Step 5 - Check Operation Of The Exv; Alarms And Alerts - Carrier Air Conditioner Operation And Service Manual

2. Make sure that thermistor leads are connected to the
proper pin terminals at the J5 connector on EXV board
and that thermistor probes are located in proper position
in the refrigerant circuit.
When these checks have been completed, the actual opera-
tion of the EXV can be checked by using the procedures out-
lined in Step 5 — Check Operation of the EXV section below.
STEP 5 — CHECK OPERATION OF THE EXV — Use
the following procedure to check the actual operation of the
EXVs. The ENABLE/OFF/REMOTE contact switch must be
in the OFF position.
1. Close the liquid line service valve for the circuit to be
checked and run through the appropriate service test to
pump down the low side of the system. Run lead com-
pressor for at least 30 seconds to ensure all refrigerant
has been pumped from the low side and that the EXV
has been driven fully open (1500 steps).
NOTE: Do not use the Emergency ON-OFF switch to
recycle the control during this step.
2. Turn off the compressor circuit breaker(s) and the control
circuit power and then turn the Emergency ON/OFF
switch to the OFF position. Close compressor service
valves and remove any remaining refrigerant from the
low side of the system.
1
3. Carefully loosen the 2-
Remove the motor canister from the valve body using
caution to avoid damage to the o-ring seal. If the EXV
plug was disconnected during this process reconnect it
after the motor canister is removed.
4. Note position of lead screw (see Fig. 15). If valve has re-
sponded properly to processor signals in Step 5.1 above,
the lead screw should be fully retracted.
5. Recycle the control by turning the Emergency ON-OFF
switch to the ON position. This puts the control in initial-
ization mode. During the first 60 seconds of the initializa-
tion mode, each valve is driven to the fully closed posi-
tion (1500 steps) by the processor. Observe the move-
ment of the lead screw. It should be smooth and uniform
from the fully retracted (open) to the fully extended
(closed) position.
6. When the test has been completed, carefully reassemble
expansion valve. Apply a small amount of O-ring grease
to the housing seal O-ring before installing the motor can-
ister. Be careful not to damage the O-ring. Tighten the
motor nut to 15 to 25 lb-ft (20 to 34 N-m). Evacuate the
low side of the open refrigerant circuit. Open compressor
service valves and close compressor circuit breakers.
/ in. nut. Do not twist the valve.
8
Open liquid line service valve. Check for any refrigerant
leaks. Turn the ENABLE/OFF/REMOTE switch back to
ENABLE or REMOTE and allow the unit to operate.
Verify proper unit operation.
NOTE: The EXV orifice is a screw-in type and may be
removed for inspection and cleaning. Once the motor canister
is removed the orifice can be removed by using the orifice
removal tool (part no. TS429). A slot has been cut in the top of
the orifice to facilitate removal. Turn orifice counterclockwise
to remove. A large screwdriver may also be used.
When cleaning or reinstalling orifice assembly be careful
not to damage orifice assembly seals. The bottom seal acts as a
liquid shut-off, replacing a liquid line solenoid valve. If the bot-
tom seal should become damaged it can be replaced. Remove
the orifice. Remove the old seal. Using the orifice as a guide,
add a small amount of O-ring grease, to the underside of the or-
ifice. Be careful not to plug the vent holes. Carefully set the
seal with the O-ring into the orifice. The O-ring grease will
hold the seal in place. If the O-ring grease is not used, the seal
O-ring will twist and bind when the orifice is screwed into the
EXV base. Install the orifice and seal assembly. Remove the
orifice to verify that the seal is properly positioned. Clean any
O-ring grease from the bottom of the orifice. Reinstall the ori-
fice and tighten to 100 in.-lb (11 N-m). Apply a small amount
of O-ring grease to the housing seal O-ring before installing the
motor canister. Reinstall the motor canister assembly. Tighten
the motor nut to 15 to 25 ft-lb (20 to 34 N-m).
Alarms and Alerts —
or fault conditions, and may cause either one circuit or the
whole unit to shut down. They are assigned code numbers as
described in Table 29.
Automatic alarms will reset without operator intervention if
the condition corrects itself. The following method must be
used to reset manual alarms:
Before resetting any alarm, first determine the cause of the
alarm and correct it. Enter the Alarms mode indicated by the
LED on the side of the Scrolling Marquee Display. Press
and until the sub-menu item RCRN "RESET
ENTER
ALL CURRENT ALARMS" is displayed. Press
The control will prompt the user for a password, by displaying
PASS and WORD. Press
word, 1111. Press
ENTER
has been changed, use the arrow keys to change each individu-
al character. Toggle the display to "YES" and press
The alarms will be reset.
48
These are warnings of abnormal
ENTER
to display the default pass-
ENTER
for each character. If the password
ENTER
.
.