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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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 in-lbs.

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 in-lbs.

14. Install the terminal box cover, evacuate the 

compressor/system, and put the system back into 

operation.

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. 

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.

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 3-phase compressors only) and 

reapply power to make sure compressor was not 

wired to run in reverse direction. If pressures still 

do not move to normal values, either the reversing 

valve (if so equipped) or the compressor is faulty. 

Reconnect the compressor leads as originally 

configured and use normal diagnostic procedures

to check operation of the reversing valve.
The solenoid coil should only be energized 

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 trouble-shooting sequence 

for compressors and systems can be found in 

Section H of the 

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 one-third of compressors 

returned to Emerson for warranty analysis 

are determined to have nothing found wrong. 

They  were  misdiagnosed  in  the  field  as  being

inoperable. Replacing working compressors 

unnecessarily costs everyone.