SECTION 9 – SERVICE AND TROUBLESHOOTING
FORM QWC3-NM1
ISSUE DATE:11/20/2020
QUANTECH
163
9
TROUBLESHOOTING
TABLE 26 - 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 TB1 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 & IO
board to isolate.
5. Defective IPU II & I/O board or
Display board.
5. Replace IPU II & IO board or the
Display Board.
Contact
Quantech Sales
Representative
before replacing
circuit boards.
FLOW SWITCH/REM
STOP NO RUN PERMISSIVE
1. No chilled liquid ow. 1. Check chilled liquid ow.
2. Flow switch improperly installed. 2. Check that the ow switch is
installed according to manufacturer’s
instructions.
3. Defective ow switch. 3. Replace ow 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. Improper suction pressure cutout
adjustments.
1. Adjust per recommended 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 ow of chilled liquid
through the cooler.
5. Check GPM (See Limitations in
SECTION 4 - INSTALLATION).
Check operation of pump, clean
pump strainer, purge chilled liquid
system of air.
6. Defective suction pressure
transducer/low pressure switch or
wiring.
6. Replace transducer/low pressure
switch or faulty wiring. See the
Service section for pressure /
voltage formula.
7. LLSV defective. 7. Replace LLSV.
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