Knowledge！Reference for maintenance content and methods of central air conditioning units

Posted on 2024-06-28

一. Three categories of central air conditioning maintenance

1. Inspection maintenance

Based on the equipment operation status and customer needs, various routine inspections are carried out in a planned manner;

On-site guidance of the owner's operating personnel, explaining the practical techniques involved in the operation and maintenance of the unit;

Provide various necessary value-added services;

Provide professional opinions and improvement plans for the problems existing in the operation of the main unit and auxiliary equipment;

2. Preventive maintenance

Contents provided by inspection maintenance;

Perform necessary preventive maintenance according to the manufacturer's recommendations;

Preventive maintenance includes: cleaning the copper tubes of the heat exchanger, analyzing and replacing the refrigeration oil, oil filter element, filter dryer, etc.;

3. Comprehensive maintenance

All routine inspections, value-added services and emergency fault handling services;

In the event of equipment failure, be responsible for all maintenance work and parts replacement;

Emergency maintenance, according to customer needs, provide customers with emergency maintenance services all day long, and the developed service network and high-quality service personnel team ensure rapid troubleshooting and ensure the shortest downtime.

二. Maintenance content of central air conditioning system

1. Air conditioning host part

Check whether the high and low pressure of the refrigerant in the air conditioning host refrigeration system are normal;

Check whether there is any leakage of the refrigerant in the air conditioning host refrigeration system; whether the refrigerant needs to be replenished;

Check whether the compressor operating current is normal;

Check whether the compressor operating sound is normal;

Check whether the compressor working voltage is normal;

Check whether the compressor oil level and color are normal;

Check whether the compressor oil pressure and oil temperature are normal;

Check whether the air conditioning host phase sequence protector is normal and whether there is a phase loss;

Check whether the wiring terminals of the air conditioning host are loose;

Check whether the water flow protection switch is working normally;

Check whether the computer board and the temperature sensor resistance are normal;

Check whether the air switch of the air conditioning host is normal; whether the AC contactor and thermal protector are in good condition.

2. Inspection of the air system

Check whether the air volume of the fan coil is normal

Check whether dust accumulates on the return air filter of the fan coil

Check whether the air outlet temperature is normal

3. Inspection of the water system

Check the water quality of the chilled water and whether the water needs to be replaced;

Check the impurities on the filter in the chilled water system and clean the filter;

Check whether there is air in the water system and whether exhaust is needed;

Check whether the return and outlet water temperatures are normal;

Check whether the sound of the water pump and the current are running properly;

Check whether the valve is flexible to open, whether there are rust spots, whether there are leaks, etc.;

Check whether the insulation system is cracked, damaged, leaking, etc.;

三. Maintenance content of central air conditioner

1. Maintenance during normal operation

Check the oil pressure and oil volume of compressor refrigeration oil;

System leak detection (refrigerant), find leaks and deal with them in time;

Check for abnormal sounds, vibrations and high temperatures;

Check the temperature and pressure of the condenser and cooler;

Check whether various valves are normal;

Check the temperature and pressure of the water inlet and outlet of the chiller;

Check the wiring terminals on the main circuit and compact them;

Check the electrical control part;

Check the unit lubrication system;

Check the working status of each instrument and controller;

Keep the equipment in a clean state.

2. Maintenance after annual shutdown

Check and clean the dry filter. The desiccant should be dried or replaced after absorbing moisture;

Check and set the safety protection device of the refrigeration equipment;

Check the oil pressure and oil volume of the compressor refrigeration oil, and replace and replenish the refrigeration oil if necessary;

Check the insulation of the compressor motor;

Check and tighten the wire contacts on the circuit;

Check the electrical control part.

3. Terminal maintenance

Inspection of air handling units and fan coils;

Maintenance and refueling of air handling units and fan coils;

Inspection and adjustment of belts, cleaning of surface coolers, and cleaning of filters;

Pipe cleaning and decontamination;

Cleaning and dust removal of air handling units.

4. Water system maintenance work content

Chiller water pump inspection and refueling;

Insulation inspection, refueling, inspection and replacement of sealing components for motors and electrical appliances;

Inspection and replacement and repair of insulation conditions of valves, filters, one-way valves, pressure gauges, and thermometers at key parts of the water system.
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四. Maintenance methods of central air conditioners

The maintenance and repair contracting methods of central air conditioners are divided into three types: large package, medium package and small package.

Large package: A large package is a contract signed every three or five years. The contract content includes the replacement costs of all parts of the air conditioning system, the labor costs of maintenance and daily operation management, the costs of daily maintenance and inspection, the costs of routine comprehensive inspections twice a month, [Source of this article: Refrigeration Encyclopedia WeChat Account], system cleaning and oil change costs, etc. All problems caused by the unit and system are within the scope of warranty.

Features: high contracting costs, high risks, high profits, many people, and a certain amount of spare parts inventory. Therefore, in order to balance the failure rate and reduce risks, the contract is generally more than three years.

Medium package: The medium package contract is more than two years. Compared with the large package, it only reduces the management expenses of daily operation personnel (that is, all maintenance, materials and labor costs are included, but not operation and management costs)

Small package: Small package refers to the labor cost of maintenance only, not any material cost of maintenance. When the unit fails and needs to be repaired or routine maintenance, the material cost incurred shall be signed by Party A and Party A again, or Party A provides the materials and we repair them free of charge.

Features: low contracting cost, low risk, low profit, small number of personnel, no spare parts, and the contract is generally signed for one year. The air conditioner user and the maintenance party reach an agreement on the daily operation, maintenance, emergency repair, seasonal maintenance, etc. of the air conditioner, and deliver all or part of the above work.