Pressure testing a/c questions
 

How do you find someone who can actually pressure test
a/c system???

They all want to VACUUM test with dye and use 134a

How bad is dye for the system?

Vacuum test with dye? surely they won't find a leak that way! The dye is only useful under pressure. I can't believe there is no shop around you that wants to do it correctly. The only thing I can think of is that they want your $, and for you to come back when it all leaks out. I use all three methods for finding leaks: Nitrogen and soapy water for pressure testing, dye with UV glasses and light, halogen leak detector ("sniffer"). If anyone suggests to have you pay them to leak test with vacuum, politely say no way and walk away....Rich

Almost any shop
 

dealer or independent should have the basic gauge set that is needed for pressure testing.

Beware those that try to sell you on R134 filling. Basically, an ac gas fill is forever unless there is a leak or servicing that requires evacuation. When I bought my W123 the ac was inoperative. I had it repaired and converted to R134 at the same time. You cannot simply fill with R134. You must change all components including hoses. R134 has smaller molecules than R12 and will leak out. You need the correct hoses, o-rings, dryer, and compressor. After you change all that, it still will not be as good as an R12 system unless you also change to a good cross-flow condensor (spendy).

If your R12 system is still working, keep it.

OK, my wording was waay stupid.
I would prefer to have the DIESELS r12 system pressure tested FOR LEAKS, as I have read here its the proper way

The people I have talked to are saying they will vacuum down the system (understandable FOR REMOVING MOISTURE)

BUT THEY WANT TO USE DYE IN IT AS WELL TO LEAK TEST and then do the r12. Which of course they are trying to tell me its waay expensive, which I know its not. Then try to tallk me into 134 which I really dont want

I have quoted the proper way to leak test is pressure not vacuum, and they get flustered and rude.

Anyone with proper gauges can pressure test it. Dye is good for visually finding leaks, but it needs to be installed in a system that is operational with some Freon pressure.

My car was converted to 134a by the PO. When I bought the car, a month later I had to replace the compressor, expansion valve, drier, pressure switches and hose. I left the 134 fittings but charged the system with Freeze-12. Fast forward to 2015, and the system has been flushed and now filled with Duracool. So much better than the 134 and the Freeze 12. R12 would have been best though, but it is too spendy for me.

Nitrogen or R152a and dish washing liquid in water applied with a small soft paint brush.
Look for leaks THEN pull a vacuum.

Otherwise, if there's a big leak you'll suck moisture in your new dryer.

Fortunately I have the 85, the condensor is supposedly the better of the lot of the 123s

Im just wondering about using dye in the system?
Ive read its a no no.

Since Ive gone to the trouble of purchasing NEW ac parts
I dont want to gum up the compressor or put added
Stress on it if its not entirely necessary.

What have your experiences been using dye?
Good? Bad? Yes? No?

I think at this point I may just have to do most all of it all myself
Just having a difficult time finding some one to pressure
Test.
Guess Im asking wrong questions
I will have to ask if they can test with nitrogen?

You're not asking the wrong questions; you are right on track. I got a nitrogen tank on Craigslist for not much $$ then went online to find a regulator and got an adapter at Tractor Supply (I think - or maybe from a welding supply place or Napa)) to hook up the regulator to a set of gauges.

You can get the nitrogen tank refilled at any welding supply shop (actually they just swap out the tank you bring in, with one that is fully charged; doesn't cost much at all and lasts a long, long time).

The pressure from the nitrogen tank is way too high to use directly on your ac system which is why you need a regulator and also an adaptor to be able to hook up the yellow line from a set of gauges to your nitrogen tank.

Nitrogen has other interesting uses too - I'm thinking about making biodiesel someday and I've read that a nitrogen "blanket" to take up the space otherwised occupied by oxygen is how to keep a drum of methanol from sparking off accidentallY. It will also keep wine from going bad.

Sounds complicated but it's really not. Also I do use the dye (with a nitrogen charge) to locate leaks. I also put in a tiny shot of R22 (house ac stuff) or R12 with the nitrogen charge and use a "sniffer" (InfiniKon Tek Mate) to help with finding leaks.

Chasing leaks can be a real adventure and I am sometimes pulling my hair out even after checking with dye, sniffer, and bubbles. Usually when the leak is so elusive it's a hose; and on these old cars it's not a bad idea to go ahead and have all new hoses made up- take your original hoses to Napa or to a shop that does a/c hoses and they can rebuild your hoses with existing fittings and new rubber.

If you feel like riding up to the shop one weekend let me know and I can help you with the testing and r12.

Ok, I understand now what the shop is attempting to sell you...


They don't leak search... They recharge, then use dye leaking as the search. Bummer.

All home HVAC contractors have nitrogen with them, it's required to install new equipment. Get yourself a set of automotive gauges, and call a service tech to pressurize your system up to 150 psi, and search for yourself.

Dye is not a problem for the equipment, it is fine in a system... It's leak sealer that gums up the equipment and should be avoided.

I was hoping the a/c god/gods would speak thanks vstech!....thanks all!

Answer me this question, a/c gods, ...... of every a/c system ever filled, properly or not, in 100 years, where will every ounce of freon end up?
Ill answer for you. In the atmosphere.....
You keep ANY car for 50 years....it WILL leak ALL of its freon eventually.
There is no "forever fill" r134a cannot , within financial reason, be contained indefinitely.
I asked this to an instructor in a refrigerant class one day. His face turned red, then he asked the class if my statement could be found false. No one raised their hand. So he agreed
Just a thought....

The dye will not hurt your compressor. Most compressor oils come w/ uV dye in them. PAO 68 is the best oil today. Re a conversion, I suggest avoiding R-134A since it is soon to be outlawed. Hydrocarbon refrigerants (Duracool, Envirosafe) work great, but read all the imagined horrors on the internet first, then weigh against the fact that no such fire/explosion has been reported from millions of cars using it (except an AC guy in Australia who rigged a test).

Going with r12 for sure, too hot in florida not to do it the right way

My personal feeling is these old systems were designed to operated properly with R12 not 134 so your best cooling is going to be with R12. I got lucky and my AC issues were in the control side not the refrigerant side. Doing the nitrogen pressure test is a good idea. When I do that at work I hook up my gauges and then run in the nitrogen and then close off the feed but keep the gauges attached so I can watch over a few hours to see if there is a pressure drop. If you can drive up to engatworks shop It sounds like that could be your best bet. It sounds like he has the equipment.