A/C loses its charge, can’t find the leak

TJScott

TJScott

TJ Enthusiast
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Feb 4, 2017
Messages
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Location
Waterloo, ON Canada
I wrote a few months ago trying to figure out the trouble with my A/C. It turned out to be empty after being great for the last three years I’ve owned it. I took it to my mechanic and he recharged it and added dye. I went back the following week and he checked for leaks and found none. Fast forward 5 weeks (I didn’t use it for about a month) and I went to use it yesterday and again it was acting empty. I took it back last night and same issue. We looked everywhere for the leak, including behind the glove box and under the dash. Just can’t find anything. He said it’s holding a vacuum very well and that a leaking system normally won’t, something like that. It is recharged again with more dye. Has anyone had an issue with a tough to find leak. If so, where did it end up being? I want to help him find this so we can resolve the issue. I’ll happily pay to have it repaired, we just don’t know what to repair. Thank you. 2003 Sport, 4.0, manual


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What does holding a vacuum very well mean?

How many microns did he vacuum to and how long did it hold that for?

AC leaks can be very small, where it takes weeks or months to leak down. This will not be apparent in a quick vacuum check. And possibly not apparent without a very detailed dye check. And if the leak is behind the dash, you won't see the dye.

As an example, the leak detector i have claims sensitivity better than 0.1 oz/yr.

AC leaks can be quite the headache.
 
I have the same problem. Been to 2 different AC shops and they can't find the leak. Mine will blow cold for 3 weeks after a charge, then it'll blow warm. I'm taking mine to a 3rd and final shop Monday for one more try to find the leak. This shop has a new Robinair machine and the dye you inject into the system. If this shop still can't find the leak, I'll be pretty confident the leak is coming from the evaporator in the HVAC under the dash. This will mean removal of the dash to get to it.
 
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superduty said:
What does holding a vacuum very well mean?

How many microns did he vacuum to and how long did it hold that for?

AC leaks can be very small, where it takes weeks or months to leak down. This will not be apparent in a quick vacuum check. And possibly not apparent without a very detailed dye check. And if the leak is behind the dash, you won't see the dye.

As an example, the leak detector i have claims sensitivity better than 0.1 oz/yr.

AC leaks can be quite the headache.
Click to expand...

I’m afraid that vacuum part of the conversation was beyond what I know about the system. My knowledge boils down to, if it can’t hold vacuum, there’s a leak. I was really hoping he would find the leak. Just not to be yet. Maybe next round of checks.


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Just had my AC charged yesterday with dye. No leak detected by the machine either. Hoping mine will hold the charge, but I too am skeptical. So looks like we may all be in the same boat. Will report back if it does in fact lose its charge.


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It could be the evaporator core. The only part of that you can see are the tubes coming out of the firewall. The core is in the HVAC box with the heater core. I would think with as many times as you've had dye put in it, if the evap core is leaking, there would be some I the HVAC box. If so, there may be residue on the drain tube coming out of the firewall also. It's just below the heater core and A/C lines that go into the firewall. I'd look for any sign on dye in/on that tube.


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The drain tube area. Mine just happens to have a piece of hose attached to it so it didn't drain out onto the frame.
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Was it empty when he evacuated it or was there still Freon in it? A charged system can still blow warm if it’s not functioning properly. If the dryer is trashed because it sucked up too much moisture a fully charged system can blow warm. There could also be restrictions in the line that is blocking the Freon from circulating properly to the compressor. I believe there is a orifice tube in one of the lines coming of the dryer, if that is clogged the AC won’t cycle properly and won’t blow cold.
 
We had the same problem a while back & I was talking about my frustration to an HVAC contractor we use all the time for projects at work. He recommend a product made by a company called Cool Air Products; they use it in commercial cooling systems. They use it because it is a polymer free , safe to use with all refrigerants & has no ill effects on AC recovery systems. The auto version of the product name is AC SmartSeal Auto.

We used it after multiple attempt at finding a leak with dye; it has been working for 2+ years without issue on our TJ. Have since used it in an F350 with great results.

Its inexpensive (under $30) but maybe not be the solution for everyone; it has worked for us (twice).... Just another option

http://www.coolairproducts.net/ac-smartseal-auto/
 
Superduty71 said:
We had the same problem a while back & I was talking about my frustration to an HVAC contractor we use all the time for projects at work. He recommend a product made by a company called Cool Air Products; they use it in commercial cooling systems. They use it because it is a polymer free , safe to use with all refrigerants & has no ill effects on AC recovery systems. The auto version of the product name is AC SmartSeal Auto.

