Daikin McQuay AGZ-D 25, Operating And Maintenance Manual

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IMM 1078 AGZ 030C through 190C 80
AGZ-D Troubleshooting Chart
PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS
Compressor Will
Not Run
1. Main switch. 1. Close switch.
2. Fuse blown. circuit breakers open
2. Check electrical circuits and motor windings for
shorts or grounds. Investigate for possible overloading.
Replace fuse or reset breakers after fault is corrected.
Check for loose or corroded connections.
3. Thermal overloads tripped
3. Overloads are auto-reset. Check unit closely when
unit comes back on line. Allow time for auto-reset.
4. Defective contactor or coil. 4. Repair or replace
5. System shutdown by equipment protection devices
5. Determine type and cause of shutdown and correct
it before resetting equipment protection switch.
6. No cooling required 6. None. Wait until unit calls for cooling.
7. Liquid line solenoid will not open 7. Repair or replace solenoid coil. Check wiring.
8. Motor electrical trouble 8. Check motor for opens, shorts, or burnout.
9. Loose wiring 9. Check all wire junctions. Tighten all terminal screws.
Compressor
Noisy Or Vibrating
1. Low or no refrigerant charge
2. Compressor running in reverse
3. Improper piping support on suction or discharge
4. Worn compressor isolator bushing
5. Worn Compressor
1. Repair and recharge
2. Check unit and compressor for correct phasing
3. Relocate, add, or remove hangers
4. Replace
5. Replace
High Discharge
Pressure
1. Noncondensables in system
1. Extract the noncondensables with approved
procedures.
2. System overcharged with refrigerant 2. Remove excess, check liquid subcooling.
3. Optional discharge shutoff valve partially closed 3. Open valve.
4. FanTrol wiring not correct 4. Check FanTrol wiring.
5. Fan not running 5. Check electrical circuit, Check fan motor.
6. Dirty condenser coil
7. Air recirculation
6. Clean coil.
7. Correct.
Low Discharge
Pressure
1. Refrigerant flood back 1. Correct.
2. Wind blowing into coil at low ambient
2. Shield coil from direct wind, Wind guards are
available.
3. Faulty condenser temperature regulation 3. Check condenser control operation.
4. Insufficient refrigerant in system
5. Low suction pressure
4. Check for leaks. Repair and add charge.
5. See corrective steps for Low Suction Pressure.
6. Only one compressor operating
6. See corrective steps for Compressor Will Not Stage
Up.
High Suction
Pressure
1. Excessive water temperature 1. Check control settings.
2. Excessive load 2. Reduce load or add additional equipment.
3. Expansion valve overfeeding 3. Check remote bulb. Regulate superheat.
4. Compressors running in reverse 4. Check for proper phasing.
Low Suction
Pressure
1. Rapid load swings 1. Stabilize load.
2. Lack of refrigerant
2. Check for leaks, repair, add charge. Check liquid
sight glass.
3. Clogged liquid line filter drier 3. Check pressure drop across filter drier. Replace.
4. Expansion valve malfunctioning 4. Check and reset for proper superheat.
5. Condensing temperature too low
5. Check means for regulating condenser
temperature.
6. Compressor will not unload
6. See corrective steps for Compressor Staging
Intervals Too Low.
7. Insufficient water flow 7. Adjust flow.
8. Evaporator head ring gasket slippage
8. Take pressure drop across vessel and contact
factory to obtain design pressure drop for that vessel.
9. Evaporator dirty
10. Rapid load swings
9. Clean chemically.
10. Stabilize load.
Compressor Will
Not Stage Up
1. Defective capacity control 1. Replace.
2. Faulty thermostat stage or broken wire 2. Replace.
3. Stages not set for application 3. Reset thermostat setting for application.
Compressor
Staging Intervals
Too Short
1. Thermostat control band not set properly 1. Set control band wider.
2. Faulty water temperature sensor 2. Replace.
3. Insufficient water flow
4. Rapid load swings
3. Adjust flow.
4. Stabilize load.