Good oil pressure is 20-60 psid, this is the differential between crankcase and oil pump discharge.

When selecting a compressor the capacity is listed under specific conditions (Example: ARI conditions for air conditioning compressors is at 130°F (54.4°C) condensing and 45°F (7.2°C) evaporator). A compressor capacity will change as the load changes. To accurately check compressor capacity one should note the conditions you are operating at and plot these on a capacity curve designed for the specific compressor and refrigerant you are using. In short, the capacity that the compressor is drawing is specific to the conditions. To obtain capacity data please visit the Online Product Information (OPI) database.

Copeland^® protectors are inherent, meaning they sense both temperature and amperage. If a protector trips, the system should be investigated for the increased temperature or amperage problem. Some causes could be charge shortage, high head pressures, increased friction of moving parts, reduced voltage, unbalanced voltages, shorted windings, etc.

First, we must recognize that there is no such thing as a nuisance oil control trip. The tripped control is warning you of an existing problem. The system should not be reset until you have looked in the sight glass and recorded the level. If the oil is below the glass, the system should be checked for leaks or oil logging. Investigate for the oil return problem. This could be corrected by longer or more defrost cycles, reducing short cycling, preventing low refrigerant charge, eliminating piping problems, etc. If it is determined that oil should be added it must be removed once the problem is remedied.

If the oil is above the glass, the system should be checked for the possibility of refrigerant diluting the oil. Liquid refrigerant floodback could be identified by absence of superheat at the compressor. It would be advisable to separate the refrigerant from the oil by heating the oil with a crankcase heater a few hours before starting or by jogging the compressor (quick start/stop of the compressor several times) until the foaming is controlled. Remember the suction service valve should not be closed while jogging the compressor. If the valve is closed the refrigerant and oil could manage a more violent explosion (flooded start) as there is less space for the initial start-up pressure to be pulled from.

If the oil level is in the sight glass, the oil may be checked if it is too hot. Identify this by checking the temperature six inches out on the discharge line. The maximum is 225°F (107.2°C) at this distance. Any higher temperatures could mean that the cylinder temperature is above 300°F (148.9°C) and it could cause oil control trips. If the oil is foaming excessively it may have refrigerant dilution and may be identified as a floodback problem. On refrigerant cooled semi-hermetic compressors, the problem could be an over-pressurized crankcase. The root of this problem is overheat that causes excessive crankcase pressures due to piston blow by at low loads. The problem may be found by attaching a gauge manifold set to the crankcase and the suction. With the compressor operating, start slowly front seating the suction service valve. Observation of the gages should show both falling at an equal amount until the valve is fully front seated. The point at which the crankcase gauge stops falling is proof that the crankcase blow by pressure exceeds the venting.

Overheating problems occur when oil in a compressor is heated to the point where it loses its ability to lubricate. If the heat is high enough, the oil breaks down chemically. Major reasons for overheating due to discharge temperatures are:

• Low suction pressures
• High condensing pressures
• High compression ratios

Low suction pressure is normally the result of incorrect pressure switch settings, pressure drop in suction line, light load operating conditions or restricted evaporator coils. High condensing pressures can be caused by inadequate airflow through the condenser, undersized discharge line/condenser, and overcharge of refrigerant or noncondensables in the system. High-pressure ratios are a combination of low suction pressures and high condensing pressures. If the compressor is operated within the manufacturer guidelines, this condition will not cause a problem. Emerson recommends monitoring discharge line temperatures to determine if the compressor is in a danger zone of overheating. Generally, discharge line temperature of 225ºF (107.2°C) and below will insure the compressor of a long life.

Possible causes include:

• Compressor oversized for load
• The "cycle on" and "cycle off" range of low pressure control is set too close
• Undersized evaporator/suction line piping
• A leak in liquid line solenoid valve
• Oil float feeding erratically
• The compressor shows a high to low internal leak

In many cases, replacing the compressor will not resolve the sound issue and it is recommended that different possible noise sources be explored before a compressor exchange is considered. The noise radiated by A/C systems can be generated by:

• Compressor noise as an airborne sound
• Structural vibration of system's components such as refrigerant pipes, panels etc.
• Outdoor/indoor fan Because of the interaction between these sources of noise, it is sometimes difficult to pinpoint the origins of noise using the ear only. In general, the compressor is not the principal noise generator if the noise is heard only indoors or if the noise is still present when only the fan is running. For more information on this topic see Scroll Sound Enclosures.

The only universal start assist device approved for Copeland single-phase compressors is a PTCR (Positive Temperature Coefficient Resistor) device with a resistance as low as 12.5 ohms or higher. These devices are made by various manufacturers and are applied parallel to the run capacitor. They are approved only as low volt start-assist with piston compressors in systems where the refrigerant pressure equalizes or scroll bearing units. All other applications must use the specified Emerson start capacitor and relay combination. For more information on this topic see Scroll Start Components and Compressor Start Components.

The simplest device to reduce light dimming caused by voltage drop while the compressor is starting is to add a start capacitor and relay. The capacitor and relay will reduce the amount of time the compressor is in locked rotor and thus reduces the amount of time the bulbs dim to a tolerable flicker.

For more information on this topic see Scroll Start Components.

The best way to determine if a compressor is pumping properly is with a set of gages, an amp meter and the compressor specification sheet. Measure the operating discharge and suction pressure as well as the amperage. Using the compressor curve sheet, found on the Online Product Information (OPI) database, compare the amperage reading at the measured pressures. Because of voltage variations and measurement inaccuracies the measured amperage should compare to the actual curve sheet values within +/- 15%. Never check compressor operation by closing the suction valve to see how low the suction will go. This might actually cause damage to the compressor because of heat build up.

