can not locate ac freon leak.
 

Hello all,

1989 v2500,,,5.7

This is my 3rd time trying to find this leak,,, after converting to sanden, the system will pull a vac and hold over night. But when charged it will lose the freon after a week or two.

I then charged the system to 100 psi and it will hold forever. I replaced a suspect oring and charged.. 2 weeks,, low on gas.


It is not charged to 100 psi again,, and it will hold,, but i know it will lose gas afterwards,


Is it possible a leak presents itself when the metal expands or contracts in the evap or condensor due to temperatures??? Any guesses

Re: can not locate ac freon leak.
 

Have you added dye to it . I had a similar issue with my 85 it ended up being the compressor seal

Re: can not locate ac freon leak.
 

at work we always add dye to the system and go over everything we can see with a black light before we release the vehicle back to the customer then we have them come back in a few days and check it again.

Re: can not locate ac freon leak.
 

It has dye and i can not see any traces, The compressor is a new real sanden 4711 sd7

my gauges are Yellow jacket analog,

I have had a charge of 100 psi for 4 hours now and still dead on 100,

shop has AC and temperature is a steady 72. I ordered a new condenser and evap core but hate to go through the work to not have it solve the problem..

it has all new Galaxy hose (usa) and fittings,

My gauge is hooked to the filter.dryer,,, I can only think that when i remove it the schrader valve is leaking and with the gauge it is captured,,, I have soaped it with no bubbles.. I might hook a hose to the shrader and put the other end in a cup of soapy water??

Re: can not locate ac freon leak.
 

I have had good luck with the R12 version of this: https://www.autozone.com/a-c-chargin...2oz/370967_0_0

Replaced a compressor in the mid 90s and used one of those cans with oil, leak finder, leak sealer and freon. Only needed a couple of cans since until something failed in the back of the compressor a couple of years ago. A large oil stain implies something that exceeded the capacity of the leak stop to fix. Planning on doing a Sanden conversion at some point.

Might be worth a try of the R134 version.

Re: can not locate ac freon leak.
 

Made it to the shop today,,, AC off,, temperature is 85 inside the garage,, The AC system has 106 psi,, It gained ~6psi due to ambient temp....

I will cool the garage back to 74 and see if it equalized back to 100psi,,, If it does,, I guess i will charge the system again and cross my fingers?

Re: can not locate ac freon leak.
 

I always change the service valves when I work on AC.

Giving the condensate puddle on the driveway a once over with the blacklight might reveal an evaporator leak.

Re: can not locate ac freon leak.
 

I had one slowly leaking down. pulled the valve core out of one inlet and it was missing the little sealing gasket on it. put a new one in and good to go.

Re: can not locate ac freon leak.
 

Update,

Charged the system and sure enough it leaked even after holding 100 psi for over 30 hours.

Today i started pulling it apart.. I removed the shroud and leaned the radiator back and sure enough there is dye on the radiator.. Using the blacklight and glasses i can see a stain on the condenser although not green. A few green drops appear on the engine radiator..

My guess is when it gets hot and builds over 200 psi a tiny pinhole leaks and the fan/wind pulls it into the radiator..

Anyway,,, pumping it back down again with a new condenser. I took a few pictures but it doesn't show anything


Chris

Re: can not locate ac freon leak.
 

In For results.

Re: can not locate ac freon leak.
 

the new condenser is smaller and thinner than the OEM. When i started the truck i noticed the high pressure nearing 375 and that is not average for this build.

THe fans shrouds were off and I hope that is the factor.. I will run the truck toady and check vent temps..

Re: can not locate ac freon leak.
 

Is the filter in the orifice valve full of crud?

What's your low side pressure running?

Re: can not locate ac freon leak.
 

Sorry,, i never saw your post. 30-40

Re: can not locate ac freon leak.
 

Another update,


After all that,, the freon was gone again this spring..

Again,, Charged with nitrogen to 200 PSI for 24 hours and it will not drop 1 PSI.


I pulled the evaporator coil because it was the only original part and sure enough, deep inside with all the lights off and the UV light i can see dye in the coil..


If ever another project ,, I will replace both coils at the beginning.

Re: can not locate ac freon leak.
 

Last update,

Charging now,,

FWIW, 36 ounce 134a in a v2500 burb feels right

I am at 32 PSI low side,, no high reading today,, oring failed in my coupler..

Inside wet temp 46 degrees

Chris

Re: can not locate ac freon leak.
 

I've been following this thread since its inception, and not once other than some dye, have I read the mention of a freon leak detector.. I've been working on automotive A/C systems for 50 years. The first tool I reach for is not dye, but an electronic leak detector and not once has it failed me. The most common item that leaks is the evaporator. it has to withstand the rigors of constantly flexing.. Next on the list is the shaft seal on the compressor and lastly is the O-rings and condenser.

Chris989, You've been at this leak for a year, have you conducted a diligent search for the leak.. Dyes, guessing, and throwing parts will not meet with much success.. Get one of those leak detectors and then PM me and I'll explain how to use it.

