Collection of various types of faults and troubleshooting methods for central air-conditioning!(Ⅱ)

During operation, the fan motor overheated

During operation, the fan motor overheated

1. Install at the correct angle

2. Replace

3. Disassembly and cleaning

4. Come on

5. Replace after inspection

6. Use high temperature motor

7. Measure the voltage to find out the cause

8. Replace

9. Fasten the terminals

During operation, the cooling water pump sucks in air

1. Lower water level in the sink below

2. The filter is blocked

1. Find out the cause and replenish water

2. Cleaning

The filling material is polluted, and the circulating water is also polluted

1. Inhale the smoke

2. Inhale the polluted air around

3. Poor effect of water treatment device

1. Move the cooling tower or eliminate the flue gas

2. Eliminate environmental pollution

3. Repair water treatment equipment

Condenser type

advantage

Disadvantage

Scope of use

Water-cooled

1. Vertical shell and tube type

2. Horizontal shell and tube type

3. Casing type

4. Immersive

1) It can be installed outdoors in the sky, saving the area of the computer room

2) Easy to clean

3) Easy to find ammonia leakage

1) Compact structure

2) Good heat transfer effect

3) The temperature difference between the inlet and outlet of the cooling water is large, and the water consumption is large

1) Simple structure and convenient manufacturing

2) Small size and compact

3) Good heat transfer performance (water and refrigerant flow in reverse)

1) Simple manufacturing

2) Easy maintenance and cleaning

3) Unrestricted installation place

1) The heat transfer coefficient is lower than the horizontal shell and tube type

2) The cooling water inlet and outlet temperature difference is small, and the water consumption is large

1) Inconvenient cleaning

2) Ammonia leakage is not easy to find

1) Large metal consumption

2) Large flow resistance of cooling water

3) Difficult to clean scale

1) The flow rate of cooling water in the water tank is very low, so the heat transfer effect is poor

2) Large size

Medium and large ammonia refrigeration plant

Large, medium and small ammonia and Freon refrigeration devices can be used

Small Freon air-conditioning refrigeration unit 

Small freon refrigeration device

Air cooling water type (air cooling type)

No need for cooling water, very suitable for areas with difficult water supply, such as refrigerated trucks

1) Poor heat transfer effect

2) When the temperature is high, the condensation pressure will increase

Large, medium and small Freon refrigeration devices and air conditioners can be used

Water spray

1) Easy to manufacture

2) Easy to clean

3) Ammonia leakage is easy to find and maintenance is convenient

1) Large metal consumption

2) Large area

3) The heat transfer effect is worse than the shell and tube type

Medium and large ammonia refrigeration plant

Evaporative

1) Low water consumption, about 1/25-1/50 of the water consumption of shell and tube type

2) Compact structure, small size, small footprint

1) High cost

2) To increase pumps and fans, consume a certain amount of electricity

3) Trouble cleaning dirt and maintenance

Types of

Excellent point

Missing points

Use range

Evaporator for cooling liquid refrigerant

The open refrigerant evaporates in the tube

Riser

The vapor that the refrigerant evaporates in the neutral tube type quickly leaves the heat transfer surface, and the heat release coefficient on the refrigerant side is larger

Large metal consumption, processing man-hours, high cost, low flow rate on the water side, affecting heat transfer

Ammonia refrigeration system ice pool or cold water tank

Spiral tube

The heat transfer system is 12%-18% higher than that of the vertical tube type, the steel is 15% less than the vertical tube type, and the processing time is reduced by 40%

Difficulty in repairing when leaking

Ammonia refrigeration system ice pool or cold water tank

Snake coil type

Simple structure, convenient processing, safe work

Low flow rate of refrigerant in the box, poor heat transfer

Small freon device

Closed

Flooded shell and tube

The structure is simple, the area is small, the weight is light, and the consumption of metal materials is small. Because it is a closed system, the salt water is not in contact with the air, so it is less corrosive to the pipe.

