Hi, I am at a loss with my AC system, hoping someone here can help me out because I'm out of ideas. Cannot figure out where my AC system is leaking.

A little background info.. Truck is a 99 Dakota with the 3.9. A fresh charge on my AC was only lasting about a week and a half, maybe 2 weeks. I charged it with the dye and couldn't find where it was leaking, so I assumed it was the evaporator. My heater core was also leaking so I was going to have to pull the HVAC box regardless. So I pulled the box, replaced the evap and heater core, and have everything back together now.

I pulled a vacuum on the AC system down to 30 inHg, ran vacuum for about an hour, closed valves off to check for leaks. About an hour later vacuum leaked to 25 inHg. Left it over night and by the morning it was at zero, lost all vacuum. Ran vacuum and leak check again with a different manifold gauge set and lines to rule out possibility of a bad gauge set, but same results. Tonight I pressurized the system with nitrogen to about 100 psi and sprayed the crap out of every line connection and component with soapy water to look for bubbles and found nothing.

Any ideas?

 

Backside of the condenser?

 

Hi, thanks for quick reply. I guess that's a possibility, but I really soaked the condenser pretty good with the soapy water. I would think bubbles would be visible even if the leak was on the back side.

 

Maybe...... trouble is, ya good pull the radiator, unless you can pull the condenser out some?

Not leaking around the shaft seal on the compressor is it?

 

Not from what I can tell, can't really see too well with the clutch still installed. Guess I'll pull that off and check it out this evening.

 

Did you happen to replace all the old o rings? It may be at the connections or a hose. Do you see any oil residue? That can be a tell tail sign of a leak also.

 

Your compressor may be leaking out the shaft

 

Leaks are hard to track down. It's never a matter of if but more like when. O-rings, get a kit from rock auto, it includes all. If the evap is leaking an ultrasonic leak detector in the vent when the AC is on will tell you. Also the access valves, check the fitting caps as sometimes they don't seal well after a recharge. Rubber hoses sometimes lose their seal and can leak anywhere on the hose. Compressor seal like mentioned is always a culprit to be considered. I had a slice in a rubber hose that wasn't visible cause it leaned against the air box on a 3.9L. A hose barb install with some good clamps, been that way for many years now and holds tight. Keep looking.....

 

OH YEA forgot about the high low port Schrader valves very common spot for leaks you should always replace them.