Mystery AC leak - ongoing issue

[scootergmc]

A coworker's '05 has been to a reputable local shop for at four recharges over the past 2-3 years. They've dyed the system and checked for leaks, with nothing found. Any suggestions on possible *very* slow leak areas?

 

[BarryG]

I have the same issue with my 01. It can barely get through a summer after a charge. They have done the same dyed it more than once and can find nothing. only part that remains is the stuff under the dash as you cant see it to check for leaks. So for me until it wont last at all or my heater core starts leaking I am willing to charge it once or twice a year before I tear apart the dash to replace the heater core and evaporator at the same time don't want to do it more than once.

 

[DavidC]

A sniffer thru the drain will show it if there is one there.

Dave

 

[Tuesdak]

A sniffer thru the drain will show it if there is one there.

Dave

Maybe, maybe not. Slow evaporator leaks are difficult to find. It's almost a process of elimination to replace the evaporator if you have eliminated everything else. It took a couple years and several re-charges to finally get a 'hit' on the drain of mine. The running fan or even opening and closing a door will move enough air to hide a slow leak from the evaporator drain. Even an inspection of the evaporator itself for the leak may not show it after the leak detector hits on the evaporator drain. For some reason the evaporators on these trucks are a known common leak point vs. other makes. (As always do the Heater Treater doors and heater core while you are there. Suggest Mopar Evaporator and Heater core because of low quality short life aftermarket parts.)

Hard to find slow leaks do not leak oil or the dye. (Just because they are so slow they don't pickup oil or dye.) A car wash will clean off evidence of condenser leaks.

Some other slow leak areas are the system service valves and compressor shaft seals. The most common leak area is the service valves having a slow leak to the point that I replace them every single time I do any AC work - up to twice a year. The valves generally never show dye or oil and if they do you are asking yourself if it was from servicing. The high temperatures generally cook off the high side valves in extremely hot climates and any debris in the system like to collect around the valves and wait to mess their seal up during servicing.

After servicing the AC system use Windex and flood the high/low side service valves with it. If you get any bubbles the service valve is still leaking. If replacing the valve several times doesn't stop the leak replace the pipe the valve is in. (It's scratched, cracked, or debris impacted in the stem seal area.) Used compressed air to blow the Windex out when you are sure it's not slow leaking on you - you watch it for 5 min to be sure.

Compressor shaft seals are an inspection for excessive oil.

Hoses deserve special attention on troublesome systems of running the sniffer the entire length of the hose looking for pinholes rather than just at the common crimp leak points.

 

[RVTRKN]

Remove entire 134a charge and charge virgin R22 with dry nitrogen. Eliminate compressor from operating, just in case, and run blower on the lowest speed, stick sniffer into air stream on the outlet side. The reason for 22 is it's easier to detect, and any leak detector should work. My detector is the best in the industry, but a cheap detector should work, that's how I found my leaking evaporator in my 94 2500.