Emerson AE4-1395 Manuel D’Utilisation

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© 2012 Emerson Climate Technologies, Inc.

Printed in the U.S.A.

Application Engineering

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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. 

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 

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 

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 in-lbs.

12.  Evacuate the compressor/system and put the 

system back into operation.

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.

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 o-ring and white Teflon gasket are removed

with the valve and do not remain on the valve 

receptacle.

8.  The replacement valve should have a new, 

black  o-ring  and  white, Teflon  gasket  as  shown: