York YCUL0055EE User Manual

JOHNSON CONTROLS
156
Form 150.63-NM9
Issue date: 5/20/2021
SECTION 9 – SERVICE AND TROUBLESHOOTING
Troubleshooting
Table 31 - Troubleshooting
PROBLEM CAUSE SOLUTION
NO DISPLAY ON PANEL. UNIT
WILL NOT OPERATE.
1. No 115 VAC to 24 VAC
Transformer.
1a. Check wiring and fuse 1FU.
1b. Check wiring emergency stop contacts 5 to
L of TB1 Terminal Block.
1c. Replace Control Transformer.
2. No 24 VAC to Microboard. 2. Check wiring Control Transformer to
Microboard.
3. Control Transformer defective,
no 24 VAC output.
3. Replace Control Transformer.
4. Short in wire to temp. sensors or
pressure transducers.
4. Unplug connections at IPU II and I/O Board
to isolate.
5. Defective IPU II and I/O Board or
the Display Board.
5. Replace IPU II and I/O Board or the Display
Board.
Contact Johnson Controls
Service before replacing circuit
Boards!
FLOW SWITCH/REM STOP NO
RUN PERMISSIVE
1. No air ow. 1. Check air ow.
2. Air Proving switch incorrectly
installed.
2. Check that the Air Proving switch is installed
according to manufacturer’s instructions.
3. Defective Air Proving switch. 3. Replace Air Proving switch.
4. Remote cycling device open. 4. Check cycling devices connected to
terminals 13 and 14 of the CTB1 Terminal
Block.
LOW SUCTION PRESSURE
FAULT
1. Improbeforesuction pressure
cutouts adjustments.
1. Adjust beforerecommended settings.
2. Low refrigerant charge. 2. Repair leak if necessary and add refrigerant.
3. Fouled lter dryer. 3. Change dryer/core.
4. TXV defective. 4. Replace TXV.
5. Reduced air ow 5. Check air ow
6. Defective suction pressure
transducer/low pressure switch
or wiring.
6. Replace transducer/low pressure switch or
faulty switch or wiring. See Service section
for pressure/voltage formula.
7. LLSV defective 7. Replace LLSV
HIGH DISCHARGE PRESSURE
FAULT
1. Condenser fans not operating or
operating backwards.
1. Check fan motor, 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 pressure
transducer.
4. Replace discharge pressure transducer. See
Service section for pressure/voltage formula.

York YCUL0055EE Specifications

General

Brand	York
Model	YCUL0055EE
Category	Heat Pump
Language	English