Why Do R134A Systems Leak So Frequently?

[Msmith68w]

For the 7th year in a row, the air conditioning system in my truck has decided to piss out all it's refrigerant.

Every year I find and fix a new leak (I've replaced literally every component in the whole system now with the exception of the condenser and the lines coming off the compressor), fix the leak, run a vacuum on the system, it holds a vacuum (all leaks fixed), and recharge it...and then next year it leaks again. What gives? Is there something inherent to the designs of these systems of of the refrigerant itself that makes it leak so badly? I've had similar issues with nearly every car I've owned. It seems like keeping refrigerant in an aging car is just **** near impossible.

 

[LazyDog]

How long do you run the vacuum, the longer the better. Also do you replace the drier every time you open the system up???

 

[Msmith68w]

How long do you run the vacuum, the longer the better. Also do you replace the drier every time you open the system up???

Usually a half hour to an hour.

No, it's never totally flat, just low enough to cross the pressure threshold where the compressor won't run. I always catch it fairly early.

 

[Chris142]

I heard that e134a has very small molecules. Don't know how true that is. I also heard that pag oils shrink rubber parts like hoses and orings. When I went to ac classes they really pushed using Ester oils to help prevent leak's. Every system I ever worked on got a couple oz of ester. It did seem to cut back on the small unfindable leak's.

 

[Msmith68w]

I heard that e134a has very small molecules. Don't know how true that is. I also heard that pag oils shrink rubber parts like hoses and orings. When I went to ac classes they really pushed using Ester oils to help prevent leak's. Every system I ever worked on got a couple oz of ester. It did seem to cut back on the small unfindable leak's.

Thanks for the heads up, I'll look into this.

 

[slacktide_bitog]

Small molecules. In fact, they're even smaller than dye molecules, which is why some leaks can't be detected

One thing that could help is to run the AC at least once a week. You can do this even with teh heat on (if you do, air will still blow hot not cold, don't worry). If you have a car with automatic climate control, it will usually run the compressor regardless of temperature setting.

 

[Chris142]

Yes running the system is a must. They leak more when sitting than when running.

Also regarding ester oil. Semi trucks use ester and those compressors last hundreds of thousands of miles. Cars often use the same compressor and with PAG oil do not last nearly as long. As I said the classes really pushed ester oil.

 

[clinebarger]

Depends on the vehicle....

My Silverado & Corolla got @ 10 years out of their factory charges, Silverado's high pressure port decided to leak all the Freon out overnight & the Corolla wasn't performing very well on hot days.

The Avalon has been going strong for a couple summers after a engine replacement which required a re-charge.
The Camaro will still freeze you out at the 6 year mark & it has TIG Welded fittings

What truck are we talking about here??

 

[JHZR2]

My 98 S-10 holds its r-134a charge. The original compressor leaked after about 15 years, but I put a sanden in and no issues. My R-12 systems hood charge for years as well. I run them every time the car operates. I believe that’s the difference and cause...

 

[4WD]

Depends on the vehicle....

My Silverado & Corolla got @ 10 years out of their factory charges, Silverado's high pressure port decided to leak all the Freon out overnight & the Corolla wasn't performing very well on hot days.

The Avalon has been going strong for a couple summers after a engine replacement which required a re-charge.
The Camaro will still freeze you out at the 6 year mark & it has TIG Welded fittings

What truck are we talking about here??

Same … Hit or miss … my 2010 GMC never lost any in the 8 years I had it … our 2014 Ford has been solid to 140k - but our 2015 Ford within 2 years was a leaker - and replaced by 2017 Tahoe that’s solid …

 

[spasm3]

I had to add to my avalanche today. But it sits a lot.
If It loses r134 from sitting, does that mean it loses some oil too?

 

[Jake_J]

I wouldn't really place the blame on R-134a systems, as the old R-12 systems leaked just as much. Cars in general aren't the idea environment for a AC system being exposed to all the vibrations of the road, the heat cycles of the engine bay, all the flexible hoses requiring seals, etc. Household fridges uses R-134a and leaks are very rare, but a fridge has a easy life just sitting in a climate controlled house.

 

[Chris142]

I had to add to my avalanche today. But it sits a lot.
If It loses r134 from sitting, does that mean it loses some oil too?

Generally yes

 

[Chris142]

Found this. Says ester can alter the dimensions of seals. Basically swells them a Little. Helps stop leaks.

 

[HyundaiAbuser]

I heard that e134a has very small molecules. Don't know how true that is. I also heard that pag oils shrink rubber parts like hoses and orings. When I went to ac classes they really pushed using Ester oils to help prevent leak's. Every system I ever worked on got a couple oz of ester. It did seem to cut back on the small unfindable leak's.

This is r134a molecule (left) vs the old r12 (right). It would appear as though r134a is larger per molecule so r12 would probably leak more in the same system, although both are quite small in the grand scheme of things.

 

[JMJNet]

What truck are we talking about?
All my Toyota (Camry and Sienna and HIghlander) shows no problem.
Old Suburban (GM) on the other hand was charged once since the compressor was replaced.
I figured out the leak was from the low pressure port and caused by the threaded cap and it is good.

 

[slacktide_bitog]

View attachment 55653 View attachment 55655

This is r134a molecule (left) vs the old r12 (right). It would appear as though r134a is larger per molecule so r12 would probably leak more in the same system, although both are quite small in the grand scheme of things.

Cl is much bigger than F.

2 Cl and 2 F will be much bigger than 4 F

 

[nthach]

A 2005 Sienna, LS430 and a 1998 Explorer I care for are holding their charge. R-134a has smaller molecules. The OEMs have mitigated that with barrier hoses.

 

[alex_at]

@Chris142: You say ester helps.... what kind of ester additive oil has to be used? Is there an additive that I can add myself or can buy to get to my shop to add it for me?

R1234yf is what I'm using if it helps

 

[Chris142]

@Chris142: You say ester helps.... what kind of ester additive oil has to be used? Is there an additive that I can add myself or can buy to get to my shop to add it for me?

R1234yf is what I'm using if it helps

Any auto parts store will have it. They keep it behind the counter so you have to ask for it.