NOTE: The control does not detect circuit breaker failures. If a circuit breaker trips on the lead compressor in a circuit, a low oil pressure failure will be indicated; on the other compressors, no failure will be indicated.
Checkout P~-o~etiur~ (Codes 51-54) - Shut off the main power to the unit. Turn on control power, then step through the Quick Test to the proper compressor number (i.e., failure code S3 is step CBT). Next, energize the step. If the step works correctly, then the failure code is due to:
. HPS open
• Ix-r open
•Mj~placcd fu& back wire from 2H5 strip to 293 strip
•Ground wire and 24-volt feeds reversed on one or more points on 2.t.3. The 24-volt ground wire (brown)jumps terminals 2, 4, 6 and 8. Feeds from compressors Al, A2, Bl and 82 connect to pins I, 3, 5 and 7.
The processor closes the contacts between 255 ter- minals 12 and 
1 I to start the cc3mprwsor. (See Fig. 3.) The safeties shown to the right of 2.15 must be closed for power to reach the compressor c<)ntroX relay (CR 1) and the feedback input (terminal 
t ~I”I 2,13).
Failure of power to terminal 
t OLI 2J3 when contacts 255 
1 I and I2 should be closed wilt cause a code 5 
1 alarm.
Terminal 2 on 293 is the other leg of the compressor Al feedback channel. It is connected to the 24-volt ground.
Code 59 and 60, Loss of Refrigerant Charge ~ A loss-of- charge switch is connected to the high-pressure side of the refrigerant system. The microprocessor monitors this switch directly; if it opens, all the compressors in the circuit will be locked off, the alarm will be energized and the display code will appear when the alarm display is accessed. To reset, use the manual reset method (move the RUN/STANDBY switch to STANDBY, then back to RUN).
Following are some possible causes for this alarm:
f,n\a> RejPigerant Charge - If the system refrigerant charge is very low, the microprocessor will detect this through the switch and indicate the error.
StzYtch Failure - If the switch f&s open, the micro- processor will detect this and indicate an error.
Wiring Error - If there is a wiring error that causes an open circuit, the microprocessor wikk treat this as an open switch and indicate an error.
Proc~esssr Board Failure - If the hardware in the pro- cessor module fails in a manner that the switch cannot be read properly, an error may be indicated.
Code 61, No Cooler Flow - The microprocessor con- tains logic that prutects the cooler against loss of cooler flow.The cooler entering and leaving water temperature sensors are used for this purpose. The leaving thermistor is located in the leaving water nozzle and the entering sensor is located in the first cooler baffle space in close proximity to the cooler tubes as shown in Fig. 4. When there is no cooler water flow and the compressors are operating, the leaving water temperature thermistor will
indicate no temperature change. But the temperature of the entering water will drop rapidly and the entering
water thermistor will detect this. When the entering water temperature drops to 5 F (2.8 C) below the leaving water temperature, alf the compressors will stop and code no. 61 will be displayed. To correct, use manual reset method (after cooler water Row is resumed).
The error will be caused either by no cooler flow or if the water is flowing in the wrong direction through the cooler or if the thermistors have been interchanged.
Fig. 3 - Compressor Al Control Wiring (Typical)
Code 63 and 64, Low Oil Pressure ~~ A low oil pressure switch is installed on the lead compressor in each circuit. If the switch opens during operation of the compressor, all the compressors in the circuit will be shut off, the alarm light will be energized and the appropriate display code shown. The switch will be bypassed for one minute during start-up and for 45 seconds during normal operation. The manual reset method must be used to reset this safety.
Possible causes for failure are:
Loss of’ Oil Pres.sute - If the oil pressure is below 5 & 
1 psig (34.5 & 6.9 kpa), the switch will open.
.S\i’itch Failure - If the switch fails open, a failure will be indicated.
Compwssor is not running.
wiring Errur - If a wiring error exists that causes an open circuit, an error will occur.
Pm~essov Mod& Faifure ~ If the hardware on the processor module fails in a manner that the switch cannot be read properly, an error may be indicated.
Code 65, Cooler Freeze Protection ~ If the leaving water temperature is below 35 F (1.7 C) for a water chiller or is 6’F (3.3 C) below the set point for brine applications, all compressors wiil be stopped. This safety will auto- matically reset when the water temperature is 6 F (3.3 C) above the set point.
The causes for this failure are usually due to low cooler flow, or extremely rapid load changes.
Code 66 and 67, High Suction Superheat - The micro- processor contains the following logrc and ifit is satisfied, all the compressors in the circuit will be stopped:
Suction superheat is greater than 75 F (4f.7 C), and saturated cooler suction is iess than 55 F (12.8 C) and these 2 conditions have been true for more than5 minutes.
To reset this, use the manual reset method. Causes for this failure are:
IL);%’ R<fkigeranf C’hwge ~ A low refrigerant charge will. not allow the correct amount of refrigerant to be fed to the evaporator, which will result in a high superheat.
Pbuggcd F i l t e r Drier - If the liquid line filter drier becomes plugged, it can result in not enough refrigerant being fed to the evaporator, which results in a high super- heat failure.
EXY Failure - If the EXV fails to open enough to feed the proper amount of refrigerant, the error will occur.
EXV Dviveu Moduk Failure ~ Xf the DSIO module hardware that controls the EXVs fails, the valve will not move.
