Pressurize A/C to find leaks?

On Sun, 18 May 2008 06:04:10 GMT, "Calab" <[email protected]> wrote:

>I've decided to take one more stab at fixing my A/C in my '93 Mazda 626...
>
>My problem right now is that, even after replacing the blown high pressure
>line, that the system won't hold a vacuum.
>
>What I want to do is apply a bit of pressure to the system and use a soap
>solution to try and identify where the leak is occurring. Sounds straight
>forward, but I'm not sure how much pressure I can safely apply to the low
>pressure fitting.
>
>How much pressure can I apply here? Will this do what I need?
>

You can easily put 50psi in the lines. Low pressure side is around 40
when in operation while high side will be 200 or more. Have you
already replaced the o-rings that you just replaced? Seems most
likely that one of those got nicked or rolled under upon assembly.

If you can't find the leak Second shot would be to put in 1 can of
134a and take it to an a/c shop with a sniffer. They can tell you
pretty quickly what is leaking.

Steve B.

"Steve B." <[email protected]> wrote in message
news:kvb034d4nln5jd6t386817aistrir5b7ju@4ax.com...
> On Sun, 18 May 2008 06:04:10 GMT, "Calab" <[email protected]> wrote:
>
>>I've decided to take one more stab at fixing my A/C in my '93 Mazda 626...
>>
>>My problem right now is that, even after replacing the blown high pressure
>>line, that the system won't hold a vacuum.
>>
>>What I want to do is apply a bit of pressure to the system and use a soap
>>solution to try and identify where the leak is occurring. Sounds straight
>>forward, but I'm not sure how much pressure I can safely apply to the low
>>pressure fitting.
>>
>>How much pressure can I apply here? Will this do what I need?
>>
>
> You can easily put 50psi in the lines. Low pressure side is around 40
> when in operation while high side will be 200 or more. Have you
> already replaced the o-rings that you just replaced? Seems most
> likely that one of those got nicked or rolled under upon assembly.
>
> If you can't find the leak Second shot would be to put in 1 can of
> 134a and take it to an a/c shop with a sniffer. They can tell you
> pretty quickly what is leaking.

Thanks folks! This is what I figured, but wanted to hear a few more opinions
before I broke something.

I'm planning on checking all the joints this time, instead of only the ones
that I needed to loosen to do my repairs.

In article <uFPXj.276321$pM4.134492@pd7urf1no>, "Calab" <[email protected]>
wrote:

> I've decided to take one more stab at fixing my A/C in my '93 Mazda 626...
>
> My problem right now is that, even after replacing the blown high pressure
> line, that the system won't hold a vacuum.
>
> What I want to do is apply a bit of pressure to the system and use a soap
> solution to try and identify where the leak is occurring. Sounds straight
> forward, but I'm not sure how much pressure I can safely apply to the low
> pressure fitting.
>
> How much pressure can I apply here? Will this do what I need?

What do you propose to pressurize with?

>> I've decided to take one more stab at fixing my A/C in my '93 Mazda
>> 626...

>> What I want to do is apply a bit of pressure to the system and use a soap
>> solution to try and identify where the leak is occurring. Sounds straight
>> forward, but I'm not sure how much pressure I can safely apply to the low
>> pressure fitting.
>>
>> How much pressure can I apply here? Will this do what I need?

> What do you propose to pressurize with?

Dried air from an air compressor.

"aarcuda69062" <[email protected]> wrote in message news:nonelson-
> What do you propose to pressurize with?

Air should be okay, assuming that he has lost most of the pressure already
AND
that he repairs and evacuates the system.

Of course, if a small leak is present in some hidden place, evaporator
coil, etc.,
he may never spot it with soap bubbles.

The best way to find tiny leaks is with an electronic sniffer, but not
everybody has
that readily available.

I used to have one of those old torch type leak detectors and it was
worthless
for everything I ever tried it on. Thank goodness there are better tools
out there
today.

HLS wrote:
> I used to have one of those old torch type leak detectors and it was
> worthless
> for everything I ever tried it on. Thank goodness there are better tools
> out there
> today.

I've seen guys who were great with those. Definitely a skill to use, one that
was beyond me too.

--
Barack Obama, May 9: "I've now been in 57 states? I think one left to go."

"clifto" <[email protected]> wrote in message
news:ogi9g5-gns.ln1@remote.clifto.com...
> HLS wrote:
>> I used to have one of those old torch type leak detectors and it was
>> worthless
>> for everything I ever tried it on. Thank goodness there are better tools
>> out there
>> today.
>
> I've seen guys who were great with those. Definitely a skill to use, one
> that
> was beyond me too.

Well, I do have a TIF5000 detector
(http://i20.ebayimg.com/08/i/000/f1/45/d5c1_1.JPG)... but I've had little
chance to get used to operating it. I'll definately try it out once I've
done testing with pressure & soap solution.

In article <venYj.5866$r82.2578@nlpi069.nbdc.sbc.com>, [email protected]
says...
>
> "aarcuda69062" <[email protected]> wrote in message news:nonelson-
> > What do you propose to pressurize with?
>
> Air should be okay, assuming that he has lost most of the pressure already
> AND
> that he repairs and evacuates the system.
>
> Of course, if a small leak is present in some hidden place, evaporator
> coil, etc.,
> he may never spot it with soap bubbles.
>
> The best way to find tiny leaks is with an electronic sniffer, but not
> everybody has
> that readily available.
>
> I used to have one of those old torch type leak detectors and it was
> worthless
> for everything I ever tried it on. Thank goodness there are better tools
> out there
> today.

Yeah those torch type leak detectors were better at turning refrigerent
into nerve gas than finding leaks.
The only person in this thread that I know of and would trust my AC
sytem to is aarcuda. I'm suprised he's been silent about some of the
post here. No offense but I don't think the OP is knowledgeable enough
or equipped well enough to tackle the AC system. There are so many
basics that aren't even being covered here or followed on.

Heatwave wrote:
> In article <venYj.5866$r82.2578@nlpi069.nbdc.sbc.com>, [email protected]
> says...
>> "aarcuda69062" <[email protected]> wrote in message news:nonelson-
>>> What do you propose to pressurize with?
>> Air should be okay, assuming that he has lost most of the pressure already
>> AND
>> that he repairs and evacuates the system.
>>
>> Of course, if a small leak is present in some hidden place, evaporator
>> coil, etc.,
>> he may never spot it with soap bubbles.
>>
>> The best way to find tiny leaks is with an electronic sniffer, but not
>> everybody has
>> that readily available.
>>
>> I used to have one of those old torch type leak detectors and it was
>> worthless
>> for everything I ever tried it on. Thank goodness there are better tools
>> out there
>> today.
>
> Yeah those torch type leak detectors were better at turning refrigerent
> into nerve gas than finding leaks.

What, you don't like the smell of phosgene in the morning? (for the few
milliseconds you can smell it, anyway) :-p

> The only person in this thread that I know of and would trust my AC
> sytem to is aarcuda. I'm suprised he's been silent about some of the
> post here. No offense but I don't think the OP is knowledgeable enough
> or equipped well enough to tackle the AC system. There are so many
> basics that aren't even being covered here or followed on.

That is quite probably true. But its also reasonably harmless to try to
find a large leak with low-pressure air (50 PSI or less). It is
interesting to note that most factory service manuals for R-134a systems
advise against testing with air, because air/R-134a mixtures in just the
right combination and at high enough pressure are apparently combustible.