2008 RX350 230,000 miles

Refrigerant was leaking but at a manageable level (half a can every couple weeks). But it has now take a turn for the worse. I put enough in to feel cooling last evening (green zone on the gauge) and this morning it's too low to feel cooling. In this situation I am careful not to connect while running lest the low side pull a partial vacuum and suck in air. It's not totally gone as connecting when not running when the entire system is equalized does put me in red overcharge on the gauge which is expected when not running. But in 12 hrs enough loss that it stopped cooling.

I have injected some dye to see if I can get an idea of the leak location.

Given the mileage, I don't think it would make sense to put thousands in to restore A/C. But I'd like to at least try a sealant. The junk at the store is just about softening gaskets etc. But I know there are some professional grade sealants which will actually seal small openings. If this is a compressor shaft seal leak it probably won't work. Any recommendations? "First, do no harm." I don't want something that will ruin everything and preclude a proper repair if I do choose to go that route.

 

Hi, Get it checked out!
It's been my experience from working on cars a long time, that's its probably an AC Compressor hose/line.
A small leak on the line/hose would take a couple days to leak down.
I wouldn't use a sealant unless the repair cost's warrant that.
Once you use a sealant, it's always going to be in the AC system.
Most of the time AC repairs can be Reasonable, and Don't have to Kill your pocketbook!
I Hope you find the refrigerant leak!

 

If you don't think its worth it to fix the a/c at 230K, just drive it as is or sell it.....You don't know as it could be a condenser or O-ring at the least...

 

I'm going to get it looked at. I can say that the dye has not revealed anything. I did make a bit of a mess injecting it but I've got that cleaned away and nothing is obvious. Nothing on the condenser (not the front anyway) and nothing around the compressor clutch where I'd expect to see it from a leaky shaft seal and also nothing of note on the tubes and hoses other than what's left of my mess. That could imply a leak at the evap which I can't see but a pro with a sniffer might detect. If I did sealant it would not be the stuff you get at the store that softens O rings and gaskets but the pro stuff that seals on contact with air or the moisture in it. That would probably not help with a compressor shaft seal but might seal a pinhole in the evap or other places.

 

When you have a large leak like that it will be visible unless it's the evaporator, you should be able to see it somewhere using a flashlight unless your engine compartment is a mess.
How did you inject the dye?

 

A biue light is what you'll need to see the leak is from the dye......

 

Took it to a tech who added more dye as he wasn’t totally certain my attempt had gone in. Could not find a leak at first but eventually determined it was leaking at the low side service port so he replaced the schrader valve. But it’s still leaking at a good clip and we cannot find it. I guess it’s gotta be the evap. And just not worth the massive labor bill on such an old vehicle.

I did get Nu-Calgon sealant but have not put any in as I think it would fail on a large leak.

I’ve not detected dye on the condensate water but I’m not sure how miscible it is. Or maybe a leak in a return bend would not show up anyway. Tempted to try to blow detergent foam in somehow, maybe where the cabin filter goes just to try to coax dye out. Or probe with a tiny camera I have which is the size of a pencil eraser. I would add a UV LED. Any chance of getting a view of the evap like that? It would not make it more fixable but at least I’d know for sure.