Air conditioning newby... DIY your pay someone else?

[jangell]

That is an awesome write-up (I still haven't read all of it yet, but I'm getting there). I know my A/C is slowly leaking refrigerant, and while the A/C shop couldn't spot the dye we added to the system, they did notice oil on the pipes from the evaporator. I hadn't realized just how much of the car had to be dismantled to get the evaporator box out. I think I'll be following your diagnostic steps with the vacuum pump and other suggestions about using nitrogen and soapy water to track down leaks before I tear apart my dash.

Thanks!

-- Joe

[kings1527]

That is an awesome write-up (I still haven't read all of it yet, but I'm getting there). I know my A/C is slowly leaking refrigerant, and while the A/C shop couldn't spot the dye we added to the system, they did notice oil on the pipes from the evaporator. I hadn't realized just how much of the car had to be dismantled to get the evaporator box out. I think I'll be following your diagnostic steps with the vacuum pump and other suggestions about using nitrogen and soapy water to track down leaks before I tear apart my dash.

Thanks!

-- Joe

Thanks! I'm glad it's helping you along.

As far as detecting leaks go, pulling a vacuum works well for moderate to large leaks but sometimes it won't pick up very small leaks. If you don't find the leak with a vacuum, you might want to consider pressurizing your system with nitrogen and see if you can find it that way. Some people use compressed air and then listen for where it's leaking. Compressed air has moisture in it but if your system has been void for awhile, you should replace your accumulator anyways so it shouldn't matter. Otherwise, nitrogen might be a better choice. It seems like you're already up on all that.

You might also want to think about using a sniffer for an evaporator leak. Take the sniffer and run it at the center vents to see if you get a solid reading. Sniffers can give off false positives but just another tool to use.

If it comes down to it, replacing the evaporator isn't all that horrible of a job. It just takes time.

[jangell]

My leak takes about 3 months to evacuate the A/C system. The last time I filled it was the beginning of summer 2012, and it was empty by the fall. It's been empty since then. I don't know how large of a leak "three months to empty" is, but I can try pulling vacuum first, since I'll need a vacuum pump anyway.

I do have a dinky air compressor (a portable, light-duty unit maybe 2 gallon capacity); its pressure gauge goes up to 220 PSI, but that seems optimistic given other posts that suggested a max of 100 PSI from an air compressor. I'm pretty sure I'll be replacing the accumulator anyway, so if I can get away with just using compressed air and an R12-to-whatever-an-air-compressor-is adaptor and some soapy water, that would be great.

Since my system is already pretty much evacuated due to leaks, I'm not sure if a sniffer would find much, would it?

As for pulling out the evaporator box, at some point I plan on doing some kind of custom center console that includes replacing the HVAC vacuum actuators with electric servos as part of a computer control thing. Having to pull everything apart for the evap will just shift my timetable a bit.


Random idea: It occurred to me that nitrogen is smaller than the R134 molecule and is tested at higher pressures than the A/C system normally runs at. This implies that if I evacuate the system and replace the compressor with an R134 model, then (in theory) I should be able to run R134 without any modifications. This of course assumes that I could plug all the leaks without replacing half the system anyway. This is only a theory, and I've heard of others running R134 in otherwise unmodified R12 systems, which is why I was thinking this might work. That and it's a lot easier to get R134 than R12, although I did get a few hits for R12 on a Craigslist search. Even so, there is a local shop here that can do R12 if I leave them the car for the day, but I'd rather do it all myself if I can. Also, I'd have to find a place to rent a nitrogen canister...

Thanks again!

-- Joe

[Bitsyncmaster]

A 3 month leak would probably show up with a "soap" test if the leak was at a fitting. If your hose is deterated you will never detect the leak since it's spread over such a large surface area. Just use a little freon to pressure test the system (unless you plan to go into the AC bussness).

My 2 month one can leak turned out to be the short hose from the condensor to the accumulator. Don't know why that hose deteratated more so than the other hoses but it did. I used that old hose to flush my condensor again and I could see black film in the solvent.

[jangell]

A 3 month leak would probably show up with a "soap" test if the leak was at a fitting.

Good to know.

If your hose is deterated you will never detect the leak since it's spread over such a large surface area. Just use a little freon to pressure test the system (unless you plan to go into the AC bussness).

So, even with a 120 PSI nitrogen test the hose would be leaking so badly that you you wouldn't get the sudsing? How were you able to figure out that your hose was bad?

As for using a little freon, I guess you mean to get a can of R134 and see what leaks out? Makes sense; technically illegal to let it into the atmosphere, I guess, but it is safe stuff and it's easy to get.

Thanks!

-- Joe

[Bitsyncmaster]

So, even with a 120 PSI nitrogen test the hose would be leaking so badly that you you wouldn't get the sudsing? How were you able to figure out that your hose was bad?-- Joe

Was the last hose not replaced. So trial and error.