Application Engineering |
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9.Use care when handling the replacement valve – don’t drop the valve or impact the solenoid stem. If the valve is dropped or damaged, discard it and obtain a new valve for replacement.
10.Lightly oil the gaskets with refrigeration oil and hand tighten the new modulation valve into the valve receptacle on the compressor.
11.Using a 7/8” deep well socket and a torque wrench, torque the modulation valve to 230
12.Check for leaks using nitrogen with a properly sized regulating and relief valve.
13.Install the solenoid coil and torque the retaining screw to 25
14.Install the terminal box cover, evacuate the compressor/system, and put the system back into operation.
NOTICE
The above procedures for changing the modulation valve are comprehensive. Depending on the equipment being serviced, additional steps may be required. Refer to OEM instructions for more information.
Copeland Scroll Compressor Functional Check
A functional compressor test with the suction service valve closed to check how low the compressor will pull suction pressure is not a good indication of how well a compressor is performing. Such a test may damage a scroll compressor. The following diagnostic procedure should be used to evaluate whether a Copeland Scroll compressor is working properly.
1.Proper voltage to the unit should be verified.
2.The normal checks of motor winding continuity and short to ground should be made to determine if the inherent overload motor protector has opened or if an internal motor short or ground fault has developed. If the protector has opened, the compressor must be allowed to cool sufficiently to allow it to reset.
3.Proper indoor and outdoor blower/fan operation should be verified.
4.Remove power from the unloader solenoid to load the compressor 100% . With service gauges connected to suction and discharge pressure fittings, turn on the compressor. If suction pressure falls below normal levels, the system is either low on charge or there is a flow blockage in the system.
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5.If suction pressure does not drop and discharge pressure does not rise to normal levels, reverse any two of the compressor power leads (this procedure is for
The solenoid coil should only be energized when it is installed on the solenoid valve. Energizing the coil when it is not installed on the valve will result in a failed coil.
Note: It is also possible that the unloader valve is not closed. With the compressor off, cycle power to the unloader solenoid and listen for clicking. If no sound is heard the valve is very likely stuck.
6.To test if the compressor is pumping properly, the compressor current draw must be compared to published compressor performance curves using the operating pressures and voltage of the system. If the measured average current deviates more than ±15% from published values, a faulty compressor may be indicated. A current imbalance exceeding 15% of the average on the three phases should be investigated further. A more comprehensive
Form No. 6400.
7.Before replacing or returning a compressor: Be certain that the compressor is actually inoperable. As a minimum, recheck a compressor returned from the field in the shop or depot for Hipot, winding resistance, and ability to start before returning. More than
They were misdiagnosed in the field as being inoperable. Replacing working compressors unnecessarily costs everyone.