can not locate ac freon leak. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chris989 · 07-21-2024, 06:06 PM

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

72c20customcamper · 07-21-2024, 08:01 PM

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

**jerry moss** · 07-21-2024, 09:25 PM

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.

chris989 · 07-21-2024, 09:33 PM

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??

Dead Parrot · 07-22-2024, 09:41 AM

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.

chris989 · 07-22-2024, 02:05 PM

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?

**hatzie** · 07-22-2024, 08:28 PM

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.

v30crewcab · 07-23-2024, 08:06 PM

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.

chris989 · 07-24-2024, 07:15 PM

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

jjzepplin · 07-25-2024, 04:54 AM

In For results.

chris989 · 07-25-2024, 11:26 AM

Quote:

Originally Posted by jjzepplin

In For results.

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..

**hatzie** · 07-25-2024, 03:12 PM

Quote:

Originally Posted by chris989

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..

Is the filter in the orifice valve full of crud?

What's your low side pressure running?

07-21-2024, 06:06 PM	#1
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 594	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

07-21-2024, 08:01 PM	#2
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 8,728	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 __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.

07-21-2024, 09:25 PM	#3
jerry moss Born Psycho Join Date: Feb 2001 Location: brentwood,cal,usa Posts: 4,942	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. __________________ jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA

07-21-2024, 09:33 PM	#4
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 594	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??

07-22-2024, 09:41 AM	#5
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,616	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.

07-22-2024, 02:05 PM	#6
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 594	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?

07-22-2024, 08:28 PM	#7
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	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. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-23-2024, 08:06 PM	#8
v30crewcab Registered User Join Date: Apr 2012 Location: Chatt Tn Posts: 982	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. __________________ 88 military v30 crewcab shortbed 5.9 cummins, nv4500, 205 86 k30, 89 diesel burb, 76 gmc pathfinder 71 longbed 5.3 4l80 http://67-72chevytrucks.com/vboard/s...d.php?t=522535

07-24-2024, 07:15 PM	#9
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 594	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 Attached Images

07-25-2024, 04:54 AM	#10
jjzepplin Registered User Join Date: Feb 2012 Location: Ruskin Florida Posts: 4,566	Re: can not locate ac freon leak. In For results. __________________ 70 swb 4x4 406sbc 700r4 203/205 d60/14blt locker yadda yadda http://67-72chevytrucks.com/vboard/s...88#post6935688 Yeller 72 Blazer 2wd conversion project "No Daggum Money" http://67-72chevytrucks.com/vboard/s...d.php?t=550804 LS1-T56 3.73 LSD super budget build Blanco-2014 Sierra SWB https://67-72chevytrucks.com/vboard/...d.php?t=810350



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