Carrier Infinity 24VNA6 Series Service Manual

Also see for Infinity 24VNA6: Installation instructions Owner's manual

24VNA6 / 25VNA4: Service ManualManufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.35REFRIGERATION SYSTEMRefrigerantIn an air conditioning and heat pump system, refrigerant transfers heatfrom one place to another. The condenser is the outdoor coil in thecooling mode and the evaporator is the indoor coil.In a heat pump, the condenser is the indoor coil in the heating mode andthe evaporator is the outdoor coil.In the typical air conditioning mode, compressed hot gas leaves thecompressor and enters the condensing coil. As gas passes through thecondenser coil, it rejects heat and condenses into liquid. The liquidleaves condensing unit through liquid line and enters metering device atevaporator coil. As it passes through metering device, it becomes agas-liquid mixture. As it passes through indoor coil, it absorbs heat andthe refrigerant moves to the compressor and is again compressed to hotgas, and cycle repeats.Compressor OilServicing Systems on Roofs With SyntheticMaterialsPolyvinyl ether (PVE) compressor lubricants are known to cause longterm damage to some synthetic roofing materials. Exposure, even ifimmediately cleaned up, may cause embrittlement (leading to cracking)to occur in one year or more. When performing any service which mayrisk exposure of compressor oil to the roof, take appropriate precautionsto protect roofing. Procedures which risk oil leakage include but are notlimited to compressor replacement, repairing refrigerants leaks,replacing refrigerant components such as filter drier, pressure switch,metering device, coil, accumulator, or reversing valve.Synthetic Roof Precautionary Procedure1. Cover extended roof working area with an impermeablepolyethylene (plastic) drop cloth or tarp. Cover an approximate 10x 10 ft area.2. Cover area in front of the unit service panel with a terry cloth shoptowel to absorb lubricant spills and prevent run-offs, and protectdrop cloth from tears caused by tools or components.3. Place terry cloth shop towel inside unit immediately undercomponent(s) to be serviced and prevent lubricant run-offs throughthe louvered openings in the base pan.4. Perform required service.5. Remove and dispose of any oil contaminated material per localcodes.BrazingThis section on brazing is not intended to teach a technician how tobraze. There are books and classes which teach and refine brazingtechniques. The basic points below are listed only as a reminder.Definition: The joining and sealing of metals using a nonferrous metalhaving a melting point over 800°F/426.6°C.Flux: A cleaning solution applied to tubing or wire before it is brazed.Flux improves the strength of the brazed connection.When brazing is required in the refrigeration system, certain basicsshould be remembered. The following are a few of the basic rules.1. Clean joints make the best joints. To clean:– Remove all oxidation from surfaces to a shiny finish beforebrazing.– Remove all flux residue with brush and water while material is stillhot.2. Silver brazing alloy is used on copper-to-brass, copper-to-steel, orcopper-to-copper. Flux is required when using silver brazing alloy.Do not use low temperature solder.3. Fluxes should be used carefully. Avoid excessive application and donot allow fluxes to enter into the system.4. Brazing temperature of copper is proper when it is heated to aminimum temperature of 800°F and it is a dull red color inappearance.Service Valves and PumpdownService valves provide a means for holding original factory charge inoutdoor unit prior to hookup to indoor coil. They also contain gaugeports for measuring system pressures and provide shutoff conveniencefor certain types of repairs.The service valve is a front-seating valve, which has a service port thatcontains a Schrader fitting. The service port is always pressurized afterthe valve is moved off the front-seat position.The service valves in the outdoor unit come from the factoryfront-seated. This means that the refrigerant charge is isolated from theline-set connection ports. The interconnecting tubing (line set) can bebrazed to the service valves using industry accepted methods andmaterials. Consult local codes.Before brazing the line set to the valve, the belled ends of the sweatconnections on the service valves must be cleaned so that no brassplating remains on either the inside or outside of the bell joint. Toprevent damage to the valve and/or cap “O” ring, use a wet cloth orother acceptable heat-sinking material on the valve before brazing. Toprevent damage to the unit, use a metal barrier between brazing area andunit.After the brazing operation and the refrigerant tubing and evaporator coilhave been evacuated, the valve stem can be turned counterclockwiseuntil back-seats, which releases refrigerant into tubing and evaporatorcoil. The system can now be operated.The service valve-stem cap is tightened to 20 ± 2 ft/lb torque and theservice-port caps to 9 ± 2 ft/lb torque. The seating surface of the valvestem has a knife-set edge against which the caps are tightened to attain ametal-to-metal seal.WARNING!UNIT OPERATION AND SAFETY HAZARDFailure to follow this warning could result in personal injury orequipment damage.Puronr refrigerant which has higher pressures than R-22 and otherrefrigerants. No other refrigerant may be used in this system. Gauge set,hoses, and recovery system must be designed to handle Puronr. If youare unsure consult the equipment manufacturer.CAUTION!UNIT DAMAGE HAZARDFailure to follow this caution may result in equipment damage orimproper operation.The compressor in a Puron system uses a polyvinyl ether (PVE) oil.This oil is extremely hygroscopic, meaning it absorbs water readily.PVE oils can absorb 15 times as much water as other oils designed forHCFC and CFC refrigerants. Take all necessary precautions to avoidexposure of the oil to the atmosphere.WARNING!PERSONAL INJURY AND UNIT DAMAGE HAZARDFailure to follow this warning could result in personal injury orequipment damage.Never attempt to make repairs to existing service valves. Unit operatesunder high pressure. Damaged seats and o-rings should not be replaced.Replacement of entire service valve is required. Service valve must bereplaced by properly trained service technician.