JOHNSON CONTROLS
31
FORM 160.77-O1
ISSUE DATE: 10/22/2020
SECTION 4 - TROUBLESHOOTING
If the system is malfunctioning in any manner, refer to
the Operation Analywsis Chart shown in
Table 4
. After
consulting these references, if you are unable to make
the proper repairs or adjustments to start the compres-
sor or the particular trouble continues to hinder the
performance of the unit, please call the nearest John-
son Controls District Office. Failure to report constant
troubles could damage the unit and increase the cost of
repairs. If the system shuts down on a safety fault, refer
to the control panel operating manual Form 160.77-O2
or contact JCI Service.
TABLE 3 -
OPERATION ANALYSIS CHART
SYMPTOM
RESULTS
POSSIBLE CAUSE
REMEDY
Abnormally High
Discharge
Pressure
Temperature difference between
condensing temperature and water off
condenser higher than normal.
Air in condenser.
Condenser tubes dirty or
scaled
Clean condenser tubes.
Check water conditioning.
High discharge pressure.
High condenser water tem-
perature.
Reduce condenser water
inlet temperature. (Check
cooling tower and water
circulation.)
Temperature difference between con
-
denser water on and water off higher
than normal, with normal evaporator
pressure.
Insufficient condensing water
flow.
Increase the quantity of water
through the condenser to
proper value.
Abnormally Low
Suction Pressure
Temperature difference between leaving
chilled water and refrigerant in evapo-
rator greater than normal with high
discharge temperature.
Insufficient charge of refriger
-
ant.
Check for leaks and charge
refrigerant into system.
Variable orifice problem.
Remove obstruction.
Temperature difference between leav
-
ing chilled water and refrigerant in the
evaporator greater than normal with
normal discharge temperature.
Evaporator tubes dirty or
restricted.
Clean evaporator tubes.
Temperature of chilled water too low
with low motor amperes.
Insufficient load for system
capacity.
Check prerotation vane mo-
tor operation and setting of
controls.
High Evaporator
Pressure
High chilled water temperature.
Prerotation vanes fail to
open.
Check the prerotation vane
motor positioning circuit.
System overload.
Be sure the vanes are wide
open (without overloading
the motor) until the load
decreases.
No Oil Pressure
When System
Start Button
Pushed
Low oil pressure displayed on control
center; compressor will not start.
Oil pump running in wrong
direction.
Check rotation of oil pump
(Electrical Connections).
Oil pump not running.
Troubleshoot electrical prob-
lem with oil pump VSD.
Unusually High Oil
Pressure Develops
When Oil Pump
Runs
Unusually high oil pressure is displayed
when the oil pressure display key is
pressed when the oil pump is running.
High oil pressure. Transducer
defective.
Replace low or high oil pres-
sure transducer.
4
