Specifications

JOHNSON CONTROLS
166
FORM 150.72-NM1 (908)
Service and Troubleshooting
TROUBLESHOOTING
PROBLEM CAUSE SOLUTION
No display on panel. 1. No 115VAC to 24 VAC 1a. Check wiring and fuse
Unit will not operate. Transformer 1FU
b. Check wiring emergency
stop contacts 5 to L of XTBC2
Terminal Block.
c. Replace Control Transformer
2. No 24VAC to Microboard 2. Check wiring Control
Transformer to Microboard.
3. Control Transformer defective, no 3. Replace Control Transformer
24VAC output.
4. Short in wire to temp. sensors 4. Unplug connections at IPU II
or pressure transducers. & I/O Board to isolate.
5. Defective IPU II & I/O Board 5. Replace IPU II & I/O Board
or the Display Board. or the Display Board.

 
 
 
“FLOW SWITCH/REM 1. No chilled liquid ow. 1. Check chilled liquid ow.
STOP NO RUN PERMISSIVE”
2. Flow switch improperly 2. Check that the ow switch
installed. 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 XTBC1
Terminal Block.
“LOW SUCTION PRESSURE” 1. Improper suction pressure 1. Adjust per recommended
FAULT cutouts adjustments. settings.
2. Low refrigerant charge. 2. Repair leak if necessary
and add refrigerant.
3. Fouled lter dryer. 3. Change dryer/core.
TABLE 27 – TROUBLESHOOTING
CONT’D