A/C problem

If the big line going to the cab is not cold, then you don't have enough
refrigerant in your system. I do not have a good source of theory handy,
but my basic air conditioning service manual says over and over again, that
R-134a systems cannot be charged by the pressure method. "The only way" is
to evacuate the system and then charge to the proper weight of refrigerant.
I didn't get anywhere with my old Suburban until I started believing the
authors of this book. Now, the AC has been working for two years without
fail. (The new O-rings, compressor, hoses and orifice didn't hurt.)

You can charge refrigerant until the return line (the big one) from the cab
is cold, and your system will work for a while, but it won't be right. You
will either have too much or too little refrigerant in there, and combined
with your leak this is going to mean a system that only works for a couple
of months, if that. When your system is evacuated (which will happen soon,
one way or the other) I recommend replacing all the O-rings and any hose
that is wet with refrigeration oil.

Earle

"MPClark" > wrote in message
...
>
> Alright, I went back to check all of that. After letting the engine and
> A/C run for several minutes, I checked the pressure to be just about
> 40. Then I felt the lines: the two going into the cab are slightly
> warm, the one going into the compressor is also slightly warm, and the
> line coming out of the compressor is too hot to touch. It's confusing
> me because whether there is a leak or not, the pressure is where is
> should be, so low pressure shouldn't be a problem I would think.
>
>
> --
> MPClark

ok you guys
here goes,,, the line going from the accumulator to the evaporator should not
be cold. It will probably be warm because it is liquid refrigerant under
high pressure. The line coming back to the compressor should be colder than
the other line.
Two lines going into the cab. One warmer than the other, and....the one
returning to the compressor should be the colder of the two.
I'll have to check your 134 theory, but it's probably a mixed refrigerant,
and if thats the case, it needs to be dumped and recharged as a whole because
it is more than 1 refrigerant combined together, and they will leak at
different rates. Thats why it must be dumped and recharged as a whole. I
just can't remember the make up of 134a and whether this is a mixed gas or
not without looking at the jug....



Earle Horton wrote:
>If the big line going to the cab is not cold, then you don't have enough
>refrigerant in your system. I do not have a good source of theory handy,
>but my basic air conditioning service manual says over and over again, that
>R-134a systems cannot be charged by the pressure method. "The only way" is
>to evacuate the system and then charge to the proper weight of refrigerant.
>I didn't get anywhere with my old Suburban until I started believing the
>authors of this book. Now, the AC has been working for two years without
>fail. (The new O-rings, compressor, hoses and orifice didn't hurt.)
>
>You can charge refrigerant until the return line (the big one) from the cab
>is cold, and your system will work for a while, but it won't be right. You
>will either have too much or too little refrigerant in there, and combined
>with your leak this is going to mean a system that only works for a couple
>of months, if that. When your system is evacuated (which will happen soon,
>one way or the other) I recommend replacing all the O-rings and any hose
>that is wet with refrigeration oil.
>
>Earle
>
>> Alright, I went back to check all of that. After letting the engine and
>> A/C run for several minutes, I checked the pressure to be just about
>[quoted text clipped - 3 lines]
>> me because whether there is a leak or not, the pressure is where is
>> should be, so low pressure shouldn't be a problem I would think.


--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200506/1

and you can charge off of pressure........here's how
look at the pressure on your gauge on the low side. Look at the
corresponding temp referring to 134a on the gauge. The temperature of the
line RETURNING to the compressor should be 8-16 degrees F higher than the
temp reading on the gauge. This is known as SUPERHEAT. Some will tell you
to take the air discharge temperature, but is a completely inaccurate way of
obtaining the superheat. Too many variables to screw up the temp. Not
enough air flow, etc.....the list goes on. Take the line temp. BUT caution.
If the temp of the line matches or is lower than the temp on the gauge, then
you will be getting liquid refrigerant back to the compressor.
This will have the equivilent effect on the compressor as putting a garden
hose down your carb and turning on the water.
the units are made to pump vapor and not liquid. BAD things happen to
pistons and valves when liquid comes back, so make sure the temp is higher
than what is on the gauge.......

Robb S wrote:
>ok you guys
>here goes,,, the line going from the accumulator to the evaporator should not
>be cold. It will probably be warm because it is liquid refrigerant under
>high pressure. The line coming back to the compressor should be colder than
>the other line.
>Two lines going into the cab. One warmer than the other, and....the one
>returning to the compressor should be the colder of the two.
>I'll have to check your 134 theory, but it's probably a mixed refrigerant,
>and if thats the case, it needs to be dumped and recharged as a whole because
>it is more than 1 refrigerant combined together, and they will leak at
>different rates. Thats why it must be dumped and recharged as a whole. I
>just can't remember the make up of 134a and whether this is a mixed gas or
>not without looking at the jug....
>
>>If the big line going to the cab is not cold, then you don't have enough
>>refrigerant in your system. I do not have a good source of theory handy,
>[quoted text clipped - 20 lines]
>>> me because whether there is a leak or not, the pressure is where is
>>> should be, so low pressure shouldn't be a problem I would think.


