Vehicle A/C Gas/Oil Charge.

[james 100]

Can anyone help please?

My vehicle has a charge weight and amount/spec of oil to be added, my questions are:-

1, Does the amount of oil shown on the plate have to be added each time the unit is re charged?

2,As the unit has not lost its charge (new to me vehicle, i want to recover and weigh in correct charge before it warms up and we get busy) where does the oil sit, do vehicle compressors have sumps?

3,If i recover the refrigerant and inject the oil, will putting it on to a deep vac not pull some of the oil back out again?

As you can tell i do not work on vehicle a/c as a rule but i would like to make sure my vehicle is done properly. ;)

Any help, tips greatly appreiciated.:D

[Brian_UK]

Can anyone help please?

My vehicle has a charge weight and amount/spec of oil to be added, my questions are:-

1, Does the amount of oil shown on the plate have to be added each time the unit is re charged?No the oil should stay inside the system, even a leak will not lose the oil charge - unless it is a major leak of course.


2,As the unit has not lost its charge (new to me vehicle, i want to recover and weigh in correct charge before it warms up and we get busy) where does the oil sit, do vehicle compressors have sumps?Yes they have a sump, it's called the main casing. ;)

Most of the oil should be in the compressor but some will be around the system.


3,If i recover the refrigerant and inject the oil, will putting it on to a deep vac not pull some of the oil back out again?A vacuum pump has never evaporated oil yet.


As you can tell i do not work on vehicle a/c as a rule:D No, really, I would never have guessed :D


but i would like to make sure my vehicle is done properly.I'm sure it will be after you have finished playing with it.


Any help, tips greatly appreciated.:DIf you ever open the system the atmosphere then you will need to replace the filter/drier and as that can be a pain to do sometimes keep saying to yourself "I must keep it dry, I must keep it dry."

When recharging keep the engine revs at around 2000 if you can. Carry spare fuses for the condenser/radiator fan(s).

[james 100]

No the oil should stay inside the system, even a leak will not lose the oil charge - unless it is a major leak of course.

Yes they have a sump, it's called the main casing. ;)

Most of the oil should be in the compressor but some will be around the system.

A vacuum pump has never evaporated oil yet.

:D No, really, I would never have guessed :D



I'm sure it will be after you have finished playing with it.

If you ever open the system the atmosphere then you will need to replace the filter/drier and as that can be a pain to do sometimes keep saying to yourself "I must keep it dry, I must keep it dry."

When recharging keep the engine revs at around 2000 if you can. Carry spare fuses for the condenser/radiator fan(s).


So if the system has not lost complete charge i can assume there is no need to worry about the oil charge then? :confused:

And in which case i have no need to replace the dryer (approx £48) as all i will be doing is recovering, pressure testing and re charging, no need to open to to atmos?

[Brian_UK]

That's right James.

Also, when weighing in the charge allow for the refrigerant in your charging lines. If possible fill your lines up to the charging valve, reset the scales and then connect on to the system, or open the valve if already connected.

[james 100]

That's right James.

Also, when weighing in the charge allow for the refrigerant in your charging lines. If possible fill your lines up to the charging valve, reset the scales and then connect on to the system, or open the valve if already connected.

Thanks Brian, thats what i thought but its nice to be sure. :)

[chemi-cool]

And to preform the job, you will need these:
http://www.yellowjacket.com/AUTOProducts.asp?t=AUTO&l=33&c=114&p=105

[Karl Hofmann]

Just to add to what Brian has already said, if you charge the system with the engine running then charge as a vapour through the suction side though I throttle the manifold valve with the engine at tick over. Alternatively you can charge as a liquid and warm the refrigerant bottle to charge the last little bit but always remember to turn the compressor a few times before starting the engine to ensure that the compressor isn't slugged with liquid.