|
1.
Pressure transducer alarm (SP, PRSR) |
|
Cause |
Solution |
Bad
transducer
|
Replace the pressure transducer
|
Out
of range
|
Turn off power for a few seconds, turn back on
|
Loose wire
|
Wire correctly |
|
Wrong hook-up |
Wire correctly |
|
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2.
Outlet sensor TS2 fails (So, SCSR) |
|
Cause |
Solution |
|
Mechanical damage |
Replace sensor |
|
Connection wire loose |
Tighten the connection
wires on the controller terminal |
|
Overheated |
Allow sensor time to
cool down and check again. If no response, replace
sensor. |
|
Out of range |
Turn off power for a few seconds then turn back on |
|
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3.
Room sensor TS3
fails (SA, RMSR) |
|
Cause |
Solution |
|
Mechanical damage |
Replace sensor |
|
Connection wire loose |
Tighten the connection
wires on the controller terminal |
|
Overheated |
Allow sensor time to
cool down and check again. If no response, replace
sensor. |
|
Out of range |
Turn off power for a few seconds then turn back on |
|
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4. Low superheat |
|
Cause |
Solution |
|
Superheat setting too low |
Change to correct
setpoint (see
manual) |
|
Wrong location of TS2 |
Re-locate the outlet
temperature sensor to the proper location (see
manual) |
|
Sensors loose |
Make sure the outlet
sensor is properly insulated |
|
Uneven feeding of coil
circuits |
Make sure the
distributor is feeding each circuit evenly |
|
Refrigerant overcharge |
Use correct refrigerant
charge |
|
Defective electric
expansion valve (EEV) |
Replace valve |
|
Compressor stopped |
Check compressor |
|
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| |
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5.
High room
temperature (rH, HIRM) |
|
Cause |
Solution |
|
Insufficient refrigeration |
Check system design to
select a sufficient system |
|
Heat
load too large |
Call factory at
800-684-8988 for sizing recommendations |
|
Compressor failed or
high pressure has cut out |
Re-set pressure
control, clean condenser coil or replace failed
compressor |
|
Evaporator fans not running |
Make sure fan relay
on control board is closing |
|
Walk-in door open
too long |
Make sure door is
closed |
|
Coil iced up |
Check for possible
air leak through walk-in walls |
|
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6. Low room
temperature (rL, LORM) |
|
Cause |
Solution |
|
Improper low temp setpoint |
Change setpoint |
|
Over-designed system |
Call factory at
800-684-8988 for sizing recommendations |
|
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| |
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7.
Defrost termination
sensor TS1 fails (Sd, INSR) |
|
Cause |
Solution |
|
Mechanical damage |
Replace sensor |
|
Loose connection wire |
Tighten the connection
wires on the controller terminal |
|
Overheated |
Allow sensor time to
cool down and check again. If no response, replace
sensor. |
|
Out of range |
Turn off power for a few seconds then turn back on |
|
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| |
|
8.
Low pressure
alarm (LP, PAL) |
|
Cause |
Solution |
|
Refrigerant leak |
Fix
leak |
|
Bad
pressure transducer |
Replace transducer |
|
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9.
Communication
alarm (CA, CMAL) |
|
Cause |
Solution |
|
Loose RS-485 connection |
Tighten terminals |
|
Failed communications port
Improper setpoint in the Cn parameter |
Replace controller board
Verify setpoints are correct for application
(see
manual) |
|
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10.
Electronic
expansion valve troubleshooting |
|
If
the valve stops moving, depending upon how far open
it is, one or more alarms may be displayed. These
alarms include a low superheat alarm, a low
temperature alarm and/or a high temperature alarm.
Use the following steps to
troubleshoot the valve:
-
Disconnect the valve from the
controller
-
The resistance between the
black and white leads should be 90 ohms. The
resistance between the black and red leads
should be an open.
-
The resistance between the
red and green leads should be 90 ohms. The
resistance between the white and green leads
should be an open.
-
The resistance between each
lead and the brass housing of the valve
should be an open.
-
Read the AC, not DC, voltage
across the black and white leads while the
valve is moving. The AC voltage should be 11
to 13 VAC. The voltage will be close to 0
VAC when the valve is not moving.
-
Repeat step 5 across the red
and green leads.
If
any voltage is out of tolerance, replace the
controller. If the above steps pass, inspect for
contamination in the valve or nicks on the seat of
the valve.
