Re: How long did you leave the system under a vacuum and how much oil did you remove...

Hi folks,

I have been searching the web all over and could not find a clear answer so hopefully some experts here can help me. Note: it is for a Honda 03 Accord (non-Boxster)

Anyway, with UV dye I found out my AC condenser is leaking (bad design) so I replaced the condenser and the receiver. The manual call for 25 ml (condenser), 10 ml (receiver) of oil (PAG 46 = ND-OIL-8??) to be added after I replaced them. It is straight forward. However, I also did a vacuum with my air pump to make sure there is no more leak. Someone on thew web said if I do a vacuum, it would suck out all the oil in the system and leave it bone dry. The total amount of oil is 160 ml (5 1/3 fl-oz). So simple question: should I add 35 ml (for condenser+receiver) or the whole 160 ml? I know I do not want to add too much oil,

Thanks for any help on this.

I know I can take it to the shop but the feeling of DIY is much more satisfying (and I know: I messed up most of the times but I learn it that way :-)))

Tony

Quote
boxster99
Hi folks,

I have been searching the web all over and could not find a clear answer so hopefully some experts here can help me. Note: it is for a Honda 03 Accord (non-Boxster)

Anyway, with UV dye I found out my AC condenser is leaking (bad design) so I replaced the condenser and the receiver. The manual call for 25 ml (condenser), 10 ml (receiver) of oil (PAG 46 = ND-OIL-8??) to be added after I replaced them. It is straight forward. However, I also did a vacuum with my air pump to make sure there is no more leak. Someone on thew web said if I do a vacuum, it would suck out all the oil in the system and leave it bone dry. The total amount of oil is 160 ml (5 1/3 fl-oz). So simple question: should I add 35 ml (for condenser+receiver) or the whole 160 ml? I know I do not want to add too much oil,

Thanks for any help on this.

I know I can take it to the shop but the feeling of DIY is much more satisfying (and I know: I messed up most of the times but I learn it that way :-)))

Tony

from the system? Also how much vacuum did you subject the system to?

The techs tell me they now leave the A/C system under vacuum an hour after having opened it up to replace something to check for leaks. I have seen the vacuum system in operation but I have not noted the vacuum level on the gage.

The system they use I guess guarantees all oil is removed so they can add the stated amount of oil and know the system has just the right amount.

I pulled the vacuum for about 1 hour. I only remove/replace the condenser and receiver. This is what confusing me: some one said the vacuum is to lower the water boiling temp so it can evaporate, it should not pull any more oil out from it, should it? Others said it will suck the system dry including oil. Any vacuum expert around here?

Thanks,
Tony

point of any water in the system and this (in vapor form) is removed. The low pressure is maintained for a specified period of time to check for leaks.

How the oil is removed depends upon the system. In some it is removed as part of applying the low pressure to the system. Instructions are to note how much oil is removed and to add this amount back and generally something extra, like another ounce or two.

In other systems the oil is removed through the suction port. This is done I guess after the system has been evacuated of any refrigerant. Then the system is subjected to a low pressure for the specified amount of time. At some point the oil is reintroduced to the system.

In yet other systems a specific amount of oil is added based on what was done to the system, what components were replaced.

Exactly what the steps are for the car, the A/C system, in question is something taught in the A/C service class for that car.

If you are on good terms with your local Porsche tech he may share with you the specific details for the car in question.

Here is the cut/paste copy of one of the exper on the web:

"Refrigerant oil will start to boil off at approx 175 microns I have NEVER been able to pull anything under 200 microns on a MVAC system the shaft seal will not hold I usually shoot for 500 microns and lots of times settle for anything under 700. Unless you have a unusually tight system and a very powerful deep vacuum pump you have nothing to worry about. It is always best to utilize a good micron guage to monitor your vacumm progress but I doubt that you will ever have trouble with MVAC applications pulling down low enough to bother the oil."

it makes sense to me so my own conclusion is : NO, vacuum for 1 hour won't remove oil from the AC system.

Tony

system indicates there is a specific setting of the A/C vacuum system controls to remove the oil from the system.

There is just a diagram, no words, with the switch/valve control graphic. How this system removes the oil I do not know but apparently it does using the vacuum in some way.

Perhaps some special gas (nitrogen?) or just refrigerant is used to help carry the oil from the A/C system to the vacuum pump and its oil catch tank. I encountered an A/C system in use at the dealer the other day but the unit is pretty much self-contained and I didn't have time to get a tutorial. While I would certainly like to know how it works I have no time.