GRUWEZ

I'm planning on refilling my 964's A/C system with R134a. I would also like to top up the refrigerant oil. I do not have a fancy machine to do this, only a two gauge A/C manifold, a vacuum pump and of course all the hoses and fittings.

Is there a way I can manually top up the refrigerant oil?

Thanks for the feedback.
Rik Gruwez

Computamedic

If you are changing from R12 to R134a you MUST NOT merely top up the oil - you HAVE to change the oil completely. The oil used with R12 is not compatible with R134a. You have to use PAG46 oil with the R134a. If you evaccuate the system it will draw out most if not all of the old oil.

Regards

Dave

Kahdmus

Reading is a lost art....

Steve Weiner-Rennsport Systems

Hi Rik,

I don't know whats available in Belgium, but here in the US, one can buy small cans of R134a with, or without the ester-based lubricant that you need.

Thats the only way you can do this without evacuating the system to add a measured amount of oil.

BlueHeeler

In Europe he might be on HC12a, so dumping in R134a could be bad depending on what is already in there.

IIRC Europe is phasing out R134a.

GRUWEZ

Thanks for the feedback. The car has an original R134a setup. All I want to do is to refill it with R134a and add the required amount of refrigerant lubricant. R134a is still readily available in Belgium.

Regards,
Rik

springer3

There is a special tool for adding bulk oil. If you can find the cans that fit on the charging hose, that is the more convenient approach. It is not correct that evacuating the system removes the oil. The gas evaporates, and the oil remains in the system.

dfinnegan

Then how does the oil get removed?

springer3

Oil collects at the low points, and particularly in the compressor. It is best to remove the compressor and dump the oil out. For the lines and the two heat exchangers, the trick I learned at an AC shop is to drop in a can of brake cleaner, and then chase it out with compressed air. It is a good idea to replace both the receiver/dryer and the expansion valve if you are doing a major change on the AC system. That leaves short runs of lines and straight shots through the condensor and evaporator to chase out the oil. Adding oil by weight is then possible because you know the inventory is zero.