Need help finding an AC leak

[b4black]

I'm trying to get the AC working on my truck, 1996 Dodge Ram diesel.

It's been out for a while, and it has 250k miles, so I figure a new accumulator and compressor were in order. Did the condenser too, and changed the o-rings on the all the lines.

I hooked up a set of manifold gauges and a vacuum pump. Pulled a vacuum for a ½ hour. Closed the valves and it held vacuum for ½ hour. So I put in the freon and it worked great for a couple days. Then it quit and the freon was low.

I then shot some UV dye in the system and added another can of freon. Drove around until the AC quit again. I got out the UV flashlight - I can't find a leak anywhere. (They should be pretty obvious, right?)

Best I can tell, the schrader valves are not leaking. They are so cheap, I'm thinking of doing them anyway.

This is my first time doing AC, so it very likely I miss something important. Or that I have no clue what I'm doing. Any advice, besides taking it to a shop?

Thanks!

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[GTvert90]

Trying to fix the AC on my 94 Mustang was so frustrating and expensive with all the Freon. IIRC mine held a vacuum but wouldn't hold pressure. I remember taking apart the tool to pull vacuum to allow it to pressurize the system and it leaked out almost immediately.

 

[GTvert90]

Good luck!

 

[bikrboy128]

being an old dodge it's probably the evaporator core, which means ripping the dash out. do a heater core while you're in there too

hit the UV light where the "ac water" drains, bet the tube will light up green.

 

[nytebyte]

being an old dodge it's probably the evaporator core, which means ripping the dash out. do a heater core while you're in there too

hit the UV light where the "ac water" drains, bet the tube will light up green.

Was thinking the same thing. When you didn't find dye anywhere, my next question was "did you check the exchanger inside the dash".

 

[b4black]

. IIRC mine held a vacuum but wouldn't hold pressure. I remember taking apart the tool to pull vacuum to allow it to pressurize the system and it leaked out almost immediately.

Thanks. I was worried that could be a possibility.

being an old dodge it's probably the evaporator core, which means ripping the dash out. do a heater core while you're in there too

I thought about the evaporator. I checked it before I did anything else (with vacuum). I saw the videos on replacing it. Not worth the effort, IMO.


So, please forgive me, but I'm thinking of using a can of stop leak. I read reviews on amazon and it seems like many people have success using them.

 

[bikrboy128]

Thanks. I was worried that could be a possibility.



I thought about the evaporator. I checked it before I did anything else (with vacuum). I saw the videos on replacing it. Not worth the effort, IMO.


So, please forgive me, but I'm thinking of using a can of stop leak. I read reviews on amazon and it seems like many people have success using them.

some systems will hold vacuum but not pressure.

a can of stop leak probably wont do anything. plus it can clog up other parts of the ac system. if you end up putting that crap in and decide to get ac work done later, make sure to tell the shop. stop leak will ruin their $5k+ ac machine.