1999 S70 Vacuuming and Recharging A/C

volvooh · Post by **volvooh** » 01 Apr 2015, 08:09

Starting a new thread on this topic. I am in the process of a major A/C overhaul replacing the compressor, condenser, dryer, orifice tube and several hoses. I have several questions:

1) To vacuum system, there is no high side connection, correct? It will just be connected to the low side?

2) I assume that anything in the system- moisture and remaining pag oil- will be removed as a result of the vacuum, is that correct? So when adding PAG oil, before recharge, what is the best method for this, and how much assuming a completely empty system?

3) How many pounds of refrigerant should I plan to add? (also just an fyi, in this case the system is completely empty.

4) Lastly- are there any special tools needed to remove the orifice? how is that line broken in order to gain access to it?

Post by **abscate** » 01 Apr 2015, 12:03

Just low side, correct

PAG will remain in, it has really low vapor pressure. There is a recommended amount of PAG to add for each major component you replace. A bit too much PAG is ok. I think 200cc is the total in the system

R134A capacity should be on your sticker in the engine compartment. You add a bit more for cold climates...850g

The orfice is removed by breaking the 19mm union in the evaporator feed line - its fun to work down in there .....ugh.

volvooh · Post by **volvooh** » 01 Apr 2015, 12:59

Would it be better to add all components (dryer last of course) pull a vacuum and after ward add pag oil followed by Freon to the low side port?

Post by **abscate** » 01 Apr 2015, 13:24

I did this.

Put it together.

Pumped it down for 3 hours, then watched it for a day to see if I lost vacuum.

Opened up dryer, added PAG

Pumped back down to vacuum for 15 minutes

Added Freon to spec.

I used the Harbor Freight AC gauge set and pump, regularly 199.99, free after you apply 10 coupons to it

Seriously, I think I spent 50 total after all the specials. Ive done 4 cars with it now, so it owes me nothing

Post by **Ozark Lee** » 01 Apr 2015, 14:17

I just buy the pressurized PAG oil and never break the vacuum at all. The vacuum sucks it right out of the can if you turn it upside down.

The rub is that they typically sell the pressurized PAG oil by ounces of weight (grams) and the specs for various component replacements are ounces in volume (ml). I had to come up with a conversion factor the last time I did a major service that required me to add oil. It was fairly easy to find with a Google search.

...Lee

Post by **jimmy57** » 01 Apr 2015, 14:21

The recommended practice for oil addition is to scatter it. System needs 6.75 ounce dry and you're pretty much there with what you are replacing. 2 ounces in compressor suction (larger one) port, 3 ounces in accumulator, and a bit under 2 in the condenser would be good. Too much in one place could cause a hydro-lock of compressor. If you find you have a leak somewhere by checking for vacuum loss as suggested then it will not get away if you need to open a connection to put in another o ring. Vacuum will not pick any of it out of the system.
1 pound 13 ounces of R 134a. If using cans then it will be a bit under 2 1/2 cans at 12 ounce per can. You can use a postal scale for the last can and watch for 5 ounce weight reduction.
Cans up for adding to be safe. A heater blowing on cans speeds up the flow and 100-120 degree heat is the way most machines speed up the flow.