Tag: ac compressor protection

Different types of oil

how much oil does my car ac system need ?

how much oil does my car ac system need ?

Proper lubrication is a must for ac compressor long life. When the a/c compressor is operated ,oil gradually leaves the compressor, and the oil is circulated through the entire ac system together  with the refrigerant. After the air conditioning system is operated for the first time an oil balanced condition is reached in which a certain amount of oil is retained in the compressor and a certain amount is re-circulated through the ac system components with different amounts of oil depositing in them . If a component of the system is replaced after the system has been operated, we need to compensate for this by adding oil to the new replacement ac part.

HOW AN OVERCHARGE/UNDERCHARGE A/C OIL CONDITION AFFECT THE A/C SYSTEM?

Too much oil in the a/c system could result in extremely high head pressures which will cause poor air conditioning performance and premature wear and failure of the hvac compressor. If there is a surplus of oil in the system, too much oil circulates with the refrigerant ,causing the cooling capacity of the system to be reduced and the compressor head pressure to increase. Too little oil results in poor lubrication of the compressor and an increase in the heat of compression which shorten the life of the ac compressor.

OIL BALANCING AN AC SYSTEM

When there has been excessive leakage of refrigerant, or it is necessary to  replace a component of the refrigeration system oil balancing is necessary to assure that the total oil charge in the system is the correct one after the leak has been repaired or the new ac part is installed in the car.

HOW TO OIL BALANCE MY CAR AC SYSTEM

The recommended procedure step by step

  1. Measure the oil recovered from the system while recovering the refrigerant prior to part replacement
  2. Drain and measure the oil left in the old part
  3. Drain the new part(if factory oil-prefilled)
  4. Refill the new part with the same amount of oil removed from the old part and the amount of oil recovered from the system

WHAT TYPE OF OIL ACCORDING TO TYPE OF REFRIGERANT R-12 R-1234YF AND R-134a

The refrigerant oil required by the automotive ac system depends on a number of factors ,but it is primarily dictated by the type of refrigerant used in the system.R-12 car systems used a mineral oil. Mineral oil mixes well with R-12  without breaking down and losing its lubrication characteristics. Mineral oil however cannot be used  to lubricate ac systems with R-134a refrigerant.R-134 systems require a different synthetic oil,polyalkylene glycol (PAG).There are different blends of PAG and POE oil; always use the recommended by the vehicle manufacturer or the replacement part manufacturer.

The lubricant oil used in automotive air-conditioning systems is a non-foaming, sulfur free grade specially formulated for use in cars a/c systems. New refrigerants like R-1234yf might use PAG 46 and are backwards compatible for use with R-134a systems, but the R-134a old PAG 46 oils are not forward compatible with R-1234yf systems.

OIL RECHARGE AMOUNTS

REFRIGERANT OIL Recommended PAG oil: DENSO ND-OIL 8  
Add the recommend refrigerant  oil in the amount listed if you replace any of the following parts:
A/C condenser(including receive Dryer. 25 mL (5/6 fl oz)
Evaporator 40 mL (1 1/3 fl oz)
Line or hose 10 mL (1/3 fl oz)
Receiver/dryer 10 mL (1/3 fl oz)
Leakage repair 25 mL (5/6 fl oz)
A/C compressor For A/C compressor replacement, subtract the volume of oil drained from the removed A/C compressor from 82 mL (2 3/4 fl oz), and drain the calculated volume of oil from the new A/C compressor: 82 mL (2 3/4 fl oz) - Volume of removed A/C compressor = Volume to drain from new A/C compressor.
NOTE: Even if no oil is drained from the removed A/C compressor, do not drain more than 50 mL (1 2/3 fl oz) from the new A/C compressor.

NEED ASSISTANCE

automotive refrigerant control devices.

What is compressor protection ?

AC compressor circuit protection.

Some compressor clutch circuits contain a thermal limiter switch that senses compressor surface temperature. Some A/C compressor clutch circuits also contain a low-pressure cutoff switch. 

A/C safety switches .

A/C systems have load-sensitive electrical switches; such as the low-pressure switch, high-pressure switch, pressure cycling, and power steering. Not all the switches, however, are used in all vehicles. The pressure switches are used to prevent compressor or component damage in the event of extremely high or low-system pressures.

Air conditioning controllers.

A/C Protection Devices.

Thermal switches are used on both the low and high side of AC systems. A Thermal switch may be connected in series with the compressor clutch.

A/C compressor cycling control .

A thermostatic switch de-energizes the clutch and stops the compressor to keep the evaporator from freezing up. When the temperature of the evaporator approaches the freezing point (or the low setting of the switch), the thermostatic switch opens the circuit and disengages the compressor clutch. The compressor remains inoperative until the evaporator temperature rises to the preset temperature, at which time the switch closes and compressor operation resumes.

A/C Compressor temperature control.

A thermal limit switch may be mounted on or near the compressor and is used to stop compressor operation before the temperature of the compressor reaches a point of damage.