99 Suburban Rear Evap Help

[scjarena]

I'm working on my 99 Suburban which all of sudden developed a quick leak. It was working just fine one day and about a couple hours later it quit. I pretty certain I've isolated the leak to the rear evap or rear lines, which I determined by isolating and pulling a vacuum on the rear evap and lines at the firewall under the hood and checking how long it holds. I would like to know for sure where the leak is before I proceed. I do have dye in the system. I hate to tear into the nightmare of the Suburban rear AC until I know exactly where the problem is. Anyone have any tips on where to go from here? Any help would be appreciated.

[bohica2xo]

Jack it up & look at the lines to the rear evaporator with your UV light.

[GM Tech]

Rear lines usually leak at the grommets that hold them in place- most likely near wheel where the rear wheel throws salt and debris. Corrosion takes place- 9 times out of ten, it is the 3/8 liquid line that leaks. Those lines can be fixed- cut the bad part out and use a swagelok connector to rejoin them. The dye will show you where it is at exactly.

[scjarena]

I've looked over the lines with UV light and don't see anything yet, so I pull the rear evaporator out see no dye on it or at expansion valve connections. I do a quick pressure check while evap is water and see no leaks, so I guess leak has to be in the lines. What a pain.

[GM Tech]

With rear systems 99% of the time it is in the lines- I would never have looked at rear evap- they are just that rare to leak--there should be dye dripping from the leak- and bubbling when charged- I've had people tell me they see a big green spot on their garage floor- at the rear of vehicle! Yes, that is the oil with dye dripping...from the liquid line (3/8")

[Cusser]

What's the mileage and condition of such 18-year-old Suburban? Worth significant $$$ to fix?

Consider blocking off the lines for the rear AC unless you constantly have 3rd row passengers in hot climate. We had 1994 Suburban and by the time the rear AC stopped working (I assumed it was rear expansion valve), we no longer had kids around to transport, so we just left it like that, was fine (Arizona, too).

[scjarena]

What's the mileage and condition of such 18-year-old Suburban? Worth significant $$$ to fix?

Excellent condition with a rebuilt engine and trans, so its worth saving. I thought about buying a newer one a couple years ago, but after looking at the prices, it was way cheaper to keep mine going for a little longer. I live south of Houston, so at times the heat and humidity will kill a person.

[bohica2xo]

Yeah, I have seen the price on new trucks too...

The lines can be repaired. Looks like you have begun isolating components. Pressure check the lines individually. If the leak is not big enough to be heard, run the pressure up to 125 psi & try some bubble liquid. Use the good stuff like the gas company uses - Sherlock is one brand. Most places that service propane equipment sell it.

https://www.toolexperts.com/liquid-leak ... ction.html

http://www.amgas.com/ltpage.htm

[scjarena]

Finally got back to working on this. I found the leak in the low press line behind the wheel well.



Since the leak is in the tubing bend, I'm considering cutting a few inches back where the line is straight and get a junk yard piece replace the bad end and connect with a swagelok fitting. Maybe welding the leak would be the best fix.

What would you do?

[scjarena]

I have the AC system cranking out some cold air. As for the leak, I ended up using some AL822 flux core to solder up the aluminum. It worked great, I would really recommend it if you haven't tried it.