80
Table 79 — Cooling Service Analysis
LEGEND
PROBLEM
SOLUTION
COMPRESSOR DOES NOT RUN
Active Alarm
Check active alarms using local display.
Contactor Open
1. Power off.
1. Restore power.
2. Fuses blown in field power circuit.
2. After finding cause and correcting, replace with correct size fuse.
3. No control power.
3. Check secondary fuse(s); replace with correct type and size.
Replace transformer if primary windings receiving power.
4. Compressor circuit breaker tripped.
4. Check for excessive compressor current draw. Reset breaker;
replace if defective.
5. Safety device lockout circuit active.
5. Reset lockout circuit at circuit breaker.
6. High-pressure switch open.
6. Check for refrigerant overcharge, obstruction of outdoor airflow, air
in system or whether compressor discharge valve is fully open. Be
sure outdoor fans are operating correctly.
7. Loose electrical connections.
7. Tighten all connections.
Contactor Closed
1. Compressor leads loose.
1. Check connections.
2. Motor windings open.
2. See compressor service literature.
3. Single phasing.
3. Check for blown fuse. Check for loose connection at compressor
terminal.
4. ASTP activated.
4. Allow 30 to 120 minutes for cool down. See Compressor Safeties
section on page 35.
COMPRESSOR STOPS ON HIGH PRESSURE
Outdoor Fan On
1. High-pressure switch faulty.
1. Replace switch.
2. Airflow restricted.
2. Remove obstruction.
3. Air recirculating.
3. Clear airflow area.
4. Noncondensables in system.
4. Purge and recharge as required.
5. Refrigerant overcharge.
5. Purge as required.
6. Line voltage incorrect.
6. Consult power company.
7. Refrigerant system restrictions.
7. Check or replace filter drier, expansion valve, etc. Check that
compressor discharge valve is fully open.
8. Fan running in reverse direction.
8. Correct wiring.
Outdoor Fan Off
1. Fan slips on shaft.
1. Tighten fan hub setscrews.
2. Motor not running.
2. Check power and capacitor.
3. Motor overload open.
3. Check overload rating. Check for fan blade obstruction.
4. Motor burned out.
4. Replace motor.
COMPRESSOR CYCLES ON LOW PRESSURE
Indoor-Air Fan Running
1. Filter drier plugged.
1. Replace filter drier.
2. Expansion valve power head defective.
2. Replace power head.
3. Low refrigerant charge.
3. Add charge.
4. Faulty pressure transducer.
4. Check that pressure transducer is connected and secured to
suction line. If still not functioning, replace transducer.
Airflow Restricted
1. Coil iced up.
1. Check refrigerant charge.
2. Coil dirty.
2. Clean coil fins.
3. Air filters dirty.
3. Clean or replace filters.
4. Dampers closed.
4. Check damper operation and position.
Indoor-Air Fan Stopped
1. Electrical connections loose.
1. Tighten all connections.
2. Fan relay defective.
2. Replace relay.
3. Motor overload open.
3. Power supply.
4. Motor defective.
4. Replace motor.
5. Fan belt broken or slipping.
5. Replace or tighten belt.
COMPRESSOR RUNNING BUT COOLING INSUFFICIENT
Suction Pressure Low
1. Refrigerant charge low.
1. Add refrigerant.
2. Head pressure low.
2. Check refrigerant charge.
3. Air filters dirty.
3. Clean or replace filters.
4. Expansion valve power head defective.
4. Replace power head.
5. Indoor coil partially iced.
5. Check low-pressure setting.
6. Indoor airflow restricted.
6. Remove obstruction.
Suction Pressure High
Heat load excessive.
Check for open doors or windows.
UNIT OPERATES TOO LONG OR CONTINUOUSLY
1. Low refrigerant charge.
1. Add refrigerant
2. Control contacts fused.
2. Replace control.
3. Air in system.
3. Purge and evacuate system.
4. Partially plugged expansion valve or filter drier.
4. Clean or replace.
ASTP —
Advanced Scroll Temperature Protection
VFD
—
Variable Frequency Drive
Summary of Contents for Carrier Weathermaker 48A2
Page 105: ...105 Fig 20 Typical Main Control Box Wiring Schematic 48 50A2 A3 A4 A5 Units...
Page 106: ...106 Fig 21 Typical Auxiliary Control Box Wiring Schematic...
Page 107: ...107 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown a48 8357...
Page 108: ...108 TO NEXT PAGE Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown A48 7296...
Page 109: ...109 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont A48 8358...
Page 110: ...110 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown a50 8228...
Page 111: ...111 Fig 25 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown...
Page 112: ...112 Fig 26 Typical Low Ambient Controls Option Wiring...
Page 113: ...113 Fig 27 Typical Small Chassis Component Location Size 020 035 Units...
Page 114: ...114 Fig 28 Typical Large Chassis Component Locations Size 040 060 Units...
Page 118: ...118 Fig 30 Economizer Control Board ECB1 and VAV Control Board ECB2 A48 7706...
Page 142: ...142 A48 3733 Fig 56 Main Burner Removal...
Page 176: ...176 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716...
