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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / July 2005

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Should I add oil to R134a?

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asarangan@myrealbox.com - 17 Jul 2005 18:23 GMT
I flushed the entire system, and installed a brand new compressor. The
Haynes manual says I should pour 2oz of oil each into the evaporator
and condensor before evacuating the system. However, my R134a bottle
says that it has oil already mixed in it. My question is, should I add
this oil, or should I assume that the oil in the refrigirent is enough?
I assume that I still need to pour some oil into the compressor ports
to keep it lubricated during startup.
Steve B. - 17 Jul 2005 19:06 GMT
>I flushed the entire system, and installed a brand new compressor. The
>Haynes manual says I should pour 2oz of oil each into the evaporator
[quoted text clipped - 3 lines]
>I assume that I still need to pour some oil into the compressor ports
>to keep it lubricated during startup.

You also are going to replace the dryer and expansion device aren't
you?

You need to take back the cans with the oil already added and get
regular ol' 134a in a can.  Make sure the compressor manufacturer did
not already put oil in the comrpessor as well.

Find out how much oil your system takes and add the oil back before
you seal the system up.  I do like to spread it across the system like
the book says to avoid slugging the compressor with oil.

Having the proper oil level in the system is critical to compressor
life and system performance.  Make sure you have exactly the right
amount!

           Steve B.
asarangan@yahoo.com - 18 Jul 2005 21:01 GMT
As you suggested I returned the cans and bought regular R134a cans.

Yes I did replace the dryer, but I could not find the expansion device.
This is a 1990 Geo Metro. It does not use an orifice, and I can't find
anything else on the low pressure line. I am guessing that the
expansion valve must be inside the evaporator. The only way to get at
it would be to remove the evaporator, which I am not ready to do. I
measured the exact amount of ester oil, and poured some into the
compressor and some into the condensor. I sealed it up and ran a vacuum
pump for 2 hours. The vacuum stayed at 30"Hg for more than six hours
after the pump was turned off. I am about to recharge the system today.
I will let you know the outcome.

> >I flushed the entire system, and installed a brand new compressor. The
> >Haynes manual says I should pour 2oz of oil each into the evaporator
[quoted text clipped - 20 lines]
>
>             Steve B.
Bruce Chang - 18 Jul 2005 22:17 GMT
> As you suggested I returned the cans and bought regular R134a cans.
>
[quoted text clipped - 8 lines]
> after the pump was turned off. I am about to recharge the system today.
> I will let you know the outcome.

You are a fool if you don't even check the orifice tube/expansion valve
before charging the system.
Comboverfish - 18 Jul 2005 22:43 GMT
> You are a fool if you don't even check the orifice tube/expansion valve
> before charging the system.

So Bruce, how do YOU check the expansion valve when you charge a system
like this?  Better yet, how do YOU check the orifice tube on a receiver
dryer system?

Toyota MDT in MO
Bruce Chang - 18 Jul 2005 23:14 GMT
>> You are a fool if you don't even check the orifice tube/expansion valve
>> before charging the system.
[quoted text clipped - 4 lines]
>
> Toyota MDT in MO

I don't know this system and apparently he doesn't either.  He assumed it
had one and he wasn't going to check it.

In response to your question, I would pull the orifice tube and check to
make sure it has no debris in it at the very least but I'd jsut replace
orifice tube.  It's chump change in comparison to having redo everything
again.

-Bruce
Comboverfish - 19 Jul 2005 12:30 GMT
> I don't know this system...

Your response was rather abrasive considering this fact.

> In response to your question, I would pull the orifice tube and check to
> make sure it has no debris in it at the very least but I'd jsut replace
> orifice tube.  It's chump change in comparison to having redo everything
> again.

That is a good plan if this car had an orifice tube.  It has an
expansion valve, however, which is next to the evaporator.  There was
no direct mention of system contamination.  I see no reason to spend
hours of time replacing or "checking" a part that doesn't need any
attention.  He said he flushed the system -- if done properly, even an
expansion valve can be remotely cleaned by backflushing.

Toyota MDT in MO
Steve B. - 19 Jul 2005 17:15 GMT
>That is a good plan if this car had an orifice tube.  It has an
>expansion valve, however, which is next to the evaporator.  There was
[quoted text clipped - 4 lines]
>
>Toyota MDT in MO

Thanx for pointing out that his car has an expansion valve.

The OP is replacing the compressor so there is at least a good chance
that there is trash in the system. I would replace the valve if I was
doing the job myself if only to preserve the warranty on the
replacement compressor.  I also don't understand how you can do a
decent flush of the evap and lines with the expansion valve still in
place.  How do you manage to get enougt fluid to back feed through the
expansion valve to flush it all out?

                    Steve B.
Comboverfish - 19 Jul 2005 19:07 GMT
> I also don't understand how you can do a
> decent flush of the evap and lines with the expansion valve still in
> place.  How do you manage to get enougt fluid to back feed through the
> expansion valve to flush it all out?

You can't be successful flushing 100% of the time, but experience will
tell you if the cleaning process was or was not a success before
recharging the system.  Every system poses it's own challenges related
to which lines and components need to be removed to facilitate
flushing.  Expansion valves can be cleaned in place if the evaporator
has large enough tubing, or for several hours of extra labor in the
case of most smallish import cars, it can be removed and cleaned or
replaced if too crapped-up.  An example of simplicity would be Chrysler
H blocks -- really easy to get to!

Toyota MDT in MO
Bruce Chang - 19 Jul 2005 17:44 GMT
>> I don't know this system...
>
> Your response was rather abrasive considering this fact.

Sure, I could have candy coated my response but the fact remains that A/C
work is finicky and if you will neglect things because "I'm not ready to do"
then you're gambling.  For me, at least, gambling with A/C work is not worth
it.  It's a lot more time and money than it's worth if it doesn't work out.

>> In response to your question, I would pull the orifice tube and check to
>> make sure it has no debris in it at the very least but I'd jsut replace
[quoted text clipped - 7 lines]
> attention.  He said he flushed the system -- if done properly, even an
> expansion valve can be remotely cleaned by backflushing.

What's involved in checking the expansion valve?  You said it was next to
the evap.  Does it mean the evap core has to be removed to get to it?

-Bruce
Daniel J. Stern - 19 Jul 2005 17:47 GMT
> I could have candy coated my response but the fact remains that A/C work
> is finicky

...and dangerous...

> For me, at least, gambling with A/C work is not worth it.  It's a lot
> more time and money than it's worth if it doesn't work out.

...risk of injury, risk of property damage, risk of death...

> What's involved in checking the expansion valve?

If you have to ask...!
asarangan@yahoo.com - 20 Jul 2005 05:00 GMT
I am the OP. I spent many hours looking for the expansion valve. I
could not find it in the engine compartment. I assumed it had to be
inside the evaporator on the passenger side. Taking that apart is not
an easy job, so I sealed it up and hoped that the flushing would have
taken care of any blockage in the expansion vavle.
Steve B. - 18 Jul 2005 23:22 GMT
>As you suggested I returned the cans and bought regular R134a cans.
>
[quoted text clipped - 8 lines]
>after the pump was turned off. I am about to recharge the system today.
>I will let you know the outcome.

I don't know your car in particular but on many GM cars the orifice
tube is in the high pressure line.  You unscrew the line and slide the
old one out then slide a new one in.

Rebuilt compressors have a long history of less than stellar results
and if you don't replace the orifice tube / expansion device you
instantly void the warranty on the new compressor.  It is worth taking
the time to find it and replace it.

Good luck!  
Steve B.
 
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