Friedrich R-410A service manual 410A Sealed Refrigeration System Repairs, Equipment Required

R-410A SEALED REFRIGERATION SYSTEM REPAIRS

IMPORTANT

SEALED SYSTEM REPAIRS TO COOL-ONLY MODELS REQUIRE THE INSTALLATION OF A LIQUID LINE DRIER.

EQUIPMENT REQUIRED:

1.Voltmeter

2.Ammeter

3.Ohmmeter

4.E.P.A. Approved Refrigerant Recovery System

5.Vacuum Pump (capable of 200 microns or less vacuum.)

6.Acetylene Welder

7.Electronic Halogen Leak Detector capable of detecting HFC (Hydrofluorocarbon) refrigerants.

8.Accurate refrigerant charge measuring device such as:

a.Balance Scales - 1/2 oz. accuracy

b.Charging Board - 1/2 oz. accuracy

9.High Pressure Gauge - (0 to 750 lbs.)

10.Low Pressure Gauge - (-30 to 200 lbs.)

11.Vacuum Gauge - (0 - 1000 microns)

12.Facilities for flowing nitrogen through refrigeration tubing during all brazing processes.

EQUIPMENT MUST BE CAPABLE OF:

1.Recovering refrigerant to EPA required levels.

2.Evacuation from both the high side and low side of the system simultaneously.

3.Introducing refrigerant charge into high side of the system.

4.Accurately weighing the refrigerant charge introduced into the system.

WARNING

RISK OF ELECTRIC SHOCK

Unplug and/or disconnect all electrical power to the unit before performing inspections, maintenances or service.

Failure to do so could result in electric shock, serious injury or death.

WARNING

HIGH PRESSURE HAZARD

Sealed Refrigeration System contains refrigerant and oil under high pressure.

Proper safety procedures must be followed, and proper protective clothing must be worn when working with refrigerants.

Failure to follow these procedures could result in serious injury or death.

Proper refrigerant charge is essential to proper unit operation. Operating a unit with an improper refrigerant charge will result in reduced performance (capacity) and/or efficiency. Accordingly, the use of proper charging methods during servicing will insure that the unit is functioning as designed and that its compressor will not be damaged.

Too much refrigerant (overcharge) in the system is just as bad (if not worse) than not enough refrigerant (undercharge). They both can be the source of certain compressor failures if they remain uncorrected for any period of time. Quite often, other problems (such as low air flow across evaporator, etc.) are misdiagnosed as refrigerant charge problems. The refrigerant circuit diagnosis chart will assist you in properly diagnosing these systems.

An overcharged unit will at times return liquid refrigerant (slugging) back to the suction side of the compressor eventually causing a mechanical failure within the compressor. This mechanical failure can manifest itself as valve failure, bearing failure, and/or other mechanical failure. The specific type of failure will be influenced by the amount of liquid being returned, and the length of time the slugging continues.

Refrigerant Charging

NOTE: Because the RAC system is a sealed system, service process tubes will have to be installed. First install a line tap and remove refrigerant from system. Make necessary sealed system repairs and vacuum system. Crimp process tube line and solder end shut. Do not leave a service valve in the sealed system.

Not enough refrigerant (undercharge) on the other hand, will cause the temperature of the suction gas to increase to the point where it does not provide sufficient cooling for the compressor motor. When this occurs, the motor winding temperature will increase causing the motor to overheat and possibly cycle open the compressor overload protector. Continued overheating of the motor windings and/or cycling of the overload will eventually lead to compressor motor or overload failure.

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