Since Emerson Climate Technologies is a technology provider; we lack the field experience to adequately answer piping questions such as this. We would recommend following the system Original Equipment Manufacturer's (OEM) guidelines, if available. Where such information is not available, we would recommend using standard ASHRAE piping guidelines or the tables found in Emerson's refrigeration manuals AE-101 through 105. These are available through an Emerson wholesaler for a nominal fee. For more information on a related topic see AE Bulletin 22-1182. This bulletin can be located using the Online Product Information (OPI) section of our website.

The amount of oil in fluid ounces is on the nameplate in the box marked oil. A complete recharge is four fluid ounces less than this amount since some of the oil remains in the compressor after draining. For more information on oil used in Copeland^® compressors see AE Bulletin 17-1248 or log in to the Online Product Information (OPI) page.

Emerson Climate Technologies organizes technical seminars regularly across various countries in the Asia Pacific region. Please contact us for the calendar of events.

The new refrigerants are considered “higher efficient” and they are trying to sell refrigerants under the requirement of fewer component change outs. For example, an expansion valve works to full capacity if it has full liquid (subcooled liquid) to its inlet. If the expansion valve is considered oversized for the new refrigerant then the valve capacity will decrease if the refrigerant starts to boil off before the inlet of the valve. The vapor molecules take up more space than the liquid molecules, therefore, less refrigerant passes through the valve with vapor. Emerson recommends valves to be sized accordingly and to charge the system as basic rules apply: expansion valves are charged by clearing the sight glass in the liquid line at high load (subcooling) and the cap tubes are charged by evaporator superheat at low load conditions. If only a percentage of charge is used the compressor could overheat during an extended high load condition.

Emerson does not approve the use of Alkyl Benzene oil with R-404A. R-404A is a HFC and Polyol Ester is the only approved oil. The Alkyl Benzene will not be miscible with the HFC. The HCFC refrigerants have a small amount of chlorine that is miscible with the AB oil. Tests have proven that oil return problems result when AB is used with R-404A.

The refrigerant charge is critical in capillary tube systems since normally there is no receiver to store excess refrigerant. Too much refrigerant will cause high discharge pressures and motor overloading, and possible liquid floodback to the compressor during the off cycle; too little will allow vapor to enter the capillary tube causing a loss in system capacity.

A drier is designed to be a temporary device to clean a system after a burnout. The suction line acts like a chimney during the burn and the soot carries into the accumulator. The soot will need to be caught before entering a newly installed compressor. For this reason we suggest that the drier be installed between the compressor and the accumulator. It should be removed within 48 hours and replaced until the system is cleaned and acid free. At this time it may be removed or a filter left in place. The filter may be installed up stream of the accumulator to keep the accumulator from being contaminated.

Only Emerson authorized start components should be used. We have tested and approved the heavy-duty start components. Contact us for more information.

Superheat at the evaporator should be checked as close to the end of the coil as possible (preferably near the expansion valve thermal bulb). Take the pressure at this location with a pressure tap or to the shrader valve. Convert this to saturation temperature and compare it to the actual temperature obtained near the thermal bulb.

Superheat at the compressor should be checked at the compressor only. Take the suction pressure at the service valve and convert it to saturation temperature. Compare this to the actual temperature obtained approximately six inches out on the suction line.

Subcooling should be checked as close to the inlet of the evaporator metering device as possible. Take the pressure of the liquid line near the metering device inlet and convert this to saturation temperature. Compare it to the actual temperature obtained near the same point the pressure was obtained.

Net oil should compare the actual forces that work on the oil pump. This includes oil pump outlet pressure and crankcase pressure (not suction pressure). The suction pressure on a semi-hermetic refrigerant cooled compressor may be a couple of pounds pressure difference from the actual crankcase pressure. This especially holds true if the compressor is a two-stage application that has intermediate pressure working on the crankcase. Place a gauge manifold on the oil pump discharge and one on the compressor crankcase, the difference is net oil pressure.

Yes. Refer to the publication, No. 93-11 from Emerson Climate Technologies.

Yes. Refer to the publication No. 93-11 from Emerson Climate Technologies.

Yes. Refer to publication No. 93-11 from Emerson Climate Technologies,.

No. Additives are not permitted. Refer to Application Engineering Bulletin No. 17-1282. This bulletin can be located using the Online Product Information (OPI) section of our website.

Exposure to ambient air will cause moisture to be absorbed in the POE oil. Refer to various HFC refrigerant retrofit guidelines published by Emerson Climate Technologies.

No. It may result in a motor protector trip due to high amps.

The viscosity of oils used in Copeland^® compressors is selected by the design of the compressor and varies from 22 to 32 cst (centistokes). Refer to the Emerson Climate Technologies publication No. 93-11 for further details.

Approved refrigerants can be found in the Emerson Climate Technologies publication No. 93-11.

Refer to the refrigerant changeover guidelines from Emerson Climate Technologies.

Emerson Climate Technologies recommends topping with approved oils as listed in publication No. 93-11. Use of non-approved oils may result in oil management and lubrication issues that could lead to system inefficiencies and compressor failure.

No. Oils vary in viscosity, formulation, etc. and are designed for different applications in different compressors.

Emerson Climate Technologies recommends using oils approved as listed in publication No. 93-11. Use of non-approved oils may result in oil management and lubrication issues that could lead to system inefficiencies and compressor failure.

Exposure to ambient air will cause moisture to be absorbed in the oil. Refer to the various HFC refrigerant retrofit guidelines published by Emerson Climate Technologies.

Investigation of failed compressors generally requires oil analysis.