--
Message posted via http://www.carkb.com

also, if the corresponding temperature on the pressure temp gauge is more
than 20 degrees F lower than the large line returning to the compressor, I'd
say your low on gas. The lower the superheat # the more efficient the system
is. As the temperature difference gets greater, that means less efficiency,
thus low on charge situation.........use the gauge and the temps, you won't
go wrong.........
let me know how it all turns out..


Robb S wrote:
>and you can charge off of pressure........here's how
>look at the pressure on your gauge on the low side. Look at the
>corresponding temp referring to 134a on the gauge. The temperature of the
>line RETURNING to the compressor should be 8-16 degrees F higher than the
>temp reading on the gauge. This is known as SUPERHEAT. Some will tell you
>to take the air discharge temperature, but is a completely inaccurate way of
>obtaining the superheat. Too many variables to screw up the temp. Not
>enough air flow, etc.....the list goes on. Take the line temp. BUT caution.
>If the temp of the line matches or is lower than the temp on the gauge, then
>you will be getting liquid refrigerant back to the compressor.
>This will have the equivilent effect on the compressor as putting a garden
>hose down your carb and turning on the water.
>the units are made to pump vapor and not liquid. BAD things happen to
>pistons and valves when liquid comes back, so make sure the temp is higher
>than what is on the gauge.......
>
>>ok you guys
>>here goes,,, the line going from the accumulator to the evaporator should not
>[quoted text clipped - 15 lines]
>>>> me because whether there is a leak or not, the pressure is where is
>>>> should be, so low pressure shouldn't be a problem I would think.


--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200506/1

really !!! my 95 grand marquioes has a working never been touched ac system going on
ten years now

"L.W.(ßill) Hughes III" wrote:

> Except we know all air conditioning systems leak with every
> vibration of the engine, since the early eighties when the manufacturers
> switched to O ring connections: http://www.billhughes.com/OringTool.jpg
> God Bless America, ßill O|||||||O
>
>
> tim bur wrote:
> >
> > it's against the law to knowly charge a leaking a/c system and leave the charge
> > in if the leak is not repaired
> > don't try to use a can with sealer it react to o2 to seal the leak so any o2 in
> > the system and it's sealed off but good requiring coils and hose replacement

Then someone has added to it. look at the O-ring connections and
you see the telltale signs of refrigerant oil.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

tim bur wrote:
>
> really !!! my 95 grand marquioes has a working never been touched ac system going on
> ten years now

hey doug, just a correction for you on the two lines going to the cab. only
one should be cold. The smaller one should be warm, and the larger one going
to the compressor should be cold. If they are both cold, then there is a
serious problem. The system would be under charged as the refrigerant would
be flashing through the liquid line going into the cab making that line cold.
It should have a solid column of liquid refrigerant, and thus be warm. It
doesn't get cold until it reaches the metering device, and the refrigerant
flashes to vapor. Now, the smaller line should be cooler than the line
coming out of the compressor (discharge) line, but it should not be cool or
cold.

DougW wrote:
>MPClark did pass the time by typing:
>> I have a 97 Jeep Cherokee. Now that it's the summer I want to use my air
>> conditioning. However, when I turn on the A/C, no cold air is put out
>[quoted text clipped - 4 lines]
>> relay of somesort that controls the clutch, maybe it is stuck it the
>> defrost position? Any help would be greatly appreciated.
>
>Without actually looking myself it sounds like your slightly low
>on refrigerant. That's normal for a system as old as yours. My 93 ZJ
>required a kick in the arse (3oz) back in 2000 or so and actually
>might need a checkup, hasn't gotten that hot yet.
>
>There are two sensors in the AC system. A low pressure and a high
>pressure. the low one is located on the accumulator bottle, the
>high one on the ac pump output.
>
>Be careful about how you measure pressure, a correct reading depends on
>outside temperature also. My guess is your at the very low edge of
>the scale. Also remember to correctly get the pressure you need
>to have the compressor running. That's done by jumpering the harness
>to the low level switch and settign the AC on max/recirc. Both the hoses
>going into the cab should be cold to the touch. If one is cold and the
>other warm then your low (or very overfilled). Always trust the pressure
>gauge.
>
>If your not familiar with servicing AC systems it might be best to let
>a local shop do the work. Around here it's about 90$ for an AC system
>service.
>
>For those that quote laws.. here is the EPA read
>http://www.epa.gov/ozone/title6/609/recharge.html
>The legality depends on the state (or country) you live in.
>


--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200506/1

sorry to bust your bubble but nothing there clean and dry metal

"L.W.(ßill) Hughes III" wrote:

> Then someone has added to it. look at the O-ring connections and
> you see the telltale signs of refrigerant oil.
> God Bless America, ßill O|||||||O
> http://www.billhughes.com/
>
> tim bur wrote:
> >
> > really !!! my 95 grand marquioes has a working never been touched ac system going on
> > ten years now

You don't mind if I don't believe you.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

tim bur wrote:
>
> sorry to bust your bubble but nothing there clean and dry metal