Specifications

27
© 2012 Emerson Climate Technologies, Inc.
Printed in the U.S.A.
AE8-1368 R2
Note: Welded Contactor looks for the presence of motor
voltage after the command to “open” the contactor has been
sent. The E2 will re-load the contactor to prevent single-
phase damage to the motor.
Three scenarios can generate symptoms of a welded
contactor: 1) A welded or sticking contactor, 2) A welded or
sticking pilot relay or 3) A welded or sticking relay switch on-
board the control module.
The following procedure may be followed to help diagnose
the problem
Throw the compressor
motor breaker to shut
down the compressor
Clear the welded
contactor alarm in the
E2
Measure voltage at the
contactor or pilot relay
coil (whichever is driven
by the output from the
ISD compressor)
Is voltage
present?
Failed ISD control
module relay.
Replace control
module
Does relay or
contactor remain
stuck?
Intermittent weld of
contactor, pilot relay or
control module relay.
Replace component that
appears damaged or
continue to monitor closely
Yes
No
No
Replace the contactor
or relay that has failed
Yes
Note: An open high or low pressure
switch will interrupt the welded
contactor protection feature by opening
the contactor circuit
6.7
Forced Run
Welded Contactor Warning
Is the
compressor in
the “forced run”
condition?
Yes
Are there intermittent alarms
for Welded Contactor, and ‘No
Comms to Sensor Module”
warnings?
Graph the voltage
vs demand to
verify this
diagnosis
Verify communication
connectors are solidly
engaged. If
connections are good,
replace the sensor
module.
No
Yes
Diagnose for
intermittent
contactor weld
No