AC System Top-Off: Straight Freon or Freon/Oil/Sealer?
 

I've seen previous comments indicating that when the AC system (R134a) is refreshed (just a freon top-off, not a full evacuation and recharge) that only straight freon should be used - not the commonly available freon with dye and leak sealer.

Why not?

That was not my question, sir.

Randy, the stuff you see most of at the auto stores has all of this nifty, neat, stuff they added with bright labels, to give people a feeling they are getting more for their money.

Just find some basic stuff and go for it.

If you are just topping off the system. Its most likely because its not cooling up to par. Just add strait refridgerant and dont take up volume with other stuff that does not contribute to cooling effect. Just my 2 cents.

Just use freon, no sealers, the dyes you can buy are not very good.
If it cools good, just top it off.

So no particular reason not to use the stuff containing sealer?

Besides that it doesn't work?

Nope.

If it makes ya warm and fuzzy go for it. Its not going to hurt.

Because the leak-sealer can plug up other A/C system components. This happened on my Isuzu a couple of years ago. I had a small compressor leak so I topped off with 134a with dye and leak-sealer. It did the trick nicely - at first. A week later, the A/C was totally dead again. I brought it to the dealer and they found that the dryer (or the expansion valve?? don't recall) was plugged up - from the sealant! Rats! At least it was a kind-of cheap fix for that vehicle. After that, I've only used 134a + dye.

The dye is harmless to use, and I prefer to use 134a with dye so that if you decide to (or finally have to) fix the leak, you will already know where it is.

Good luck!

Other than the fact it has plugged up 2 of my $$ recycle machines, and turns hard as a rock when exposed to air, like if you have a line burst and will plug up expansion blocks if it does.

Just tell the guy that does the next service on it that you put sealer in it.
If he is like me he is going to say "Sorry, I can't and wont help you"

I see no reason not to fix the problem and leave the mechanic in a can alone.

Randy--

A lot depends on where gas is leaking. My car sits a lot when I'm away on business and weeps from the compressor seal. Oil doesn't escape from an idle system; if it was carried by the leaking gas, it would sel the leak, at least on the mechanical seal in the compressor. If your car leaks while sitting and not generally while running, don't add anything except refrigerant to the system. The rest of that stuff is just there to confuse the expansion valve and plug things up. On the dye additive, it only works for you if the system and connections have been cleaned by scrub nurses, and the areas around them have been isolated by hermetic seals. Only then, with a good UV light, would you be able to see and isolate the source of the leaking... oil. Oh yeah, the dye is carried by the oil, so it generally won't leak out of a resting system.

I love the claims made by additive-laden refrigerant recharge packages, like extra cooling capacity thanks to our secret aditives, stuff like that. Pay no attention to the man behind the curtain! Just get the regular stuff.

I've posted in the past about some housekeeping issues around recharging, particularly for people using the little can-tapper kits. Bottom linne message is that you want to avoid pushing air into the system. So purge the hose with liquid before you charge, getting as much air out of the hose as possible.


Rob is temporary caretaker of my sniffer leak detector. It's available if you want to isolate the leaks.

Randy-

I'm housebound with 3 kids this weekend since the wife is on call - I've got Bob's sniffer, some r134a gauges and some r134a if you want to make the road trip and see where you are pressure-wise and potentially leak-wise. Or you can just top 'er off and see if that holds things for now.

Thanks, guys.

It is a very slow leak - need to add about 1/2 can per year.

I will stay away from the stuff with sealer in it!