The processing is more complicated, the welding quality requirements are high, the heat capacity is small, and the thermal stability is poor. When the salt water concentration is reduced, it is easy to freeze and cause the pipe tissue rupture accident

Ammonia refrigeration system, not suitable for marine use

Dry shell and tube

Compact structure, using aluminum core inner fin tube, good heat transfer effect, K value can reach 1163-1395W/㎡·K refrigerant is not easy to freeze, because the shell is equipped with baffle, the water speed can be as high as 1m/s , The oil return problem in Freon can be solved

There is a gap between the baffle, the shell and the tube, so that the refrigerant runs short and affects the heat transfer effect.

The assembly process of the baffle is more complicated, and it is difficult to clean the outside of the tube

As a water cooler in Freon refrigeration equipment

Evaporator for cooling air

Evaporation pipe

Vertical wall pipe

It is easy to process and make, the ammonia gas after evaporation is easy to draw out and the heat transfer effect is good

The large amount of liquid filling and the influence of liquid column pressure increase the refrigerant evaporation temperature at the bottom of the pipe

Suitable for wall pipes in cold storage of ammonia refrigeration system, not suitable for system

Snake coil

Convenient processing and production, small filling volume, about 50% of the volume of the coil, can be used as wall pipe or pre-pipe

Since each coil circuit is longer, about 120m, the refrigerant gas after the vapor is not easy to discharge, which reduces the heat transfer effect

Wall pipes and jacking pipes of ammonia and freon refrigeration equipment

U-shaped top pipe

The liquid supply circuit is short, the ammonia gas is easily drawn, and the heat transfer effect is good

If the position of the whole group is not level, it is easy to cause uneven liquid supply. When a liquid supply pipe is connected in parallel with several pipes, when the flow rate is small, uneven frosting will occur

Pipe jacking of ammonia refrigeration system, not suitable for Freon system

Shelf evaporator

Good heat transfer effect, uniform temperature

A large amount of steel is consumed, and the labor intensity of entering and leaving the warehouse when freezing food

Small ammonia and freon freezing device

Air cooler

Ceiling air cooler

Compact structure, small footprint, can be automated

If the defrosting water is not handled well, it will splash on indoor food or indoor floor. Poor air organization will cause uneven temperature difference in the room

Freezing room of ammonia refrigeration equipment, low temperature refrigerating room, high temperature storage room, refrigerating room of Freon refrigeration equipment

Floor-standing air cooler

Convenient installation, easy discharge of defrosting water, simple operation and maintenance, after installing the air duct, the indoor temperature is uniform

Large area

Freezing room and cold storage room of ammonia and freon refrigeration equipment

Wet air cooler

Simple structure, no frost, good heat transfer effect, stable temperature

The air flow resistance is large. If it is sprayed with salt water, the concentration will be reduced due to contact with the air. It is necessary to add salt frequently and is highly corrosive to the pipe.

Air conditioning system

Hybrid air cooler

Compact structure, no frost, good heat transfer effect

Salt water is highly corrosive to pipes

Air conditioning system

Failure phenomenon

cause of issue

Inspection Method

elimination method

No action when energized

Lead or coil open

Touch the solenoid valve by hand, check whether there is AC vibration, or stop and remove the lead wire, and use a multimeter to measure whether the passage

Connect the lead or rewind to replace the coil

There is a buzzing sound after power on

1. The moving iron core is jammed or damaged

2. Assembly error

3. There is more oil in the system, which hinders the action of the valve core

4. The voltage is lower than 85% of the rated value, the electromagnetic force is insufficient

5. The pressure difference between the inlet and outlet of the solenoid valve exceeds the valve opening capacity, and the iron core cannot be sucked up

1. Listen to whether there is a falling impact sound, if there is no impact sound, vibration and temperature rise, it means that the circuit is normal and the moving iron core is blocked.