CAUTION: If the valve was taken apart and was left
running while taken apart, the piston may have come
too far out of the motor assembly. If you reassemble
the valve with the piston in this position, the
threads in the piston will be stripped when the
piston is forced into the seat while tightening the
lock nut. Make sure the piston is drawn up far
enough into the motor assembly before reassembling.
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|
11.
Pressure transducer troubleshooting |
|
Use
the voltage chart below to determine if there is a
fault with the pressure transducer.
The
green lead is connected to terminal ‘1-‘on the
board. The white lead is connected to terminal ‘1S’
on the board. The black lead is connected to
terminal ‘1+’ on the board. The black wire gets 5
VDC, the white wire is the signal, and the green
wire is the ground. Chart A shows the
characteristics of the pressure transducer. NOTE:
The pressure transducer cannot be repaired but
replaced only.
Pressure Sensor Simulation Values (0 to 150 PSIA)
|
BAR |
PSIA |
PSIG |
V (White to Green) |
|
0 |
0 |
-14.6 |
0.509 |
|
0.69 |
10 |
-4.6 |
0.784 |
|
1.379 |
20 |
5.4 |
1.058 |
|
2.069 |
30 |
15.4 |
1.332 |
|
2.758 |
40 |
25.4 |
1.587 |
|
3.448 |
50 |
35.4 |
1.862 |
|
4.137 |
60 |
45.4 |
2.136 |
|
4.827 |
70 |
55.4 |
2.391 |
|
5.516 |
80 |
65.4 |
2.665 |
|
6.206 |
90 |
75.4 |
2.920 |
|
6.895 |
100 |
85.4 |
3.194 |
|
7.585 |
110 |
95.4 |
3.469 |
|
8.274 |
120 |
105.4 |
3.724 |
Example: If the suction pressure is operating at 15
psig, the voltage across the White and Green wire
should approach 1.332 VDC. If this voltage reading
is out of range, it is likely that the pressure
transducer needs replacing. Also, there is a service
port near the pressure transducer, hook an accurate
low side gauge here and compare to the Pr read out
on the control board. This will give an idea of how
accurate the pressure transducer is responding to
the true suction pressure. |
|
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|
12.
Temperature sensor troubleshooting |
Procedures to check temperature sensor tolerance
with ice water:
-
Use a cup of water with well-stirred ice. The
water temperature should be an even 32°F.
-
Submerge the room temperature sensor (TS3) into
the water while the Master Controller is
normally operating. Check the display for the
value. If the sensor shows 32°F, it is working
properly.
-
Push PB1 and PB2 simultaneously until the green
LED is blinking, scroll down the display to
“in”, the defrost termination sensor (TS1)
value. Submerge the sensor into the water. Check
the display for the value. If the sensor shows
32°F, it is working properly.
-
Scroll down the display to “oU”, the outlet
sensor (TS2) value.
-
Submerge the outlet sensor into the water. Check
the display for the value. Again, if the sensor
shows 32°F, it is working properly.
Compare the temperature and
resistance to the chart below.
Temperature/Resistance Characteristics (-50 to 80
oF)
|
Temp. oF |
Temp. oC |
ohms*1k |
|
Temp. oF |
Temp. oC |
ohms*1k |
|
-50 |
-45.6 |
43.45 |
|
15 |
-9.4 |
7.579 |
|
-40 |
-40.0 |
32.31 |
|
20 |
-6.7 |
6.731 |
|
-35 |
-37.2 |
27.96 |
|
25 |
-3.9 |
5.993 |
|
-30 |
-34.4 |
24.27 |
|
30 |
-1.1 |
5.349 |
|
-25 |
-31.7 |
21.13 |
|
32 |
0 |
5.123 |
|
-20 |
-28.9 |
18.43 |
|
35 |
1.7 |
4.781 |
|
-15 |
-26.1 |
16.12 |
|
40 |
4.4 |
4.281 |
|
-10 |
-23.3 |
14.13 |
|
50 |
10.0 |
3.454 |
|
-5 |
-20.6 |
12.42 |
|
60 |
15.6 |
2.805 |
|
0 |
-17.8 |
10.94 |
|
70 |
21.1 |
2.294 |
|
5 |
-15.0 |
9.651 |
|
80 |
26.7 |
1.888 |
|
10 |
-12.2 |
8.544 |
|
|
|
|
Note: Use resistance at 32°F for sensor
checking.
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