refrigeration system problems. , plot as sticker and stored it in clamp meter case. Describes the use of an ohmmeter to check the windings of a single phase air conditioning compressor motor. Check airways are fully clear, which may require jet washing, as blocked evaporators will potentially lead to liquid return to the compressor / pack, which in turn, will cause mechanical damage or worst case, a full failure to the compressor. Common to Run for run winding resistance. A single primary winding wrapped around a laminated magnetic core is used as in the auto transformer but instead of being fixed at some predetermined tapping point, the secondary voltage is tapped through a carbon brush. Write down the value from. air method in which the compressor is heated an oven while dry air is passed thru the comp­ ressor and over the motor windings. Insulation resistance testing to check for degradation of motor winding insulation; Check for the presence of contaminants that affect the results of IR testing. "Refrigerator Condenser Fan. To determine which winding is which, a multimeter must be used to measure the resistance of each winding. W hat Customers and Subscribers are saying How-to Articles. Taking the time to learn how to test a refrigerator start relay can help you find any problems, fix them, and ultimately save you the money you'd have to spend on a new one. part winding contactor each contactor for one winding. The compressor motor needs the capacitor to start and as report, they need changing. Does not start, run, hum or anything 5. Community Experts online right now. For example, a continuous duty, 40°C rise motor will stabilize its temperature at 40°C above ambient (surrounding) temperature. Go shopping– it’s not worth fixing. Check the insulation resistance of motor winding using Insulation tester meter on 500 Volt scale. Applications include automotive, hoists, lifts and cranes as it has a high starting torque. Then you use the ohm meter sett on R x 1 scale and check the compressor windings. Next, check for voltage at the compressor. or switch of the supply which is connected to the fridge. Long story short, a failed compressor may be a reason for system replacement. The process of cooling involves utilizing chemicals that are converted from a gas to a liquid and then back to a gas again. How To Detect Aircon Gas Leaking Problem? Aircon gas leaking is a problem that should be dealt with as soon as it occurs. The recommended superheat at the compressor is 20 degrees. Compressor motor has open winding(s) 5. * START WINDING BURN The start winding only of a single-phase motor is uniformly overheated or burned. First, let me say that a short to ground on a compressor is most often not a defect in the manufacture of the compressor, but deficiencies elsewhere in the system. There are a considerable number of electric motors in your home. How to Troubleshoot Fridge Compressors Check the Compressor Windings for an Open Winding. Check all of 3 connection to earthing or compressor body( scratch out the paint from compressor body to get a continuity). A multi-meter is a handy tool for guitar players to have on their work bench. Describes the use of an ohmmeter to check the windings of a single phase air conditioning compressor motor. • Compressor problems can be mechanical or electrical ELECTRICALLY CHECK A SINGLE-PHASE COMPRESSOR • Make certain wires are disconnected from the compressor • Make certain all compressor terminals are clean • Check resistance from windings to ground (ohmmeter or megohmmeter) • Check resistance of the start and run windings. air method in which the compressor is heated an oven while dry air is passed thru the comp­ ressor and over the motor windings. The owner’s manual can tell you whether your vehicle needs regular unleaded or premium gasoline. Check supply power. Air conditioning troubleshooting when the air conditioning condenser won't run. Ask for FREE. If the compressor is a 3phase type it will have 3 equal resistances between c r s. Check compressor windings, start relay and overload protector. First, insulation-resistance testing should be conducted to check for degradation of motor-winding insulation. Buy FIXMAN Italy 2HP Vertical Belt Type Industrial Air Compressor in Valenzuela,Philippines. There are a lot of different kinds of air conditioner compressors. If any of the original posters are still on here, can and will you please re-post a good link. Compressor discharge pressure high. On complete systems submitted to UL, the rated load amp value will be determined by actual system tests. If the compressor windings check good, this is not diagnostically conclusive that the compressor itself is good. If the compressor is running then check the evaporator coils to see if they are frozen over or if there is very little frost pattern. While the method of checking the capacitors is the same, this whole discussion is about run capacitors because it’s about a motor not having the power to keep running under higher loads…. Collect the motor data from motor NAME PLATE. When a compressor has shorted out, the plug can overheat and get soft. Monitor unit, if alarm remains active or is repetitive replace the compressor at the next available opportunity, refer to COMPRESSOR Service Section 6. Any reading on the multi meter’s ohm scale means the motor windings are failing and will need to be replaced. • Tests start and run capacitors and system relays by substitution. These clutches may involve adding or removing shims to properly gap. If there is a fault, it pops out. If amperage exceeds 40% of FLA, check for an. Now, we can identify the problem to either the cable or the motor. • Check for damaged, miswired. You have been signed out due to in-activity the last 120 minutes. air in system. Failure to properly ground the frame of the motor can cause serious injury to personnel. There should be no reading at all, from any of the terminals to ground. You will need an ohm meter to determine the windings. Only the start winding is burned in a single phase motor due to excessive current flowing through the start winding. I am going to replace both of those. Application: - Laboratory and medical. * Most compressor motor windings have a common connection internal to the compressor so windings can't be isolated. The current drawn is about 17. Just what you've been looking for. Check ohms on each winding.  