York SUNLINE DCG Series Installation Manual

Contents

York SUNLINE DCG Series Installation Manual Manual pdf 49 page image

290699-YIM-B-0607Unitary Products Group 49tion, check the room thermostat for contact betweenR and G in the AUTO position during calls for cooling.3. If the supply air blower motor does not energizewhen the fan switch is set to ON, check that linevoltage is being supplied to the contacts of the M2,contactor, and that the contactor is pulled in. Checkfor loose wiring between the contactor and the sup-ply air blower motor.4. If M2 is pulled in and voltage is supplied to M2,lightly touch the supply air blower motor housing. Ifit is hot, the motor may be off on internal protec-tion. Cancel any thermostat calls and set the fanswitch to AUTO. Wait for the internal overload toreset. Test again when cool.5. If M2 is not pulled in, check for 24 volts at the M2coil. If 24 volts are present at M2 but M2 is notpulled in, replace the contactor.6. Failing the above, if there is line voltage supplied atM2, M2 is pulled in, and the supply air blowermotor still does not operate, replace the motor.7. If 24 volts is not present at M2, check that 24 voltsis present at the UCB supply air blower motor ter-minal, “FAN”. If 24 volts is present at the FAN,check for loose wiring between the UCB and M2.8. If 24 volts is not present at the “FAN” terminal,check for 24 volts from the room thermostat. If 24volts are not present from the room thermostat,check for the following:a. Proper operation of the room thermostat (contactbetween R and G with the fan switch in the ON posi-tion and in the AUTO position during operationcalls).b. Proper wiring between the room thermostat and theUCB.c. Loose wiring from the room thermostat to the UCB.9. If 24 volts is present at the room thermostat but notat the UCB, check for proper wiring between thethermostat and the UCB, i.e. that the thermostat Gterminal is connected to the G terminal of the UCB,and for loose wiring.10. If the thermostat and UCB are properly wired,replace the UCB.On a call for cooling, the supply air blower motor isoperating but the compressor is not (the room thermo-stat fan switch is in the “AUTO” position).1. If installed, check the position of the economizerblades. If the blades are open, the economizer isproviding free cooling and the compressors will notimmediately operate. If both stages of cooling arerequested simultaneously and the economizer pro-vides free cooling, following a short delay the com-pressor will be energized unless it is locked out,unless this option has been disabled through com-puter communications.2. If no economizer is installed or the economizer is notopening to provide free cooling and the compressordoes not energize on a call for cooling, check for linevoltage at the compressor contactor, M1, and thatthe contactor is pulled in. Check for loose wiringbetween the contactor and the compressor.3. If M1 is pulled in and voltage is supplied at M1,lightly touch the compressor housing. If it is hot, thecompressor may be off on inherent protection.Cancel any calls for cooling and wait for the inter-nal overload to reset. Test again when cool.4. If M1 is not pulled in, check for 24 volts at the M1coil. If 24 volts are present and M1 is not pulled in,replace the contactor.5. Failing the above, if voltage is supplied at M1, M1is pulled in, and the compressor still does not oper-ate, replace the compressor.6. If 24 volts is not present at M1, check for 24 volts atthe UCB terminal, C1. If 24 volts is present, checkfor loose wiring between C1 and the compressorcontactor.7. If 24 volts is not present at the C1 terminal, checkfor 24 volts from the room thermostat at the UCBY1 terminal. If 24 volts is not present from the roomthermostat, check for the following:a. 24 volts at the thermostat Y1 terminalb. Proper wiring between the room thermostat and theUCB, i.e. Y1 to Y1, Y2 to Y2c. Loose wiring from the room thermostat to the UCB.8. If 24 volts is present at the UCB Y1 terminal, thecompressor may be out due to an open high-pres-sure switch, low-pressure switch, or freezestat.Check for 24 volts at the HPS1, LPS1, and FS1terminals of the UCB. If a switch has opened, thereshould be a voltage potential between the UCB ter-minals, e.g. if LPS1 has opened, there will be a 24-volt potential between the LPS1 terminals.9. If 24 volts is present at the UCB Y1 terminal andnone of the protection switches have opened, theUCB may have locked out the compressor for repeattrips. The UCB should be flashing an alarm code. Ifnot, press and release the ALARMS button on theUCB. The UCB will flash the last five alarms on theLED. If the compressor is locked out, cancel any callfor cooling. This will reset any compressor lock outs.