CHAPTER 12 MECHANICAL TROUBLESHOOTING TROUBLESHOOTING THE PROCESS OF

CHAPTER 12 MECHANICAL TROUBLESHOOTING

TROUBLESHOOTING • THE PROCESS OF DETERMINIG THE ROOT CAUSE OF AN EQUIPMENT MALFUNCTION & PERFORMING CORRECTIVE ACTIONS • THREE TYPES OF MALFUNCTIONS: • ELECTRICAL • MECHANICAL • COMBINATION

HOW TO TROUBLESHOOT • LOGICAL, STRUCTURED, SYSTEMATIC APPROACH IS BEST • THIS INSURES THE CORRECT SOLUTION IS FOUND IN THE SHORTEST POSSIBLE TIME • EACH TECH WILL DEVELOP HIS/HER OWN METHOD IN TIME WITH EXPERIENCE

STEPS TO EFFICIENT MECHANICAL REFRIGERATION TROUBLESHOOTING 1. COLLECT INFORMATION ABOUT THE PROBLEM A. B. C. D. WHEN CALL RECEIVED FROM CUSTOMER ONSITE VISUAL INSPECTION PRELIMINARY POWER-ON INSPECTION

STEPS - CONTINUED 2. READ & CALCULATE [APPROXIMATE] REFRIGERATION SYSTEM INDICATORS A. B. C. D. SH SC TD E DELTA T

STEPS - CONTINUED 3. COMPARE TYPICAL TO ACTUAL INDICATORS A. DETERMINE EFFICIENCY & TYPICAL VALUES B. COMPARE THAT TO ACTUAL VALUES

STEPS - CONTINUED 4. DETERMINE ROOT CAUSE OF MALFUNCTION A. CONSULT TROUBLESHOOTING AIDS B. USE MANUFACTURER’S AIDS

PRACTICING PROFESSIONAL SERVICES • TROUBLESHOOTING REQUIRES PAITENCE & PERSERVERENCE • DON’T RUSH TO JUDGEMENT • BE SURE TO LOCATE THE ROOT CAUSE- NOT JUST THE SYMPTOM!!! • EX: FLOODBACK CAN CAUSE COMPRESSOR BEARING FAILURE

TROUBLESHOOTING COMPRESSOR • COMPRESSORS ARE DESIGNED TO PROVIDE MANY YEARS OF TROUBLEFREE OPERATION • • COILS KEPT CLEAN FILTERS CHANGED REGULARLY SYSTEM PROPERLY CHARGED ELECTRICAL CURRENT SUPPLY DEPENDABLE

LOSS OF EFFICIENCY • BROKEN VALVES ARE ALMOST ALWAYS CAUSED BY SLUGGING OR MIGRATION • RESULTS IN: • LOW DISCHARGE PRESSURE • HIGH SUCTION PRESSURE • LOW AMP DRAW

MOTOR OVERLOADING • HIGH DISCHARGE PRESSURES • LOW VOLTAGE • MECHANICAL PROBLEMS- WORN OR BURNED BEARINGS

NOISY OPERATION • LIQUID SLUGGING- CURRENTLY OR PAST • OIL SLUGGING- TRAPPED OIL COMING BACK IN LARGE AMOUNTS • COMPRESSOR MOUNTING NUTS TOO TIGHT • HIGH HEAD PRESSURE CAN CAUSE LOUD NOISE WHEN COMPRESSOR STOPS

INTERNAL COMPRESSOR NOISES • INSUFFICIENT LUBRICATION • EXCESSIVE OIL LEVEL • TIGHT PISTON OR BEARING • DEFECTIVE INTERNAL MOUNTING- BROKEN SPRING • LOOSE BEARINGS • BROKEN VALVES • GAS PULSATION – DUE TO LOW EVAP. PRESSURE

ANALYSIS OF DEAD COMPRESSOR 1. 2. 3. 4. 5. 6. 7. 8. 9. OPEN CONTACTOR CONTACTS OVERLOAD OPEN BAD CONNECTIONS LOW REFRIGERANT LOW VOLTAGE CAPACITORS BAD RELAY BAD HIGH HEAD PRESSURE RESTRICTION

TROUBLESHOOTING EVAPORATORS 1. 2. 3. 4. 5. LOW AIR FLOW EXCESSIVE AIR FLOW UNEVEN AIRFLOW REFRIGERANT UNEVEN DISTRIBUTION- DISTRIBUTOR

TROUBLESHOOTING CONDENSERS 1. 2. 3. 4. 5. 6. DIRTY COIL FAN NOT IN POSITION LOW AA RESTRICTION OVERCHARGE UNDERCHARGE

TROUBLESHOOTING METERING DEVICE 1. OVERFEEDING 1. ORIFICE TOO BIG 2. TXV BULB LOOSE 3. OVERCHARGE 2. UNDERFEEDING 1. 2. 3. 4. ORIFICE TOO SMALL TXV BULB LOST CHARGE UNDERCHARGE RESTRICTION 3. TXV HUNTING- TXV TOO BIG 4. DISTRIBUTOR UNEVENLY FEEDING

RESTRICTIONS 1. CAUSES ALL PRESSURES TO GO DOWNREFRIGERANT COLLECTS IN CONDENSER & COOLS TO AA TEMP 2. MIGHT BE FOUND BY CHECKING TEMP DROP 3. DRIER 4. LL

INSTALLATION PROBLEMS 1. 2. 3. 4. 5. 6. LOCATION OF EQUIPMENT LEVELING OF EQUIPMENT- CONDENSATE & OIL ELECTRICAL CONNECTIONS ACCESSORIES- HUMIDIFIER, ECT DUCTWORK SIZING & INSTALLATION NECESSARY MAINTENANCE