Re: can not locate ac freon leak.
 

I have a fieldpiece detetor,,, I use it some things, it is nice, but it only work when you can reach places.


I should have replaced the evap when i did the entire system,,, What was driving me nuts was the fact it could hold nitrogen forever and not loose any PSI. My guess is the change in temp was enought to open the void and let the gas leak out???

When i did the converson,, i even isolated the evap and charged with nitrogen,, it did not leak.

Leason learned,

CHris

Re: can not locate ac freon leak.
 

Nitrogen is not for testing for leaks.. It's used to purge the system of old freon and other gases, prior to pulling the vacuum.

BTW, check your PMs.

Re: can not locate ac freon leak.
 

I get what you are saying,,,, I use nitrogen to to purge/braze but also to isolate and test for leaks.

I tested this system and isolated part and still it never lost PSI. I posted here in the event it might help other not chase ghost in the future..


I specifically isolated the accumulator and evaporator and tested to 200 PSI and it never dropped. Anyhoo,,, no sniffer or bubbles are going to get inside the firewall suitcase. That is why the pressure/leak down test.

Thanks for all the help.
Chris

Re: can not locate ac freon leak.
 

Thanks for your in-depth history of this issue.

Some issues like this one are not always the normal procedure.

I was taught the A/C stuff on the early 70's Cadillac's when I was just a Teenager.

Again Thanks for sharing your Knowledge/Experience. :metal:

Re: can not locate ac freon leak.
 

Ugggggh,,,,,,,,,

Again,, freon gone... June 8th,,, all is good,, the unit has been flawless for ~2 months. I just returned from Eastern Idaho on 7/24 and the ac was so cold on low the kids are asking me to turn it down.

7/26, start the truck and the unit is short cycling. and i lost ~a pound of gas in 2 days? I added freon as i needed the truck and it is 100 degrees.


I see no dye/oil anywhere. This is driving me nuts........ Maybe it is the new sanden compressor and leaking at the shaft but i would think i would see a trace of dye?

Re: can not locate ac freon leak.
 

If dye doesnt help there are always detectors - https://www.amazon.com/freon-leak-de...+leak+detector

Re: can not locate ac freon leak.
 

Your story sounds like mine, I have been putting together an aftermarket AC system for my 79 truck and it keeps leaking out. The only part that was not new is the evaporator that had a special thin plastic case that fits under the dash. I have used dye and the meter to find the leak with no luck so I finally came to the conclusion that it has to be the evaporator. The bad news is the evaporator was from the 70's-80's and is no longer made. I found one similar but this is going to get interesting trying to make it work in the plastic evap case.
Once I start a project I usually have to complete it or it bugs me. I only drive my truck to the junkyard and back, after a long hot day of pulling parts it is nice to get into some AC to cool down.
Anyway good luck on your quest for cold AC

Re: can not locate ac freon leak.
 

I wanted share my a/c problem on my 78 retrofit LS1. I pressure tested my system all good. Drive for about a month and no freon. Pressure test, all good. Then Freon would leak out after driving while. Put dye in system no leaks sitting in driveway, drive awhile, empty . Found dye around the ac compressor connection. Replaced o ring recharged same problem. Took it a great mechanic. He called me asked who made the new hoses on my retrofit. I said I did. Here what he told me.
Believe it or not.
I made a hose that went from the dryer to the compressor. Made it as short as I could (about 12 inches) LOL. Looked good, in a straight line fender side to fender sider side. He said when I drove the truck the engine would flex and when it flexed it would move enough to cause a leak at the compressor fitting.(basicly the hose restricted the engine from flexing and put a great deal of pressure on the hose, the hose was holding the engine from flexing.) He made me a new hose that was longer with a small loop and haven't had a problem since. Hope this may help someone.

Re: can not locate ac freon leak.
 

SOrry i did not see this post,,

I thought i had mine solved, andddddddddddd all freon gone again.

I understand about the hose and I allowed for engine movement with sweeping curves in the hose.. I ordered a 77 piece leak test fitting kit and i will isolate one by one.


I do a few of these and never an issue but this is a real PIA. Everything is new, everything test and there is no visual on dye/oil anywhere.

I will report back.... I am going to focus on the compressor,, I think it is a seal even though i see no dye..

Chris

Re: can not locate ac freon leak.
 

Easy enough today or this is a new leak???

The hose from sanden to condenser is leaking at the fitting. as in the tube to the crimping area. Not the o'ring, not the hose (no leak at the crimp but it could be and forcing it out the aluminum tub end of the fitting)

anyway,, it is a #8 fitting and hose. Not sure why this one fitting/crimp failed but I will try again..

Chris

134a capacity
 

Okay,, 9th times a charm.

Crimed a new hose. I use the master cool kit and normally bottom it out as the mark they give is know to not be enough and will leak.


Thought i would post how much freon and temps for any future readers;

~42 ounces
Low side= 26 psi
High side= ~240

vent temp ~45
suction line temp =~52