Leaky A/C

wrote:
>
>Yes, I'm just trying to save a hundred or two by troubleshooting and
>changing aany parts needed before fully evacuating and charging the
>syst.

Propane is fine for testing an R12 system (runs OK too)... try
googling *R290 refrigerant*.

You'll need to make up some sort of adaptor to get from a propane
cylinder to the Schrader valve.

Propane has a somewhat higher vapour pressure than R12 and you can
normally get enough charge into the system (without running the
engine) to get the a/c to operate after a fashion. With the engine
stopped, charge until you reach cylinder pressure (you won't need a
gauge). Preferably through the low side but it won't matter much
either way.

Use a soap solution for leak testing.

--
John H

Kevin wrote:
> ******Reply posted at the bottom*******
>
>
> > wrote in message
> ups.com...
> >
> > Steve wrote:
> > > >>87 Lebaron.
> > > >>
> > > >>Obvious freon blowout under hood but leak not detectable as oily freon
> > > >>is all over the hoses, compressor, hood, etc.
> > > >>
> > > >>Other than fully evacuating and recharging the system including tracer
> > > >>dye to detect the leak, is there a better way to find the leak without
> > > >>spending $200?
> > > >>
> > > >>Can one just put compressed air in the freon inlet and search for a
> > > >>leak?
> > > >>
> > > >>I am sure it needs a part(s).
> > > >>
> > > >>Could be hose or compressor seal?
> > > >>
> > > >>I don't want to pay $200 to find the leak and still have to replace
> > > >>hose or compressor and recharge the freon for anothr $200 plus?
> > > >>
> > > >>Any ideas?
> > > >>
> > > >>Email me above and/or post.
> > > >>
> > > >>Thanks in advance.
> > >
> > >
> > > My advice is that unless you FULLY understand how refrigeration systems
> > > work and are prepared to tackle the needed modifications to convert to
> > > R-134a as well as to find/repair the failed component, you'd be WAY
> > > better off financially just taking it to a reputable A/C shop.
> >
> > "Reputable" is easier said than done.
> > I get that I could have multiple issues here including the difficulty
> > because of the r12 system.
> > I hadn't really considered changing over.
> > It will depend on cost of repair t begin with then possible
> > modification.
> >
> > >Its
> > > pretty easy to flush away $200+ trying "shotgun" parts swaps and
> > > half-assed repairs on AC systems and STILL have hot air blowing at you.
> > >
> > Yes, but I'm just exploring the easier stuff to save 70-85$ / hour.
> > I am considering a can of R-134a with fitting adapter to see if I can
> > find the leak.
> > What will this hurt if there is no leak and it was the popoff valve?
> > I would still need the reason the valve popped or I find a leak and
> > replace the part.
> > I hope it is not a bad compressor seal.
> > If find a leak and replace any parts I'm saving about 2 hundred bucks
> > for starters.
> > If there is no fan/condenser problems all that would need to be done is
> > to evac the system and charge with R12.
> > I will need to investigate the difference in costs OF r12 vs changing
> > the system to an R-134a freon but all this is moot until I find the
> > leak and cause.
> >
> > > If you're serious about learning how to do it right, go to the forums at
> > > www.aircondition.com, start reading, study hard, and don't cut corners.
> >
> > Thanks.
> > Right. I'm not trying to cut corners because I need it to work as
> > reliably as possible.
> > I'm just doing what I can to save a few hundred bucks. If the
> > compressor is bad a mechanic will rape me.
> >
> > > A failed R-12 system being converted to R-134a needs to be flushed,
> > > filled with the correct oil, have a new drier installed, and evacuated
> > > with a good HARD vacuum for several hours at a minimum, in addition to
> > > any failed parts that need to be replaced.
> >
> > I understand.
> > The question is one cost vs the other after I find the original
> > failure.
> > Thanks again.
>
> I understand your attempt to save some money by doing what you can. Here's
> how it goes. You spend maybe 30 bucks for a service port adapter, a can of
> 134a with a refill hose. You add the Freon through the low side port and
> instantly hear it hissing out of the busted hose or blown fitting seal.
> Good. Now you can replace the hose or whatever part is leaking yourself for
> whatever the parts cost. Because you saw all that oil under the hood, it is
> most likely a hose or fitting.. It might be the pop off valve on the
> compressor that released because the high side pressure got too hi. In that
> case you will not hear any leaks when you add Freon. You will then have to
> find out why the pressure got too high. There are several things that could
> cause this. Not enough air flow through the condenser (dirty fins, plastic
> garbage from the road, cooling fan inoperative) or even a restriction
> somewhere in the refrigerant system.

