1. Leak Detection All Refrigerant: Soap bubble
Ultrasonic : 0.05mm hole , 14 m range
Pressure : by makers

2. Leak Detection Halogenated Refrigerant: Halide lamp Electronic
pale blue to green to violet
Electronic
all except R14 –
very sensitive –measures resistance of vapour
confined to production work
affected by carbon monoxide and alcohol

3. Leak Detection Ammonia Sulphur candle / sulphur dioxide (cans)
white cloud of ammonia sulphate
Hydrochloric acid
white cloud ammonia chloride
Litmus paper
difficult if leak’s major

4. Indication of leakage Oil weeping from joints/connections
Low level / large bubbles in sight glass
Low suction pressure
High superheat
Continuous running
Difficult to maintain temperature
Odour – in ammonia plant

5. Sudden efficiency drop (causes)
Refrigeration loss
Broken valves
Icing up of TX valves
Belt slipping

6. Short Cycling on H.P. (causes)
Condenser cooling
Fouled condenser
Overcharging
Air in system
Wrong adjustment of switch

7. Short Cycling on L.P. (causes)
Frosted evaporator coils
Choked strainer/drier
Leaky discharge valves
Defective TX valves; wrong orifice
Under charge
Wrong adjustment of switch

8. Poor cooling in condenser (causes)
Cooling water
High H.P.
Reading incorrect
Pump fault
Choked strainer
Fouled condenser
High S.W.. temperature

9. Undercharge (symptoms)
Large bubbles in sight glass
Low discharge pressure
Low suction pressure
Prolong running
Less frosting on suction
Performance drop
Action : Leak test, rectify and recharge

10. Overcharge (symptoms)
Sight glass full
High discharge pressure
Cut out on H.P.
More frosting on suction
Action: pump to condenser and use recovery system to release

11. Liquid at suction( symptoms)
Crankcase frosting
Oil loss
Noise
High H.P.

12. Moisture (symptoms) Inlet to TX frosting Drier frosting up
Low suction pressure
Action: renew drier until all moisture removed.

13. Coil Frosting (effect)
Runs longer
Short cycling on L.P.
Drop in performance
Action : defrost

14. Contaminants Oil Reduces heat transfer Oil separator
more at low temperature
Oil separator
Ammonia not miscible
condenser drains

15. Contaminants Water Ice in low temperature region Corrosion
Copper plating ; staining of valve plates, etc
Electrical Insulation breakdown
Driers / Anti-freeze
15ppm (R12) ; 25ppm(R22) during manufacture
Vacuum after repair

16. Contaminants Air / non-condensable gases Increase pr Noisy compressor
Performance drop
Bubbles in sight glass
Compare pressure with saturated vapour pressure
Purge from condenser

17. Contaminants Copper plating When moisture is present
Copper picked up by Freon
Deposit on liners, piston , valves etc

18. Operational Faults Loss of oil from crankcase
Suction pressure drop suddenly
during start up
load reduction
Liquid Freon evaporates
Foaming – leading to oil carried away

19. Operational faults Excessive oil
Collect in coils - reduce heat transfer
Low suction pressure , noisy compressor

20. Operational Faults To prevent damage due to oil loss
Minimise pressure fluctuation
Suitable TX valve
Use de-foaming agent
Pump down if long shut-down
Ensure oil returned from system
No condensed liquid from evaporator during shut-down

21. TX valve problem TX valve strainer clogged Remote bulb
dislodged
check by cooling and warming
If oversize: overfeeding at part load
If undersize: overloaded at full load