York Predator MagnaDRY DR090 Series Installation Manual

Also see for PREDATOR MagnaDRY DR090: Technical guide Installation manual

264276-XIM-B-1208Johnson Controls Unitary Products 5711. If 24 volts is present at the UCB Y1 terminal and thecompressor is not out due to a protective switch trip,repeat trip lock out, or ASCD, the economizer terminalsof the UCB may be improperly wired. Check for 24 voltsat the Y1 “OUT” terminal of the UCB. If 24 volts ispresent, trace the wiring from Y1 “OUT” for incorrectwiring. If 24 volts is not present at the Y1 “OUT”terminal, the UCB must be replaced.12. For units without economizers: If 24 volts is present atthe Y1 “OUT” terminal, check for 24 volts at the Y1“ECON” terminal. If 24 volts is not present, check forloose wiring from the Y1 “OUT” terminal to the Mate-N-Lock plug, the jumper in the Mate-N-Lock plug, and inthe wiring from the Mate-N-Lock plug to the Y1 “ECON”terminal.For units with economizers:If 24 volts is present at theY1 “OUT” terminal, check for 24 volts at the Y1 “ECON”terminal. If 24 volts is not present, check for loose wiringfrom the Y1 “OUT” terminal to the Mate-N-Lock plug, apoor connection between the UCB and economizerMate-N-Lock plugs, loose wiring from the Mate-N-Lockplug to the economizer, back to the Mate-N-Lock plug,and from the Mate-N-Lock plug to the Y1 “ECON”terminal. The economizer control may have faulted andis not returning the 24 volts to the Y1 “ECON” terminaleven though the economizer is not providing freecooling. To test the economizer control, disconnect theMate-N-Locks and jumper between the WHITE andYELLOW wires of the UCB’s Mate-N-Lock plug.13. The UCB can be programmed to lock out compressoroperation during free cooling and in low ambient condi-tions. These options are not enabled by default. Theycan be checked by local distributors.For units with factory installed economizers, the UCB isprogrammed to lock out compressor operation when theLAS set point is reached.For units without factory installed or with field installedeconomizers, the UCB allows compressor operation allthe time. This programming can be checked or changedby the local distributor.14. If none of the above corrected the error, test the integrityof the UCB. Disconnect the C1 terminal wire and jumperit to the Y1 terminal. DO NOT jump the Y1 to C1 termi-nals. If the compressor engages, the UCB has faulted.15. If none of the above correct the error, replace the UCB.GAS HEAT TROUBLESHOOTING GUIDEOn calls for heating, the draft motor operates and the furnacelights but the supply air blower motor does not energize aftera short delay (the room thermostat fan switch is in “AUTO”position).1. Place the thermostat fan switch in the “ON” position. Ifthe supply air blower motor energizes, go to Step 9.2. If the supply air blower motor does not energize whenthe fan switch is set to “ON,” check that line voltage isbeing supplied to the contacts of the M3 contactor, andthat the contactor is pulled in. Check for loose wiringbetween the contactor and the supply air blower motor.3. If M3 is pulled in and voltage is supplied at M3, lightlytouch the supply air blower motor housing. If it is hot, themotor may be off on inherent protection. Cancel anythermostat calls and set the fan switch to “AUTO”, waitfor the internal overload to reset. Test again when cool.4. If M3 is not pulled in, check for 24 volts at the M3 coil. If24 volts is present at M3 but M3 is not pulled in, replacethe contactor.5. Failing the above, if there is line voltage supplied at M3,M3 is pulled in, and the supply air blower motor still doesnot operate, replace the motor.6. If 24 volts is not present at M3, check that 24 volts ispresent at the supply air blower motor terminal on theUCB. If 24 volts is present at the UCB terminal, checkfor loose wiring between the UCB and M3.a. If 24 volts is not present at the UCB supply airblower motor terminal, check for 24 volts from theroom thermostat. If 24 volts is not present from theroom thermostat, check for the following:i. Proper operation of the room thermostat (con-tact between R and G with the fan switch in the“ON” position and in the “AUTO” position duringoperation calls)ii. Proper wiring between the room thermostat andthe UCB, andiii. Loose wiring from the room thermostat to theUCB7. If 24 volts is present at the room thermostat but not at theUCB, check for proper wiring between the thermostatand the UCB, i.e. that the thermostat G terminal is con-nected to the G terminal of the UCB, and for loose wir-ing.8. If the thermostat and UCB are properly wired, replacethe UCB.The furnace may shut down on a high temperaturecondition during the procedure. If this occurs, theUCB energize the supply air blower motor until thehigh temperature limit has reset. Caution should beused at all times as the supply air blower may ener-gize regardless of the room thermostat fan switchposition.

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