993James993

Greetings Tore,

I thought I would ask here instead of in a PM as this might interest others.

Is it possible to replace the expansion valve and o-rings that are located just behind the firewall, without removing the firewall and fuel tank?

My '95 will not hold freon and shows dye in this area. If possible, I would like to replace the expansion valve and repair this leak as a first step, prior to a more lengthy repair. I previously searched but could not find anyone who has done this.

Thank you,

Jim

IXLR8

Also Tore, if removing an A/C component and no R134a compatible oil is lost, I would assume no oil needs to be added.

Would evacuating the system with a pump remove any of the oil, or does it just remove the R134a freon?

BTW, always impressed with your very informative web site and DIYs.

ToreB

Thanks for the trust both of you, but I have little or no knowledge of the "chemistry" in the cooling systems in our cars. My expertise lies in the electronics, especially in the 964/993.
Judging by this DIY, I would think you will have to remove the fuel tank, air system and fuse box to do anything down there.

To my knowledge, evaporator leaks are far, far more frequent than expansion valve faults. I suppose you'll have to go the long way anyway.

And thank you for the credits Alex! I appreciate it very much.
Cheers,
Tore

IXLR8

I'm still cursing for not coming across your OBD Diagnostic Interface sooner; I finished building the one shown on Rennlist a few months earlier which cost me more and is in a less elegant package. Oh well.

nile13

Tore, a little more info on OBD tool, please? I've read the description on the page. Can it exercise the same things as Hammer?

ToreB

My adapter is made for use with the Scantool software made by a Rennlister. There's several discussion threads here on this topic, but I believe the Porsche Bosch Hammer tool present some more features such as flushing the Carrera 4 ABS system. However, Scantool offer most , if not all functions available in the different OBD-connected electronic units in our cars.
Cheers,
Tore

nile13

Tore, thanks!

it looks like '95s will need the adoptor cable as well? What's the shipping like to US? I'm thinking of one.

BTW, when i downloaded software onto my laptop to see it complained that it's not seeing a COM port and wouldn't run.

ToreB

My 95 C4 has a modern OBD2 connector, so you'll have to find out what type you have. My downloadable software pack includes a troubleshooting guide, that would get things sorted for you. Shipping to the US is NOK 75.-
Please pop me a mail or PM if you have more questions about the T-OBD, we're hijacking Jim's thread on A/C repair here. ;-)
Cheers,
Tore

MarkD

Alex,
Evacuation of an AC system does not remove oil, only removes refrigerant and boils out moisture. Oil is lost when components are replaced, with the majority ending up in the compressor. Adding too much oil to the system will actually decrease efficiency, worst case, lock it up.

Not sure of laws in Canada, but here in the US, it is illegal to vent refrigerant to the atmosphere. It must be captured... And proper licensing is required.




Tore is the man when it comes to the CCU !

Jim,
yes, you can replace the exp valve without removing the firewall. It is tight but can be done... Take care to ensure o-rings are properly seated and all will be well.

993James993

Hi Mark and Tore,

Thank you!!

Mark, that is great news!

I looked at the PET and came up with the following parts list:

Expansion Valve x 1 ea (928-573-123-05)
Pan Head screw M 5x35 x 1ea (000 043 300 11)
O-Ring 10,6 x 2ea (999 707 250 40)
O-Ring 14 x 4ea (999 707 251 40)
O-Ring 7,5 x 2ea (999 707 247 40)

Am I missing anything?

Thanks again,

Jim

MarkD

Jim,

there are 4 o-rings at the exp valve. PET lists them in two different locations
the list you have will probably cover it but I need to check when in my office later to verify part #s

you will want to lubricate the o-rings lightly with mineral oil when installing.
everything else looks good on your list

have fun!

IXLR8

Not necessarily.

Very early 993s had a 19 pin round diagnostic connector.

My 1995 has an OBD II connector (more correctly called a J1962 connector) but my car is OBD I Certified.



Note the "OBD I Certified" on the sticker of my 1995 C2...


Note OBD II was not made mandatory till 1996 for cars sold in the US.

IXLR8

Thanks; what I figured but wasn't 100% sure.

This on my 12 year old Honda daily driver; my 993 is ice cold...in fact, too cold.

The Honda had a slow leak many years ago; every late fall when it got cold, so I suspected an O-ring. I'd top it up a tad and all was well till the next fall. Then I used a dye to try to find the very slow leak with no results. After using the dye, it hadn't leaked for more than 5 years, till this summer.

I now have to vacuum the system, because you can only top up so often.

The factory Honda manual shows measuring the oil poured out of the old compressor and adding the same amount of fresh oil when replacing the compressor.

Even R134a? I wonder why they sell it a auto stores without a permit required?

993James993

Hi Mark,

After searching some more I found this post you made back in 2009:


What is involved in replacing the Receiver/Drier? I found part # 944 573 143 01 in the PET.

Thanks for your help,

Jim

MarkD

oh crap, thanks Jim.... Not awake enough yet when I posted
yes, it is a good idea to replace the receiver/drier when the system is opened.
it is located behind the driver side fender liner. Not hard to get to.
the exp valve will be the fun part of the job