R12 Topping Off

I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12 so
the compressor just cycles on/off. I'm gonna top it off with R12. Is a gauge
necessary or can I just play it "by air". Where can I find the normal
low-side, high-side pressure ranges?

Yes, you're going to need gauges to do it properly. And unless you're a
certified A/C tech, most likely you're not going to be able to get hold of
any R-12..

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from
Home Page: http://www.roberthancock.com/


"Spiderman" > wrote in message
...
> I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12 so
> the compressor just cycles on/off. I'm gonna top it off with R12. Is a
gauge
> necessary or can I just play it "by air". Where can I find the normal
> low-side, high-side pressure ranges?
>
>

Yes, you're going to need gauges to do it properly. And unless you're a
certified A/C tech, most likely you're not going to be able to get hold of
any R-12..

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from
Home Page: http://www.roberthancock.com/


"Spiderman" > wrote in message
...
> I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12 so
> the compressor just cycles on/off. I'm gonna top it off with R12. Is a
gauge
> necessary or can I just play it "by air". Where can I find the normal
> low-side, high-side pressure ranges?
>
>

R-12 is easy to get.


"Robert Hancock" > wrote in message
news:Tfdvc.646141$Ig.552932@pd7tw2no...
> Yes, you're going to need gauges to do it properly. And unless you're a
> certified A/C tech, most likely you're not going to be able to get hold of
> any R-12..
>
> --
> Robert Hancock Saskatoon, SK, Canada
> To email, remove "nospam" from
> Home Page: http://www.roberthancock.com/
>
>
> "Spiderman" > wrote in message
> ...
> > I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12
so
> > the compressor just cycles on/off. I'm gonna top it off with R12. Is a
> gauge
> > necessary or can I just play it "by air". Where can I find the normal
> > low-side, high-side pressure ranges?
> >
> >
>
>

R-12 is easy to get.


"Robert Hancock" > wrote in message
news:Tfdvc.646141$Ig.552932@pd7tw2no...
> Yes, you're going to need gauges to do it properly. And unless you're a
> certified A/C tech, most likely you're not going to be able to get hold of
> any R-12..
>
> --
> Robert Hancock Saskatoon, SK, Canada
> To email, remove "nospam" from
> Home Page: http://www.roberthancock.com/
>
>
> "Spiderman" > wrote in message
> ...
> > I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12
so
> > the compressor just cycles on/off. I'm gonna top it off with R12. Is a
> gauge
> > necessary or can I just play it "by air". Where can I find the normal
> > low-side, high-side pressure ranges?
> >
> >
>
>

Get caught by a local EPA agent:

You'll say dick
is easy to get in federal prison too!


Refinish King


"Spiderman" > wrote in message
...
> R-12 is easy to get.
>
>
> "Robert Hancock" > wrote in message
> news:Tfdvc.646141$Ig.552932@pd7tw2no...
> > Yes, you're going to need gauges to do it properly. And unless you're a
> > certified A/C tech, most likely you're not going to be able to get hold
of
> > any R-12..
> >
> > --
> > Robert Hancock Saskatoon, SK, Canada
> > To email, remove "nospam" from
> > Home Page: http://www.roberthancock.com/
> >
> >
> > "Spiderman" > wrote in message
> > ...
> > > I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on
R12
> so
> > > the compressor just cycles on/off. I'm gonna top it off with R12. Is a
> > gauge
> > > necessary or can I just play it "by air". Where can I find the normal
> > > low-side, high-side pressure ranges?
> > >
> > >
> >
> >
>
>

Get caught by a local EPA agent:

You'll say dick
is easy to get in federal prison too!


Refinish King


"Spiderman" > wrote in message
...
> R-12 is easy to get.
>
>
> "Robert Hancock" > wrote in message
> news:Tfdvc.646141$Ig.552932@pd7tw2no...
> > Yes, you're going to need gauges to do it properly. And unless you're a
> > certified A/C tech, most likely you're not going to be able to get hold
of
> > any R-12..
> >
> > --
> > Robert Hancock Saskatoon, SK, Canada
> > To email, remove "nospam" from
> > Home Page: http://www.roberthancock.com/
> >
> >
> > "Spiderman" > wrote in message
> > ...
> > > I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on
R12
> so
> > > the compressor just cycles on/off. I'm gonna top it off with R12. Is a
> > gauge
> > > necessary or can I just play it "by air". Where can I find the normal
> > > low-side, high-side pressure ranges?
> > >
> > >
> >
> >
>
>

Shop manual goes by condenser inlet temps vs. evap. outlet temps.
If you put a gauge on the low side you'll see at what pressure the low side
cutout comes on. I think it's about 25 lbs. (going on memory, my brother
owns my '89 S Blazer now).
Basically if you charge it enough so the low side cutoff doesn't kick in it
will have enough in it to cool OK. With the motor revs up to 2-3k make sure
the low side doesn't doesn't pull down enough to trip the low side cutoff. I
usually go 10lbs over the cutout pressure with good results. It should be a
warm day when doing it this way, at least over 75 F .
That's how I quickie charge auto systems, 'specially the ones I have no
specs for.
--
John
"anything you say can & will be misquoted & used against you"
'01 FLHR ''Red"
'04 MXZ 600ho
'99 XC700
BRC mem


"Spiderman" > wrote in message
...
> I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12 so
> the compressor just cycles on/off. I'm gonna top it off with R12. Is a
gauge
> necessary or can I just play it "by air". Where can I find the normal
> low-side, high-side pressure ranges?
>
>

Shop manual goes by condenser inlet temps vs. evap. outlet temps.
If you put a gauge on the low side you'll see at what pressure the low side
cutout comes on. I think it's about 25 lbs. (going on memory, my brother
owns my '89 S Blazer now).
Basically if you charge it enough so the low side cutoff doesn't kick in it
will have enough in it to cool OK. With the motor revs up to 2-3k make sure
the low side doesn't doesn't pull down enough to trip the low side cutoff. I
usually go 10lbs over the cutout pressure with good results. It should be a
warm day when doing it this way, at least over 75 F .
That's how I quickie charge auto systems, 'specially the ones I have no
specs for.
--
John
"anything you say can & will be misquoted & used against you"
'01 FLHR ''Red"
'04 MXZ 600ho
'99 XC700
BRC mem


"Spiderman" > wrote in message
...
> I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's low on R12 so
> the compressor just cycles on/off. I'm gonna top it off with R12. Is a
gauge
> necessary or can I just play it "by air". Where can I find the normal
> low-side, high-side pressure ranges?
>
>

"Spiderman" > wrote in message >...

> I have a 1989 Chevy S10 Blazer that blows out warm A/C. It's
> low on R12 so the compressor just cycles on/off. I'm gonna top
> it off with R12. Is a gauge necessary or can I just play it
> "by air".

Try the forums at www.aircondition.com, a place dedicated to car A/C.

People who know better than me are going to hate what I'm about to
say, but if nothing else is wrong with the A/C you can get the R-12
charge about right if you monitor the inlet and outlet pipe
temperatures of the evaporator while the engine runs at fast idle
(must be fast, and run the engine at least 10 minutes before charging)
and you slowly (emphasis on "slowly") put in R-12 until the outlet is
almost as cold as the inlet. Ideally they should be equal, but it's
safer to undercharge than overcharge.

> Where can I find the normal low-side, high-side pressure ranges?

Any car repair manual that covers GM vehicles since they went to
orfice tubes?