Yes, this is where it get's complicted.

>For instance, the dryer desiccant bag
> can rupture and clog the expansion valve witch would block the flow of
> refrigerant. That would cause the high side pressure to increase above the
> pop off valve setting. Unfortunately you will probably not be able to
> diagnose this yourself.

Right. But will anyone else be able to without fully charging the
system?

>If you find a leaking component go ahead and replace
> it and the dryer (always replace the dryer) yourself.

Ok.

>Then have a shop
> evacuated and recharge the system. At that time you can decide weather or
> not to convert to 134a. If you do, the only difference will be the type of
> refrigerant and oil the shop puts back in. If you decide to go back with
> r12, it will be expensive. Only a licensed tech can purchase r12 and it cost
> up to 200 dollars to refill a system with it.

Yes. I have to discuss this option with whatever technician I wind up
with.

> You can expect the shop to refuse any warranty on the job because you
> diagnosed and repaired the system yourself. They can't be responsible if
> something goes wrong, and plenty could go wrong.

Yup.

>There isn't enough time or
> space here to go into all the details of complete A/C repairs. I spend about
> five weeks with my students getting them to understand all the intricacies
> of A/C work. If all goes well and you replace a busted hose, dryer, and
> service port adapters, then have a shop evacuate and recharge with 134a, you
> can expect to spend as much as a couple of hundred on the parts and another
> couple of hundred on the shops labor.

If that is all it is I can be happy. This chance get's remote when the
dealer quotes 165$ for one hose though.

>Probably not much less than an honest
> shop would charge to diagnose and repair the same scenario, but then you
> would have a warranty.

Yes.

>Of course most shops have a great tendency to
> overkill on A/C work so that they don't take any chances of having to eat a
> come back repair. Most likely, if you just bring it in to a shop and say
> "fix it" you will wind up with a 12 to 15 hundred dollar repair bill.
>
That is why I am not too trusting.
I've been working on my own cars for 35 years. I just never had to do
any a/c work.
I found an a/c tech that says he will leak test it for free. I then can
determine what to do from there after I talk to him about these other
possible issues..

>
> Good luck
>
Thank you.
>
> --
> Kevin Mouton
> Automotive Technology Instructor
> "If women don't find you handsome, they should at least find you handy"
> Red Green

wrote:

> Yes, but I'm just exploring the easier stuff to save 70-85$ / hour.
> I am considering a can of R-134a with fitting adapter to see if I can
> find the leak.
> What will this hurt if there is no leak and it was the popoff valve?
>

It would render the entire charge contaminated and un-recoverable
because you would have mixed refrigrerants without properly evacuating
and flushing the system first. IOW, its illegal.

"Steve" > wrote in message
...
> wrote:
>
> > Yes, but I'm just exploring the easier stuff to save 70-85$ / hour.
> > I am considering a can of R-134a with fitting adapter to see if I can
> > find the leak.
> > What will this hurt if there is no leak and it was the popoff valve?
> >
>
> It would render the entire charge contaminated and un-recoverable
> because you would have mixed refrigrerants without properly evacuating
> and flushing the system first. IOW, its illegal.
>

Only illegal for licensed technicians (last time I checked) and mixed
refrigerants are recoverable.


--
Kevin Mouton
Automotive Technology Instructor
"If women don't find you handsome, they should at least find you handy"
Red Green