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Conversion R12 to 134a

dan87951 on Thu June 17, 2010 9:46 AM User is offline

Year: 1987
Make: Porsche
Model: 928
Engine Size: 5.0L V8
Refrigerant Type: 134a
Ambient Temp: ?
Pressure Low: ?
Pressure High: ?
Country of Origin: United States

I have a few questions regarding switching over my R12 car to R134a. I have read a lot of the articles on here and I appreciate the knowledge I have learned from them! Thanks.

I have a 1987 Porsche 928 S4 that I’m restoring, the previous owner switched the car over to R134a a few years ago and it worked ok (was never cold just cool) up until last year when the compressor started getting noisy. I went ahead and disconnected the compressor belt to prevent a catastrophic failure before the compressor locked up. I’m pretty sure the previous owner never flushed the system out before the switch to 134a judging by the poor cooling performance. If I understand what I have been reading the only way to make sure you have a “clean sytem” is to remove all the parts and flush them. I plan on using mineral spirits and safe flush ac with added help from my air compressor to get these components clean. Will this work? So far the new parts I have ordered are as follows:

1.Rebuilt AC Compressor (what oil should I use? I plan on running 134a)
2.New Receiver Drier
3.New Expansion Valve
4.New O- Ring kit

I can’t seem to locate the “orifice” on my car. Do all cars with AC have them? Also the two barrier hoses (im guessing low side/ high side?) that connect to the compressor are original and very old and are no longer available. Is there anyway to get these hoses made? I have no idea of the diameter though. Appreciate all the help. This is a wonderful site wish I would have found it sooner.


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Enthusiast of older German cars

TRB on Thu June 17, 2010 11:06 AM User is offlineView users profile

BVA Auto 100 Ester Glow is a great conversion oil. If you have an expansion valve you will not have an OT.

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JACK ADAMS on Thu June 17, 2010 11:14 AM User is offline

Well sounds like you are on the right track. Flushing the system of all the old oil and any debris that the old compressor may have been tossing would be the first steps that you will need to take. You will need to use a Pag oil or the BVA Oil. You will not have an orifice tube since it is equipped with a expansion valve device.

dan87951 on Thu June 17, 2010 12:14 PM User is offline

Thanks for the info. I guess that solves the orffice tube issue. lol

There are two metal lines that connect to the expansion valve do you recommend I flush these with mineral spirits and safe flush ac or do these lead to some where inside the compartment?

Can ackits rebuild my old AC lines that connect to the compressor?

One last question do I have to put anything on the hose connector threads to make it seal properly? I noticed "RT201B - Nylog (Blue) Gasket Thread Sealant for HFC Systems Price: $9.49" in the online store.

Thanks


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Enthusiast of older German cars

JACK ADAMS on Thu June 17, 2010 12:21 PM User is offline

Yes we can rebuild your hoses if you wish to send them into us. We can get them done in a day turnaround time. Flushing through the TXV is not recommended, best to remove and then flush. RT201B is what we use in our shop as well and works great.

dan87951 on Thu June 17, 2010 12:32 PM User is offline

Jack,

Thanks for the quick reply! What does TXV stand for?

Have any idea on what rebuilding the hoses will cost?

Thanks

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Enthusiast of older German cars

mk378 on Thu June 17, 2010 12:35 PM User is offline

Thermostatic eXpansion Valve. You have a block type TXV-- remove the valve and the two lines that go through the firewall are the ends of the evaporator. With the TXV removed, evaporator can be flushed in place.

dan87951 on Mon June 21, 2010 12:25 PM User is offline

Jack,
I sent you a email with the picture of the lines that need rebuilt. Let me know if you can do it and estimated cost.

Thanks

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Enthusiast of older German cars

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