How to Figure the Compressor Surge on an Air Conditioner

Air Conditioner Systems

• An air conditioner compressor releases heat into the outside air by compressing heat gases out of the refrigerant liquids that flow through the system. Refrigeration systems use coils to join a condenser unit with an air handler unit. The compressor works inside the condenser unit. Refrigerant liquids absorb indoor heat from the air handler unit and send it to the condenser unit through the cooling coil. The condenser converts this heat into gases and releases them into the outdoors before sending the refrigerant back to the air handler. From this point, the air handler uses a fan to blow air across the evaporator coil and deliver cool air into the home.

Pressure Levels

• An air conditioner system consists of a low pressure side and a high pressure side. With most system setups, the air handler device sits indoors while the condenser sits outdoors. As refrigerant materials move through the system, different amounts of pressure are applied at different points. The low pressure side of the system appears where refrigerant materials move from the air handler to the condenser-compressor unit. Pressure levels increase or surge as the compressor squeezes heat gases out of refrigerant liquids. So, when refrigerant materials exit the condenser-compressor unit, pressure levels increase. As a result, the high pressure side of an air conditioning system appears where refrigerant materials move from the condenser unit to the air handler.

Temperature Levels

• Temperature levels within an air conditioning system correspond with pressure levels in terms of high side versus low side. The high, or surge, side of the system also carries higher temperatures than the low side. This means refrigerant materials carry a higher temperature on the condenser-compressor side of the system. As refrigerants move towards the air handler device, the liquids carry a lower temperature as a result of the compressor’s cooling effect.

  Temperature differences between the outside air and the compressor unit also allow the compressor to discharge heat gases into the outside air. In other words, temperatures inside the compressor must exceed outside air temperatures for heat gases to flow into the outside air.

Surge Levels

• Surge level requirements for a condenser-compressor unit depend on an air conditioner’s size, design, compressor motor size and the type of refrigerant materials used. Optimal pressure settings should appear on the label attached to the air conditioner unit; however, outside air temperatures will ultimately determine what pressure levels work best.

  Optimal pressure levels can be figured according to standard measurements that use outside air temperatures and refrigerant type as guidelines. For systems that require an R-22 refrigerant, air temperatures inside the compressor must exceed outdoor air temperatures by 35 degrees. On the low side of the condenser-compressor unit, compressor temperatures should run at 40 degrees below outside air temperatures. As far as air pressure levels go, the unit’s service manual should list corresponding air pressures for different compressor temperature levels.