Car auto air conditioning adding oil to system and how much

You can test your system to see how much oil in present see our post here 

You can find the specs for your car and it will tell you the amount of refrigerant needed and the amount of oil needed.

If you recover the refrigerant from the system and change a component within the system then you need to add oil here is a rough guide to amounts of oil needed.

Major system leak ( empty gas ) 1.5 fluid oz

Minor system leak ( pressure switch shut off compressor ) 0.5 oz

Accumulator  1.5 oz

Condenser  1 oz

Evaporator   1 oz

Receiver drier    0.5 oz 

Hoses  0.5 oz 

compressor  measure the amount of oil internal to compressor and replace this into system in new compressor ( typical 2 oz )

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Car auto Air conditioning electrical testing

First I go into the car and ensure the Air con is on and the blower is on at least halfway, I now check the compressor to ensure the clutch has engaged and that the pulley is turning the compressor. If the compressor is on and working you can assume the electrics are pretty much good.

If the compressor does not on then you need to fault find.

Firstly id check the pressure in the system as without pressure the pressure switch will not allow compressor clutch engagement.

If pressure is good id now look for the relay that controls the compressor clutch operation you can test the control side of the relay for power and ground if you have both you can be assured that all the controls in the car are fine  if not you need to look at the climate control panel internally, these can be replaced as one unit.

Now you can test the load side of the relay which is the compressors clutch, you can load the circuit with 12v to see if the clutch operates if it does its all fine if not you need to replace the compressor clutch solenoid. see our post of this here 

The 3 wire pressure switch ( see our post on these here )

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How cars auto air conditioning system works and all components

 

Starting for the compressor the refrigerant is pumped from compressor to the condenser as its passed through the compressor its now ad high pressure vapour ( compressor only pumps vapour liquid would damaged it ), the condenser then cools the heated vapour and as it leaves it will be a high pressure liquid.

 It now passes the drier which removes any of the remaining vapour and ensure no moisture is present.

Next it will pass through the expansion valve and into the evaporator its this expansion from high pressure liquid to low pressure liquid vapour that cause the freezing effect to cool the evaporator and eventually the cabin air.  

The low pressure vapour then returns to compressor to begin cycle again.

Compressor - or air con pump is basically the engine of the A/C system it is belt driven from the cars engine. It pressurises and pumps the refrigerant around the A/C system. Its a vital part of the system and if it fails the A/C will not function. Failures can include leakages from connections, failure due to lack of lubrication, incorrect compressor clutch engagement.

Condenser/fan - This unit receives the high pressure super heated vapour from the compressor, it passes through the condenser piping and gives off heat to the atmosphere the via radiation fins. A fan is used to force air over the fins to remove this heat. A a result of the higher pressures and cooling the vapour with turn into liquid. 

Drier / receiver - This unit absorbs any moisture that may be within the system , they will also trap any debris that might be in the system , it is a storage unit for oil/refrigerant when not in high demand and it prevents any left over vapour and allows only liquid reach the thermal expansion valve.

Expansion valve -  This basically restricts the flow of refrigerant and converts the high pressure liquid into low pressure vapour which cause the temperature of the vapour to drop and cause the evaporator to drop in temperature.

Evaporator - this is used to pass on the cold from the expanded refrigerant via radiation to the air that is being fed into the cars cabin. 

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