2. Disassemble and check the position of each part

3. Remove and inspect

4. Measure voltage with a multimeter

5. Measure the pressure of the high pressure and low pressure section of the refrigeration system. See if the pressure difference meets the solenoid valve opening ability

1. Eliminate the jamming factor or replace the iron core

2. Disassemble the solenoid valve and reassemble it, especially the ten parts on the magnetic isolation conduit, which must be assembled in order to avoid affecting performance

3. Remove and clean

4. Adjust the power supply voltage

5. Eliminate factors such as small amount of cooling water, poor condenser heat dissipation, excessive non-condensable gas in the refrigeration system, etc., so that the high and low pressures are in a normal state

Lax closure

1. Damaged valve seat

2. The valve needle is roughened

3. The stolen goods make the valve not closed tightly

4. The pressure guiding orifice is blocked, the top pressure cannot be properly balanced, the resistance at the bottom of the piston increases, and the piston moves down and the piston cannot be pressed tightly on the valve seat.

5. The spring force is too small

To

6. The flow direction of the solenoid valve is opposite to the flow direction of the medium

The lax closure caused by any factor can be determined by the following methods:

1. Stop the compressor and observe the pressure in the low pressure section. If it is higher than the normal value, make the compressor work. After working for a period of time (it is better to reach the set stop temperature), stop the machine, and immediately close the liquid storage bottle infusion valve and observe the low pressure. Whether the segment rebound is too high, if it is not too high, it means that the solenoid valve is not closed tightly

2. The compressor works for a period of time. When the high and low pressure enters the normal state, stop immediately, touch the solenoid valve from time to time to see if it feels cold, and listen carefully for the sound of refrigerant shot at the solenoid valve. Lax

3. Disassemble the solenoid valve and filter for inspection

4. Visually inspect after disassembling the solenoid valve

5. Check the spring shape and free length

6. Check whether the arrow direction of the solenoid valve points to the expansion valve

1. Replace or repair the valve seat

2. Trim, polish or replace

3. Clean the valve filter, if the filter is damaged, it should be repaired, if the filter mesh is too thick, add another layer in the filter

4. Clean the solenoid valve and dredge the pressure guiding hole. If it is confirmed that it is correct, the pressure guiding hole can be enlarged by about 0.1mm. If the expansion does not work properly, the small hole should be riveted

5. To replace or rewind the spring, the original spring should be properly elongated in time

6. Put the solenoid valve into the system in one direction

Not shut down when power off

1. The moving iron core is stuck

2. Residual magnetism attracts moving iron core

Remove the solenoid valve, hold the moving iron core with a hand, and then push the iron core up to the dead point, let go to see if the residual magnetism can attract the moving iron core

1. Eliminate jamming factors

2. Try to demagnetize or replace with new materials

Medium leakage

1. The gasket is damaged

2. Uneven force on fastening screws

3. Weld leakage of magnetic isolation casing

1. Observe whether the gasket is damaged at the leakage of the medium

2. Tighten the screws with a screwdriver and test the tightness of the screws

3. Remove the magnetic isolation sleeve to observe whether there are oil traces on the outside

1. Tighten the screws or replace the washers

2. Loosen all screws and tighten again

3. Use brazing to repair leaks or replace new pipe sleeves

Failure phenomenon

cause of issue

Maintenance method

Float valve cannot open or close

1. There are welding slag, iron filings, rust mud and other garbage stuck in the system.

2. The floating ball itself has small holes, or the solder is corroded, causing the floating ball to leak and will not shut down.

3. The floating ball has been used for a long time, and the cylindrical valve body is seriously worn and can not be closed.

1. Install the filter and inspect and clean it regularly.

2. After the sand hole is welded, the blasting structure is changed to an electric welding structure.

3. Renew the cylindrical valve

Insufficient float

The cylindrical valve hole is not smooth enough, or the valve is oval or conical

Reaming holes with a reamer to make the finish and geometric shape accurate

The floating ball connecting rod is separated from the cylindrical valve, causing the floating ball to pass through, causing serious temperature stroke of the compressor

Adjust the split pin at the screw, the pin falls off during work

Reinstall the split pin after disassembly and inspection

The float ball falls, causing severe wet stroke

The manufacturing quality of the connecting rod is not good, the stress is concentrated, and the force screw is broken when it is too full

Re-manufacturing the connecting rod with tougher steel