Re: How often does AC need to be recharged?
 

"Peabody" <waybackNO836SPAM44@yahoo.com> wrote in message
news:53u%f.30983$gE.25849@dukeread06...
> Michael Pardee says...
[snip]
>
> If you're saying they have to evacuate all the old
> refrigerant, and add back the correct amount, rather than
> just adding more in the first place, I wonder if this is
> "regulations" or just the standard repair scam bullshit.
>
> I sure would like to get an explanation, in scientific
> terms, of why you can't just add a little 134a. Do pressure
> gauges not work with 134a? Do they not tell you whether the
> charge is correct?

A can of R-134a contains both refrigerant and lubricating oil, and I have
read that the practice of charging without purging can, over time, result in
significant accumulations of excess oil, giving rise to unusually high
operating pressure and leading to premature seal failure.

Re: How often does AC need to be recharged?
 

"Peabody" <waybackNO836SPAM44@yahoo.com> wrote in message
news:53u%f.30983$gE.25849@dukeread06...
> Michael Pardee says...
[snip]
>
> If you're saying they have to evacuate all the old
> refrigerant, and add back the correct amount, rather than
> just adding more in the first place, I wonder if this is
> "regulations" or just the standard repair scam bullshit.
>
> I sure would like to get an explanation, in scientific
> terms, of why you can't just add a little 134a. Do pressure
> gauges not work with 134a? Do they not tell you whether the
> charge is correct?

A can of R-134a contains both refrigerant and lubricating oil, and I have
read that the practice of charging without purging can, over time, result in
significant accumulations of excess oil, giving rise to unusually high
operating pressure and leading to premature seal failure.

Re: How often does AC need to be recharged?
 

Michael Pardee says...

> I don't know why it is so, but even with plenty of
> experience with R-12 and a guage and thermometer I was
> unable to find the correct charge for my son's Acura. It
> turned out the correct charge was about half the bottle.
> When we were done I could hear liquid drops hitting the
> compressor so I told him to leave it off until he got it
> done right. I didn't want to ruin his compressor.

> We added gas slowly and I watched the pressure and vent
> temperature, but it never was anywhere near correct
> until it was done by weight. I can only guess the lag
> time in the system is very long compared to the half
> minute or so it takes R-12 to stabilize. A friend who
> went into refrigeration before he moved away told me
> that with R-134a the condensor pressure is more critical
> than it is with R-12... that may be why it can't be done
> by ear any more. If the condensor has to stabilize to
> evaluate the state of charge it could take hours to do
> it "by ear." But that's only a guess to explain my
> failure.

Thanks. But I still think we need to find an authoritative
technical explanation.

Re: How often does AC need to be recharged?
 

Michael Pardee says...

> I don't know why it is so, but even with plenty of
> experience with R-12 and a guage and thermometer I was
> unable to find the correct charge for my son's Acura. It
> turned out the correct charge was about half the bottle.
> When we were done I could hear liquid drops hitting the
> compressor so I told him to leave it off until he got it
> done right. I didn't want to ruin his compressor.

> We added gas slowly and I watched the pressure and vent
> temperature, but it never was anywhere near correct
> until it was done by weight. I can only guess the lag
> time in the system is very long compared to the half
> minute or so it takes R-12 to stabilize. A friend who
> went into refrigeration before he moved away told me
> that with R-134a the condensor pressure is more critical
> than it is with R-12... that may be why it can't be done
> by ear any more. If the condensor has to stabilize to
> evaluate the state of charge it could take hours to do
> it "by ear." But that's only a guess to explain my
> failure.

Thanks. But I still think we need to find an authoritative
technical explanation.

Re: How often does AC need to be recharged?
 

"Peabody" <waybackNO836SPAM44@yahoo.com> wrote in message
news:YQP%f.1774$iF3.199@dukeread01...
> Michael Pardee says...
>
<snip>
>
> Thanks. But I still think we need to find an authoritative
> technical explanation.
>
Please let us know what you find. It's always good to know these things.

Mike

Re: How often does AC need to be recharged?
 

"Peabody" <waybackNO836SPAM44@yahoo.com> wrote in message
news:YQP%f.1774$iF3.199@dukeread01...
> Michael Pardee says...
>
<snip>
>
> Thanks. But I still think we need to find an authoritative
> technical explanation.
>
Please let us know what you find. It's always good to know these things.

Mike

Re: How often does AC need to be recharged?
 

> A can of R-134a contains both refrigerant and lubricating oil, and I have
> read that the practice of charging without purging can, over time, result
> in significant accumulations of excess oil, giving rise to unusually high
> operating pressure and leading to premature seal failure.
>

$920 later I just found this out. I had a small leak that only happened when
the unit wasnt used for a week or more. I added oil and a recharge can of
134a and my compressor locked up a month later. Was real cold for a month
though! Mechanic told me the same thing, too much oil and shouldnt be done
by shadetree mechanics wiythout meters.

Re: How often does AC need to be recharged?
 

> A can of R-134a contains both refrigerant and lubricating oil, and I have
> read that the practice of charging without purging can, over time, result
> in significant accumulations of excess oil, giving rise to unusually high
> operating pressure and leading to premature seal failure.
>

$920 later I just found this out. I had a small leak that only happened when
the unit wasnt used for a week or more. I added oil and a recharge can of
134a and my compressor locked up a month later. Was real cold for a month
though! Mechanic told me the same thing, too much oil and shouldnt be done
by shadetree mechanics wiythout meters.

Re: How often does AC need to be recharged?
 

"news.easynews.com" <rm@blahblah.com> wrote in message
news:Pl91g.132516$Rb2.87046@fe05.news.easynews.com ...
>> A can of R-134a contains both refrigerant and lubricating oil, and I have
>> read that the practice of charging without purging can, over time, result
>> in significant accumulations of excess oil, giving rise to unusually high
>> operating pressure and leading to premature seal failure.
>>
>
> $920 later I just found this out. I had a small leak that only happened
> when the unit wasnt used for a week or more. I added oil and a recharge
> can of 134a and my compressor locked up a month later. Was real cold for a
> month though! Mechanic told me the same thing, too much oil and shouldnt
> be done by shadetree mechanics wiythout meters.
>
Ow! That lesson was a dear one! I do know that overcharging any A/C sysem
will cause liquid to overflow the evaporator and "slug" the compressor. Very
bad news.

Mike

Re: How often does AC need to be recharged?
 

"news.easynews.com" <rm@blahblah.com> wrote in message
news:Pl91g.132516$Rb2.87046@fe05.news.easynews.com ...
>> A can of R-134a contains both refrigerant and lubricating oil, and I have
>> read that the practice of charging without purging can, over time, result
>> in significant accumulations of excess oil, giving rise to unusually high
>> operating pressure and leading to premature seal failure.
>>
>
> $920 later I just found this out. I had a small leak that only happened
> when the unit wasnt used for a week or more. I added oil and a recharge
> can of 134a and my compressor locked up a month later. Was real cold for a
> month though! Mechanic told me the same thing, too much oil and shouldnt
> be done by shadetree mechanics wiythout meters.
>
Ow! That lesson was a dear one! I do know that overcharging any A/C sysem
will cause liquid to overflow the evaporator and "slug" the compressor. Very
bad news.

Mike