Emerson AE4-1287 R7 User Manual

17
© 2012 Emerson Climate Technologies, Inc.
Printed in the U.S.A.
AE4-1287 R7
Application Engineering
BULLETIN
is closed. If correct control voltage is not present,
replace the module.
3. If correct control voltage is present, make sure there
is a full sight glass of liquid from the receiver at the
injection valve. If there is not a full sight glass of
liquid, the piping from the receiver should be checked
before proceeding.
Piping connections and sizes must be chosen to
assure a full sight glass of liquid for the injection
valve during any phase of the refrigeration system
operation. Piping that is too small, or connections
taken from the tops of manifolds rather from the
bottom may result in a lack of refrigerant available
for the injection valve just when it needs it most,
such as after a defrost.
If a full sight glass is present and frost still does not
form, replace the injection valve.
4. With the module sensor connector shorted or
open and the module and compressor running,
the module should trip in one minute and stop the
compressor.
If the compressor does not stop, check the control
circuit wiring to be sure the module is wired to stop
the compressor when the module trips. If the wiring
is correct, replace the module.
5. Check the discharge temperature by performing
Steps 1-6 of the Injection Valve is Cycling On and
Off test.
If the discharge temperature is higher than the
allowable Table 2 selection, remove the sensor
from the compressor and use the Bench Check of
the Sensor Test to check the probe. Replace the
sensor if necessary.
End of Test
If the Injection Valve is Continually Injecting
1. Make sure there is a full sight glass of liquid from
the receiver. If there is not a full sight glass of liquid,
there may not be enough liquid to allow Demand
Cooling to cycle because it uses all available
liquid to keep the discharge temperature below
a dangerous level. The piping from the receiver
to the injection valve should be checked before
proceeding.
Piping connections and sizes must be chosen to
assure a full sight glass of liquid for the injection
valve during any phase of the refrigeration system
operation. If the suction pressure rises then go to
Step 6.
2. Deenergize the system and disconnect the sensor
from the module. Energize the system so the
compressor is running. The frosting should stop.
If Step 2 is successful, go to Step 4 otherwise
continue to Step 3.
3. If frosting does not stop, with the sensor
disconnected, deenergize the system. Disconnect
the voltage supply to the injection valve and restart
the compressor. If frosting does not stop, replace
the injection valve. If frosting stops, replace the
module.
4. If frosting stops when the sensor is disconnected,
check the system for high suction and/or condensing
temperatures before proceeding. As suction and/or
discharge temperatures rise toward the Demand
Cooling limits (40° F evaporator temperature, 130°F
condensing temperature), Demand Cooling will call
for injection for longer periods of time and may
appear to be continuously injecting. Use Figure 1
to check Demand Cooling operating areas. Figure
1 shows where injection begins for two return gas
temperatures (65°F and 20°F) for R-22. The arrows
marked (A) and (B) on the graph show the lowest
allowable evaporating temperatures using a given
condensing temperature.
Point (A) shows that with 65°F return gas and 110°
F condensing temperature, the lowest evaporating
temperature without Demand Cooling injection
is -5°F. Point (B) shows that if the return gas
temperature can be lowered to -20°F, while still at a
condensing temperature of 110°F, the evaporating
temperature may be lowered to -20°F without
Demand Cooling operation.
Your injection point can be approximated by
drawing a line representing your return gas
temperature in between and parallel to the two
return gas temperatures on the Figure 1 (Area
2). The higher your return gas temperature is,
the closer it will be to the “65°F line”. The lower it
is, the closer it will be to the “20°F line”. You can
then draw your own dotted lines representing your
condensing and evaporating temperatures to see if
you are in the in a Demand Cooling injection zone.
The higher your condensing temperatures are for a
given evaporating temperature, the more injection
is required until fi nally Demand Cooling may be
energized constantly.
If the suction and condensing temperatures are
lower than, or borderline to the injection areas of
Figure 1 then go to Step 5.
If they are much higher the system should be
corrected to lower the temperatures or there may

Emerson AE4-1287 R7 Specifications

General

Brand	Emerson
Model	AE4-1287 R7
Category	Refrigerator
Language	English