Check electrical power to solenoid valve. low air (evaporator) low refrigerant charge. Single-phase motors are found in a long and diverse list of devices like washing machines, mechanical clocks and generators. These clutches may involve adding or removing shims to properly gap. So, after the compressor has been running for a bit, the load increases as it builds system pressure, the motor is working harder and because of the faulty capacitors the compressor stalls and the input current goes way up, blowing the breaker. The megger will help to detect areas of deteriorating insulation where the windings may soon short. What in heck is a start capacitor?. High temperatures break down the motor winding insulation, which may cause a loss of electrical resistance and result in a short to the ground or even an open winding. Blown Fuses 2. There are a lot of different kinds of air conditioner compressors. You have to disconnect the star junction and megger test between terminals,1&2, terminals, 3&2 andBertween 1&3. But you can (and should!) check the resistances in all three windings to rule out an open winding. control one compressor motor stop/start contactor, one compressor motor transition contactor, one oil heater, three solenoid valves (compressor load, compressor unload, step loader), and up to four fan motor contactors or groups of contactors. I understand that one could power up the motor and check the current being pulled by each phase, if there is a serios unbalance on a single winding, then turn that winding around, BUT I would like clarity on how to sort out the windings start and end before power up. If the fans are running and your compressor won't start or if you hear a clicking sound from the unit, check the overload relay for signs of overheating or arcing. Next, check the windings of the fan motor for an open or a short. and it all points to the compressor. If I can't start it that way, it's most likely a mechanical problem, most often binding bearings, and the 'bottom line's the same: either the compressor or refrigerator will have to be replaced (I'll be discussing test cord. You should have infinite resistance on each pin to the shell of the compressor. POST a QUESTION or READ FAQs about installing a hard-start capacitor to get an air conditioner motor, fan motor, or other electric motor running. M500 OPERATION 1) READ THE M500 INSTRUCTIONS CAREFULLY TO GET A FULL UNDERSTANDING OF THE M500 AND HOW IT OPERATES. The electric motor in your fridge's compressor has two windings in it; a START winding and a RUN winding. Squirrel cage motors are very sturdy and hardly give trouble. It is evident from the phasor diagram that the current through the starter winding Is leads the voltage V by a small angle and the current through the main winding Im lags the applied voltage. If a compressor seizes, it may burn out the electrical motor, causing the electrical windings to short out. Re: How to Test a compressor Although it's not focused specifically on compressors Megger just put out an article on insulation tester safety that might be useful. 25 ohms, the rated resistance value for the run winding is 1. Refer to the chille r's line wiring diagrams for details. For example it should read maybe 3 across one set (by set I mean 2 terminals), then 5 on another and 8 on the other set. If the readings are out of spec, replace the entire compressor clutch. Usually this will ignite the oil causing a burnout. Check the required specifications for your particular type of compressor clutch in the illustrated section of the A/C parts catalog. Then check to see if they are grounded. Power is applied to the compressor motor windings through the overload device, and the relay is used to add the start winding in the circuit until the compressor is at running speed. ELECTRIC MOTORS. You should be reading a few ohms between each winding depending on what kind of compressor you are talking about. Since there are three terminals - S, C, R -in a single phase motor, measure winding resistance: C to S, C to R and S to R. WHY REFRIGERATION SYSTEMS FAIL: If the engineer connects the gauges (usually during a service) and does not purge the air out of the gauge lines this can introduce moisture into the system. To do this, you’ll have to measure the ohms. Defrost and reset temperature i. The PTC relay starts the compressor inside the fridge to make cold air so your food stays cool. I know the resistance readings should be closer together. While it would nice for someone to simply tell you what the best air compressor is, the question is actually impossible to answer. Set your voltmeter to measure ohms, and place a probe on each large terminal (see image below). I show how to ohm compressor windings with a megohmmeter. (Winding temperature 20 , 68°F) Measure the resistance between the terminals with a tester. In the refrigerator compressor we have three terminals but it is very hard to identify compressor terminals or find out that which one is start, run and common. You sprang a freon leak or you got an iceplug in the cap tube. As in case of split AC both these items are fixed outside the house. I understand that one could power up the motor and check the current being pulled by each phase, if there is a serios unbalance on a single winding, then turn that winding around, BUT I would like clarity on how to sort out the windings start and end before power up. 1) winding to winding short. Checking the Compressor Windings. Is the brown wire from EasyStart connected to the compressor R winding only? On the top of the compressor there is a cover held by a single hex nut that looks similar to the one pictured below: Some caps have the windings marked on the top as shown while others have markings inside the cap. Often it is required to test the winding of the 3 phase windings with the aid of a multimeter or ohmmeter to determine whether the motor is still good or burnt or shorted. You can then control the solenoid valve by whatever means pleases you to allow the compressor to come up to speed without load. power to contactor. air compressor experts righty went to use the compressor today and it keeps blowing fuses, the motor fired up then blew fue in plug. Where the stator is an electromagnet, the coil which energizes it is known as the field coil or field winding. A compressor group may include special characters * or ^, compressor with this designation may be used as substitutes within the group as noted. Check that the windings are not open or blown. 1 of three could open when hot. The process. If there is a continuity, check the contuity of terminals 1 and 3, assuming the motor is wye connected. A main concern is the amperage requirements of the compressor. Starter windings on larger motors.