FORM 150.66-NM2
ISSUE DATE: 09/25/2020
153
JOHNSON CONTROLS
SECTION 9 - SERVICE AND TROUBlEShOOTING
9
PROBLEM
CAUSE
SOLUTION
“LOW SUCTION PRESSURE”
4. TXV defective.
4. Replace TXV.
FAULT (CONT’D)
5. Reduced flow of chilled
5. Check GPM
(See “Limita
tions” liquid through the
cooler in Installation section).
Check operation of pump,
clean pump strainer, purge
chilled liquid system of air.
6. Defective suction pressure
6. Replace transducer/low
transducer/low pressure
pressure switch or faulty
switch or wiring.
wiring.
Refer to “Service”
section for pressure/voltage
formula.
7. llSV defective
7. Replace llSV
“HIGH DISCHARGE
1. Condenser fans not operating
1. Check fan motor, fuses,
PRESSURE” FAULT
or operating backwards.
and contactors. Ensure fan
blows air upward.
2. Too much refrigerant.
2. Remove refrigerant.
3. Air in refrigerant system.
3. Evacuate and recharge
system.
4. Defective discharge
4. Replace discharge pressure
pressure
transducer.
transducer.
Refer to Service
section for pressure/voltage
formula.
“LOW LIQUID TEMP”
1. Improperly adjusted leaving
1. Re-program the leaving
FAULT
chilled liquid temp. cutout
chilled liquid temp. cutout.
(glycol only).
2. Micro panel setpoint/range
2. Re-adjust setpoint/range.
values improperly programmed.
3. Chilled liquid flow too low.
3. Increase chilled liquid flow -
refer to Limitations in Instal-
lation section.
4. Defective lWT or RWT sensor
4. Compare sensor against a
(ensure the sensor is properly
known good temperature
installed in the bottom of the well
sensing device.
Refer to
with a generous amount of heat)
Service section for temp./
conductive compound).
voltage table.
CONT’D
TROUBLESHOOTING (CONT’D)
Summary of Contents for YCAL0012EC
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