compressor oil and refrigerant. This power interruption thus stops the compressor motor • Module provides protection against: • Abnormal locked rotor conditions • Loss of refrigerant • Repeat steps 1-11. Verify that the refrigerant levels are correct. When a motor experiences damage or malfunction, frequently the motor’s electrical resistance will deviate from what it’s normal value is. Manually rotate the direct-drive clutch and feel for a slight resistance or drag. On your unit (if I interpret the readings correctly) has winding resistances of 17.9 and 1.1 ohms with a series resistance of 18.8 This would be 20.9 ohms for the in series measurement. Remove shunt across compressor terminals and restore to proper electrical connections. In that case, insulation resistance of t he compressor will fall. Sensor resistance values change with temperature variations • Module will interrupt power to the contactor coil when resistance values of sensors exceed the specified range. So the readings I get are not … The resistance values can be found in the service manual for the corresponding unit. Place compressor in operation for 5 or 10 minutes. If the megger reads a resistance under 1 (1,000 ohms) on your meter after the initial 60-second interval, the cable has failed and the cable should be removed. What resistance value would tell you that a compressor is burnt? Record resistance value and terminal temperature. Contractor's Assistant: I'll do all I can to help. Therefore, please design the refrigerant pipeline so that liquid height of residual compressor oil and refrigerant maintained in the compressor above external bottom lower than 277mm. However, each make, model and size compressor will yield somewhat different values. I put it in, leak checked, pulled vacuum, dropped in factory charge (starting point for my charge,) now compressor wont start. “Ohming out a motor” is the process of measuring the electrical resistance of the motor windings and comparing that resistance to normal values. Single phase, 208/230 volt w/ danfoss scroll. This method is good for detecting grounded or open windings and windings that are suspect (resistance too high). Hi guys, just to give an update. If the compressor suffers a catastrophic internal failure, the shear pin or clutch plate breaks, separating the seized compressor from any other driven components. If the megger reads a resistance between 1-1.25 on your meter, then the cable passes. This is where confusion often sets in. Tell me a bit more about what's going on so we can help you best. * Most compressor motor windings have a common connection internal to the compressor, so windings can't be isolated. The breaker trips when the compressor starts. I did find a tech sheet for a FR8.5G compressor, it gives the winding resistances as 8.9 and 12 ohms. Real quick history on the unit, two weeks ago construction supervisor noticed leak in condensing coil, ordered part and sent me to install. I had a look at the data sheet of the compressor (NJ2212GK) and the resistance rating for the start winding is 7.25 ohms, the rated resistance value for the run winding is 1.95 ohms. If the system is overcharged, the pressure in the system will naturally be higher than what it is supposed to be causing the discharge temperature to be higher. Use the higher resistance range on your meter to detect grounded windings. Any reading above 1.25 is considered excellent. 2 Fluke Corporation Insulation resistance and electrical testing for HVAC compressor motors What to look for There’s no hard and fast pass/fail rule for how to interpret insulation resistance values, but manu-facturers and agencies seem to agree that IRT trending can be a … As richappy said it sounds like your compressor is toast. The resistance readings between the 3 pins are 1.1 Ohms (between the compressor pins that are ultimately connected to the line voltage), 18.8 Ohms, and 17.9 Ohms. Resistance between C and S is about 2.3 Ohms. Hey guys, working on a 5 ton York split system straight cool at a fire station. To check the clutch, remove the drive belt tension. He compressor will yield somewhat different values the clutch, remove the drive belt.... Values can be found in the service manual for the corresponding unit to detect grounded windings electrical connections compressor and! 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