Quantech QCC2015CEE Installation, Operation And Maintenance Manual page 150

SECTION 9 – SERVICE AND TROUBLESHOOTING
Table 30 - Troubleshooting
PROBLEM
NO DISPLAY ON PANEL. UNIT
WILL NOT OPERATE.
FLOW SWITCH/REM STOP NO
RUN PERMISSIVE
LOW SUCTION PRESSURE
FAULT
HIGH DISCHARGE PRESSURE
FAULT
150
Troubleshooting
CAUSE
1. No 115VAC to 24 VAC
Transformer.
2. No 24VAC to Microboard.
3. Control Transformer defective,
no 24VAC output.
4. Short in wire to temp. sensors or
pressure transducers.
5. Defective IPU II and I/O Board or
the Display Board.
1. No air flow.
2. Air Proving switch incorrectly
installed.
3. Defective Air Proving switch.
4. Remote cycling device open.
1. Incorrect suction pressure
cutouts adjustments.
2. Low refrigerant charge.
3. Fouled filter dryer.
4. TXV defective.
5. Reduced air flow
6. Defective suction pressure
transducer/low pressure switch
or wiring.
7. LLSV defective
1. Condenser fans not operating or
operating backwards.
2. Too much refrigerant.
3. Air in refrigerant system.
4. Defective discharge pressure
transducer.
SOLUTION
1a. Check wiring and fuse 1FU.
1b. Check wiring emergency stop contacts 5 to
L of XTBC2 Terminal Block.
1c. Replace Control Transformer.
2. Check wiring Control Transformer to
Microboard.
3. Replace Control Transformer.
4. Unplug connections at IPU II and I/O Board
to isolate.
5. Replace IPU II and I/O Board or the Display
Board.
Contact Quantech Service Rep-
resentative before replacing
circuit Boards!
1. Check air flow.
2. Check that the Air Proving switch is installed
according to manufacturer's instructions.
3. Replace Air Proving switch.
4. Check cycling devices connected to
terminals 13 and 14 of the XTBC1 Terminal
Block.
1. Adjust per recommended settings.
2. Repair leak if necessary and add refrigerant.
3. Change dryer/core.
4. Replace TXV.
5. Check air flow
6. Replace transducer/low pressure switch
or faulty switch or wiring. Refer to Service
section for pressure/voltage formula.
7. Replace LLSV
1. Check fan motor, and contactors. Ensure fan
blows air upward.
2. Remove refrigerant.
3. Evacuate and recharge system.
4. Replace discharge pressure transducer.
Refer to Service section for pressure/voltage
formula.
Form QCC2-NM1
Issue Date: 5/20/2021
QUANTECH