2000 Montana AC Leak Detection

[kcarlen]

Hi people, I have searched the forum and have found similar situations with other owners, but would love to hear about any new information.....

I have a 2000 Montana with the rear AC.

Over the past few years, I have been adding Duracool as needed to get the air cold. All went well for the last few years, but last year, the charge only lasted for about 1 week, then stopped. I assumed that I had a leak somewhere.....

This year, I recharged the system to 45PSI, ( 1 Can of Duracool and 1 Can of Duracool Sealer). The thing still doesn't produce cold air...although the compressor seems to be running and maintaining 40PSI. As mentioned in a prior post, this figure is misleading, and could be caused by air being trapped in the system.

"Each can of duracool has 6oz of gas and is close to 1lb of r12 or 14oz of 134 but you still need to fill using pressure and vent temps to get good results."
Duracool Converstation

http://www.peachparts.com/shopforum/...ad.php?t=72758

I am Leary about adding another can...thinking that the thing is all going to leak away.

Does anyone have any good history about where the leaks occur on the Montana?

I have looked at most of the joints, and sprayed soapy water on most of them, and cannot find an actual leak anywhere!

What would really be helpful is an AC piping diagram of sort, does anyone have one that they are willing to post?

I have heard through another thread that the REAR AC condenser could be the culprit, or the bottom of the front one too....but I don't see anything.

Today, I ripped the computer and air filter box out in hopes of finding a leak somewhere under there....it sounds like a hissing from around this area when the compressor has been running.

Anyone with any additional information....please help! I don't want to spend much money on this van....again!

[consultIII]

if the duracool or sealer has fluorescent dye in it (check the can) you could use a black light (about $30 at a jobber) to locate the leak. Common leak points I would start with are the condensor which may have taken a impact from a rock and any spot in the rear line that has foam over it for impact protection. Moisture trapped under the foam causes rust & pinpoint leaks. min static (system off for 20min) pressure should be at least 50psi with r134a.

[PDESORM]

My 2004 Montana had no AC pressure when I bought it used. Took it to the shop and they pressure tested it and filled it, saying everything was OK. A week later, it failed again. I bought a fill-kit and after filling, checked for leaks and found that the needle in the fill-valve was sticking! Gave it a flick and that was it.
Make sure the middle of the compressor fly-wheell (the clutch) is turning when the AC is on. There is a built-in safety that kills the clutch when there is not enough pressure to prevent the compressor from burning out.
Good luck!

[kcarlen]

Thanks for your help guys.
I will check the filler valve as well...I really didn't check that...
But, I would have thought that I would see or hear it leaking there..
Is the dye a neon green colour? If so, I can see it with the naked eye at the filling valve.

[PDESORM]

Originally Posted by kcarlen

Thanks for your help guys.
I will check the filler valve as well...I really didn't check that...
But, I would have thought that I would see or hear it leaking there..
Is the dye a neon green colour? If so, I can see it with the naked eye at the filling valve.

The dye in mine is fluo-green. Some green will show at the filling valve no matter what, especially if some leaks out as you attach or detatch the nozzle. When mine was leaking, I could actually see it bubble after I removed the nozzle.

[kcarlen]

I think that I have found the leak.
It is at the filling low-pressure schrader valve, as other poster's have mentioned.
It is so minute though, i can barely see small bubbles appear over a 10 minute time-frame.
I guess that I need to have this valve replaced....I have read on another thread that these kits can be purchased through auto suppliers.

If I leave my fill quick-disconnect fitting in-place, I can maintain my static pressure in the system, (about 65-75PSI) with the engine turned off for so far a period of 2 days.

The air is now relatively cold, and I have added 3 cans of Duracool, from a 0 PSI state.
On the factory "Duracool" gauge supplied with the fill kit, while the compressor is running the reading is between 28-40 PSI. (Or the Blue range).

Does anyone know if I should be adding oil to this mix, or what is the relative amount that I should be putting into a system with the rear AC components?

Thanks all for the help so far!

[dewaynep]

I wouldn't add any oil since the loss of oil in the system due to the schrader valve leaking would be miniscule. The more oil, the less room for refrigerant, the less cooling effect. The schrader on the low side is a very easy one to replace, however, you will want the system completely discharged so the valve and oil and dye don't come flying at your eyes when you unscrew the valve core. You could just try tightening the valve core a little and see if that helps.

[brcidd]

Your leak is probably not at the fill port-- a good cap with a good rubber sealing element will seal it. I have fixed 7 or 8 U-vans with leaks in the high pressure liquid line to the rear system- at a point just above the gas tank filler hose-- look under the protective insulation that wraps around the 3/8 inch line-- you will see imperfections in the tubing- lamination and then the leak- look for oil residue dripping, once you tear the insulation off the line-- I use swageloks to cut out the bad part and splice in the swagelok connector- works great and no need to replace that 12 foot line.....

[JabbaTHutt]

Well mine got a leak a 2 years ago, it happened in the rear lines, some electrical connector was resting on the HP side and with the salt here in the winter it created a some kind of current and you could see where it burned a hole in the HP side pipe. We mixed up some brown fridge epoxy and put it on it, a week later we put some more on it and then filled the system, it lasted a month or so then died again. This year we found that that the LP side pipe that comes from the back was rubbing on the body where it takes a bend down to head to the front, so we cut it out towards the back and towards the front and put in a 5 foot section of new pipe, we knew it leaked there because one of the cans I put in had die in it. We could find no other leaks even with the light and the glasses on.Well a month later its not working again so first chance we get its back up in the air, the epoxy connection isn't leaking, our new pipe isn't leaking, nothing at the front of the van is leaking but there is a clamp, the last one before it goes up the firewall, just covered in die, there is also foam covering the LP pipe from there up into the firewall, we started to cut it back and it is just full of die, so off it all came washed it down and found a leak, I have put in 1 big can and a small can in it then after we messed with it, ended up putting a hunk of clear hose over the hole and then a hose clamp over it. Had if up in the air yesterday for an oil change and ya its leaking a little, we can see the die but the air is still working. If you can get a can with bright green die in it you won't need a light to find the leak if it doesn't work after a week.

[kcarlen]

Well, to the contrary of some of your opinions, the leak IS in the fill valve.
I have had AC for the last month, leaving my charging coupler and can attached to the fill point.

I actually only did this temporarily to check and see what the pressure was doing while sitting overnight. I noticed that the pressures did not drop significantly, an thus tie-strapped the hose and can to the engine and tested it for a week. No loss, and the AC works.

If I take it off, the refrigerant will leak within 2 days and I will be without AC once again.
My plan is to wait until Sept, then vacuum down the system and have the fill valve replaced.
Then, hopefully all of these issues disappear.

Thanks to all that provided input, much appreciated in this 35 deg C humidity.