DIY AC Service/Recharge?

[OK-944]

When I purchased my ‘87NA in 2019, its service records (which are complete from day one), indicate that since the car was converted to R-134 a number of years ago, its generally gone in for an AC service/recharge every three years.

And, having last had this service done in 2021...the car is now, like clockwork, no longer blowing cold. (and yes, I’m very diligent about running the AC at regular intervals during the colder months, to keep things lubricated)

At any rate, instead of bringing my car in for this AC service, I’d like to perform this service myself…but need a bit of guidance from those on this forum who’ve either done this themselves, or who might at least be able to point me towards some good information on how to do this…hopefully that which is “944-specific.” Thanks!

[grendiers]

Two items you’ll need to do a proper service; a vacuum pump and a set of A/C gauges. Both can be purchased at Harbor Freight. Also a dye to find the source of your leak. A simple o-ring at any connection might be the culprit. Or the condenser up front is leaking. Or the compressor itself is leaking. Take a look at Griffiths.com for parts and information to fix your leak. There are easy to follow instructions on how to replace the condenser for example.

[Jfrahm]

I have the above gauges and vacuum pump. I have done work with a basic gauge and fill setup and no vacuum also, with some success. In that case the system still had a little pressure in it so had not gotten exposed to air/water vapor. The other things that are critical are AC dye, dye detection flashlight and a clean system to observe.

My suggested plan:
Search for evidence of a leak, dye from the last recharge. Unfortunately the fill port might have dye around it and might also be the source of the leak. But you can at least look it over. If you do not see any dye there maybe there isn't any in the system. Burp a little gas out and see if it's got dye in it. There is probably some residual pressure.

Look hard at the condenser and fittings for leak detection dye, as well as the rest of the system.

Refill with a can containing AC dye, I have gotten this at Walmart for a reasonable price. If your system has been converted including the fittings it should be straightforward to add gas/dye as per the instructions. Be somewhat bold with the pressure as well as observing the temp/pressure chart for 134a.

Clean up any dye around the fill port, plus the inevitable spatter. In the dark you should not find any AC dye when you are done.

Enjoy the AC and check it in a few months for dye. It might be hard to find the leak as it is slow and might not push out a lot of dye. I had a condenser leak I thought was bug guts but was just a trace of AC dye.

[djnolan]

Two to three years seems standard for these systems. Running them periodically during the winter will help but the 134 will leak out one way or another even if there is not a detectable leak. I have a DIY setup, but one problem is you don't have a way to recapture any freon still in the system per any environmental regs. If you don't evac, it makes it hard to estimate how much freon to refill with to get the proper pressures.

I used to have a deal with a local shop that did a evac and refill for around $100 with a professional setup. I had them evac and recover the system for 20 minutes, then turn off the evac pump, let it sit for 30 min and check the pressure to see if there is a leak. And then run the evac a 2nd time to get any residual freon, oxygen and moisture out. Then refill it with a full charge to ensure the correct pressures. One concern is that the shop will want to add oil and too much oil can result in overcharging and high head pressures. So I decline adding any more oil. I also decline the other extras like leak check and do this myself as JFrahm described. I also add BG products Frigi Quiet to get the temps a little lower.