AC recharge question - 00 S70

neworleans · Post by **neworleans** » 26 May 2017, 09:11

Hello all,

I am planning to vacuum and recharge the ac system on my 2000 S70.
The plan is to vacuum the system from the low pressure side which is the only one available I guess and charge about 0.75kg R-134.
Will I need to add any oil and am I missing any steps?

Thanks in advance.

Post by **abscate** » 26 May 2017, 11:10

If you haven't had major component failure I would not add PAG. Look up the exact amount for your car - in hot climates you want to undercharge a little, maybe 10%.

For us inexperienced AC people, once you get to about 80% of charge, monitor the temp delta (car at 1500 rpm, recirc on, fan high) and aim for 40F temp delta adding a bit at a time.

Good thread on this by jimmy in Fora

Post by **Ozark Lee** » 26 May 2017, 13:03

If you have a refrigerant scale, or any other good scale, then that is by far the preferred method.

What is the back story? Refrigerant isn't something that you would normally just change. If the system is flat (0 psi) then you will also need to replace the filter-drier but even before that you will need to figure out why it is flat in the first place. In other words, you need to try to find the leak. If you do change the filter-drier the you should add PAG oil. The system R-134a capacity is actually 29 ounces which is about .82 kg. The book spec on PAG oil is to add 3 Oz when you replace the filter-drier.

My biggest problems for leaks on the 70 series has been the Schrader valve which is the one that is the most difficult to detect. The UV dye will always be in the Schrader valve since that is where it is introduced to the system in the first place and a vacuum leak test won't reveal anything since the gauge set is hooked up to the valve to monitor the vacuum level. The other popular leak area is the evaporator but less so on the 70 series cars than the 850s.

If the leak is real slow then you can often get through a season without fixing it but fixing it is always the preferred method. At least R134A (HFC) isn't as nasty as the old R12 (CFC) systems when it comes to environmental damage.

...Lee