Automotive Air Conditioning Information Forum

Hello,

If I use denatured Alcohol to flush my vehicles automotive AC system wil the alcohol necessarily dilute / contaminate the Vacuum Pump Oil so that it needs changing?

Thanks

If you have enough residual flushing agents to ruin your vacuum pump oil, your concern should be the oil in the AC system and a better flushing technique to remove it before the vacuum stage of the repair.

Tim wrote: ↑Mon Aug 12, 2024 12:43 pm If you have enough residual flushing agents to ruin your vacuum pump oil, your concern should be the oil in the AC system and a better flushing technique to remove it before the vacuum stage of the repair.

It's not really a question of how much flushing agent remains in the lines or if that is enough to ruin the vacuum pump. Of course it's desirable to have the lines and entire system as clear of contaminants as possible before vacuuming. It's a question of the physical attributes of automotive AC vacuum pumps. To determine if changing the oil may be a good idea during flushing or before long term storage to prevent corrosion.

The flushing procedure is tried and tested over time and works exceptionally well and is used by many. There is no way to remove 100% of the alcohol without vacuum so that it boils into a vapor. Thus the question. Even a Nitrogen purge doesn't remove 100% of all residual alcohol.
If you know of a way to remove 100% of the flush medium (without expensive shop equipment) prior to connection of a vacuum pump, please let me know.

let me re-phrase the question.

Is the lubricating oil in the vacuum pump subject to exposure to or mixture with the alcohol used for flushing or are they physically separated by seals so that they cannot mix?

Yes, every 10 to 20 cycles, depending on repair type.

Alcohol is the last thing I would choose for a flush. Tim, the site owner, has a pro flush available at www.ackits.com.
I would then blow the system out for several hours with dry air, ie compressor air with dehydrating equipment attached, such as might be used in an automotive paint shop. You could use dry nitrogen if you had it.
And the last thing you want is the flush found in the parts stores.

Some technicians will change their vac pump oil with each and every job. You can get to desired vac level faster and better doing this.

Thanks.

tbirdtbird wrote: ↑Tue Aug 13, 2024 8:51 am Alcohol is the last thing I would choose for a flush. Tim, the site owner, has a pro flush available at www.ackits.com.
I would then blow the system out for several hours with dry air, ie compressor air with dehydrating equipment attached, such as might be used in an automotive paint shop. You could use dry nitrogen if you had it.
And the last thing you want is the flush found in the parts stores.

Some technicians will change their vac pump oil with each and every job. You can get to desired vac level faster and better doing this.

I change the vac pump oil in my Robinair Vac pump after every use and have been doing this since 2007 on the same pump. It still works like new. The owner's manual for the pump also states to do this.