Quantech QCC2015CEE, Installation, Operation And Maintenance Manual, Page: 150 / 172

QUANTECH
150
Form QCC2-NM1
Issue Date: 5/20/2021
SECTION 9 – SERVICE AND TROUBLESHOOTING
Troubleshooting
Table 30 - Troubleshooting
PROBLEM CAUSE SOLUTION
NO DISPLAY ON PANEL. UNIT
WILL NOT OPERATE.
1. No 115VAC to 24 VAC
Transformer.
1a. Check wiring and fuse 1FU.
1b. Check wiring emergency stop contacts 5 to
L of XTBC2 Terminal Block.
1c. Replace Control Transformer.
2. No 24VAC to Microboard. 2. Check wiring Control Transformer to
Microboard.
3. Control Transformer defective,
no 24VAC 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 Quantech Service Rep-
resentative before replacing
circuit Boards!
FLOW SWITCH/REM STOP NO
RUN PERMISSIVE
1. No air flow. 1. Check air flow.
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 XTBC1 Terminal
Block.
LOW SUCTION PRESSURE
FAULT
1. Incorrect suction pressure
cutouts adjustments.
1. Adjust per recommended settings.
2. Low refrigerant charge. 2. Repair leak if necessary and add refrigerant.
3. Fouled filter dryer. 3. Change dryer/core.
4. TXV defective. 4. Replace TXV.
5. Reduced air flow 5. Check air flow
6. Defective suction pressure
transducer/low pressure switch
or wiring.
6. Replace transducer/low pressure switch
or faulty switch or wiring.
Refer to 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.
Refer to Service section for pressure/voltage
formula.