Application Engineering |
|
|
|
|
B U L L E | T | I | N |
|
SERVICE PROCEDURES
Modulation Troubleshooting
The modulation valve and solenoid coil are engineered for specific use with the digital scroll. Don’t attempt to substitute replacement solenoid coils that are not of the correct part number. The 3 to 7.5 ton modulation valves must be installed in the correct orientation and with the arrow on the valve pointing to suction. Installing a modulation valve in a horizontal position, or with the suction and discharge connections reversed, can result in sporadic operation of the modulation valve. See Figure 8 for an illustration of the correct valve location and orientation.
Figure 10 is a troubleshooting flow chart to help with simple modulation problems. For more information on troubleshooting the Copeland™ Digital Compressor Controller please refer to AE8-1328. For more information on troubleshooting the Emerson Commercial Comfort Controller please refer to AE8-1393.
3 to 7.5 Ton Modulation Valve Replacement Procedure
The 3 through 7.5 ton digital scroll compressors employ a modulation valve that is mounted external to the compressor in the modulation tubing. To replace the modulation valve, follow these recommended steps:
1.Disconnect and lockout the power to the unit.
2.Recover the refrigerant charge from the compressor/ system.
3.Remove the screw holding the coil to the valve using a Phillips screwdriver or appropriate size nut driver.
4.Remove the coil from the valve.
5.Using manifold gauges, double check to make sure the refrigerant charge is completely recovered from the compressor before proceeding.
6.Using tubing cutters, cut the modulation tubing close to the valve body leaving the valve tubing stubs in the suction “T” connection and the swaged tubing from the compressor top cap.
7.Carefully unbraze and remove the tubing stubs from the suction “T” and top cap tubing swage. Carefully unbrazing and removing these stubs will allow the tubing/suction “T” fitting to be reused.
8.After these fittings have cooled, clean the fittings and prepare to braze the new valve in place. Wrap a wet rag around the valve body to keep from overheating the valve.
9.Using standard brazing practices for refrigeration
© 2012 Emerson Climate Technologies, Inc. | 10 |
Printed in the U.S.A. |
|
systems, carefully braze the new valve into the system, directing the torch flame away from the valve body.
10.Check for leaks using nitrogen with a properly sized regulating and relief valve.
11.Install the solenoid coil and torque the retaining screw to 25
12.Evacuate the compressor/system and put the system back into operation.
8 To 15 Ton Modulation Valve Replacement Procedure
The 8 through 15 ton digital scroll compressors have a modulation valve that is replaceable in the event the valve stops functioning. The modulation valve threads into a receptacle that is inside the small terminal box on the compressor. To replace the modulation valve, follow these recommended steps:
1.Disconnect and lockout the power to the unit.
2.Recover the refrigerant charge from the compressor/ system.
3.Remove the cover from the small terminal box and remove the screw holding the coil to the valve using a Phillips screwdriver or appropriate size nut driver.
4.Remove the coil from the valve and clean the area around the valve body to prevent debris and dirt from entering the system when changing the valve.
5.Using manifold gauges, double check to make sure the refrigerant charge is completely recovered from the compressor before proceeding.
6.Using a 7/8” deep well socket and ratchet, turn the valve counterclockwise to remove the valve.
7.Visually inspect the valve receptacle on the compressor for damage or debris. Ensure that the black
8.The replacement valve should have a new, black
