York YLAA0195HE, Manual, Page: 187 / 206

187
JOHNSON CONTROLS
FORM 150.72-NM3 (1020)
ISSUE DATE 10/05/2020
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,
PRESSURE” FAULT or operating backwards. and contactors. Assure 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. Micropanel 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
(assure 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)