We used it after multiple attempt at finding a leak with dye; it has been working for 2+ years without issue on our TJ. Have since used it in an F350 with great results.

Its inexpensive (under $30) but maybe not be the solution for everyone; it has worked for us (twice).... Just another option

http://www.coolairproducts.net/ac-smartseal-auto/
Click to expand...
Thanks, I'm going to check into this. I, too, may have a leak.
 
Will consider this option, if it turns out I have an undetectable leak.

Huge thank you for the suggestion....has me wondering if you work for the co. that makes or markets the product. [emoji6]


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Nope... not affiliated in any way; just lucky enough to have found it & have it work on the two vehicles I used it on. I never even knew the stuff existed till an HVAC contractor we used told me about them (drove around for a year with no AC in the TJ trying to find the leak). The company is much bigger in the commercial (10 - 20 ton units) & residential cooling systems (at supply / distribution houses), which is why I never heard of them prior to him telling me... so just passing along the info.

Besides I'm an idiot... I'm self-employed... :rolleyes:
 
We've had AC recharged by the local auto shop many times over the last several years. All were due to low system charge from leaks. All the leaks were the valves. The shop relates that they are responsible for 90% of the leaks they fix and they replace them as a matter of course. Very prevalent in Chrysler products according to them. All I know is they fix it, they don't leak after that and my AC works as does the AC in all the rigs we've had done.
 
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I had the same issues with my AC it wasn’t blowing cold air and would not hold a charge even though dye was injected into the system it didn’t show a leak that we could find. Installed a brand new factory compressor figuring the seals must have dried out causing a very slow loss of gas and sent me out the door. The cold air lasted about 2 weeks then no Ac, turned out the evaporator had developed a very tiny crack at the junction where one of the lines entered the unit.
 
jeepndogs said:
Was it empty when he evacuated it or was there still Freon in it? A charged system can still blow warm if it’s not functioning properly. If the dryer is trashed because it sucked up too much moisture a fully charged system can blow warm. There could also be restrictions in the line that is blocking the Freon from circulating properly to the compressor. I believe there is a orifice tube in one of the lines coming of the dryer, if that is clogged the AC won’t cycle properly and won’t blow cold.
Click to expand...

He said it was almost completely empty. Once refilled it worked great and blew plenty cold.


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Superduty71 said:
We had the same problem a while back & I was talking about my frustration to an HVAC contractor we use all the time for projects at work. He recommend a product made by a company called Cool Air Products; they use it in commercial cooling systems. They use it because it is a polymer free , safe to use with all refrigerants & has no ill effects on AC recovery systems. The auto version of the product name is AC SmartSeal Auto.

We used it after multiple attempt at finding a leak with dye; it has been working for 2+ years without issue on our TJ. Have since used it in an F350 with great results.

Its inexpensive (under $30) but maybe not be the solution for everyone; it has worked for us (twice).... Just another option

http://www.coolairproducts.net/ac-smartseal-auto/
Click to expand...

I’ll bring this product to his attention for sure.


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mrblaine said:
We've had AC recharged by the local auto shop many times over the last several years. All were due to low system charge from leaks. All the leaks were the valves. The shop relates that they are responsible for 90% of the leaks they fix and they replace them as a matter of course. Very prevalent in Chrysler products according to them. All I know is they fix it, they don't leak after that and my AC works as does the AC in all the rigs we've had done.
Click to expand...

Another worthy mention. Wouldn’t the dye show up there though? It’s cheap, so certainly worth doing regardless.


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mrblaine said:
We've had AC recharged by the local auto shop many times over the last several years. All were due to low system charge from leaks. All the leaks were the valves. The shop relates that they are responsible for 90% of the leaks they fix and they replace them as a matter of course.
Click to expand...
That is also a fair amount of "slow" leaks in tires.
 
TJScott said:
Another worthy mention. Wouldn’t the dye show up there though? It’s cheap, so certainly worth doing regardless.


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Click to expand...
How do you know the dye is from a leak or from the port it was introduced through? I suspect that is what confuses the guy holding the light.
 
mrblaine said:
How do you know the dye is from a leak or from the port it was introduced through? I suspect that is what confuses the guy holding the light.
Click to expand...

The schrader valve is what I suspected too. So far, 3 days the ac is holding up but I noted the color (see pic) at the entrance port. When I mentioned it to my mechanic the following day, he said it ‘shows’ there because that’s where he introduced the dye. I watched the process and didn’t see anything come out when the hose was removed. So Blaine, you’ve given me reason to replace when and if the freon escapes, and we don’t find anything else.

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