Location of expansion valve for the A/C

[jade]

Hi

Has anyone changed the expansion valve ? I am fitting a new compressor and flushing the system, new drier & O rings ect

Need to know the Location of expansion valve for the A/C Think it should be located at the bulkhead where the pipes go through any info or advice appreciated

Thanks

[johne]

It's not at the bulkhead, it's just a bit before. If you follow the high pressure line from the back of the radiator on it's way to the bulkhead it drops down and is held to the chassis at this point with a clip. Also here there is a union in the metal pipe. The expansion valve is inside this union pushed inside in the direction of the bulkhead.

John

[jade]

It's not at the bulkhead, it's just a bit before. If you follow the high pressure line from the back of the radiator on it's way to the bulkhead it drops down and is held to the chassis at this point with a clip. Also here there is a union in the metal pipe. The expansion valve is inside this union pushed inside in the direction of the bulkhead.

John

Thanks !!!

W

[jade]

It's not at the bulkhead, it's just a bit before. If you follow the high pressure line from the back of the radiator on it's way to the bulkhead it drops down and is held to the chassis at this point with a clip. Also here there is a union in the metal pipe. The expansion valve is inside this union pushed inside in the direction of the bulkhead.

John

I have checked this out, where you mean is where the rubber hose join to alloy tube This is a swagged fitting on mine and can not be separated

Thanks

[johne]

I have checked this out, where you mean is where the rubber hose join to alloy tube This is a swagged fitting on mine and can not be separated

Thanks

No, it's nearer to the bulkhead than that. In the attached picture the union in the pipe is dead centre directly above the driveshaft. The expansion valve is in the tube to the left of that union.

John

[jade]

Unfortunately mine does not seem to have a join there, pipe seems to go straight through like the old type, 12a gas. Mine is the newer version so not Shaw what's up with that any ideas it a rs2 8th 94

Thanks

No, it's nearer to the bulkhead than that. In the attached picture the union in the pipe is dead centre directly above the driveshaft. The expansion valve is in the tube to the left of that union.

John

[johne]

If it's not there I don't know what to suggest unless it's inside the bulkhead connection. The expansion valve has to be in the high pressure line ahead of the evaporator inside the car and after the condensor radiator up front: that only leaves about 60cm of tube for it to be in.

It's not vital to change the expansion valve: the reason for changing it is that it has a very small orifice in it which can easily get clogged with crud hence the recomendation to change it when you do an A/C system rebuild & cleanout.

John

[jade]

If it's not there I don't know what to suggest unless it's inside the bulkhead connection. The expansion valve has to be in the high pressure line ahead of the evaporator inside the car and after the condensor radiator up front: that only leaves about 60cm of tube for it to be in.

It's not vital to change the expansion valve: the reason for changing it is that it has a very small orifice in it which can easily get clogged with crud hence the recomendation to change it when you do an A/C system rebuild & cleanout.

John

Thanks John for your help, I have read the audi ac manual It states the they normally have a 2 piece hose with the 13a gas and a one piece hose with the 12a gas even though mine 13a it appears to have a one piece hose so I will look at the bulkhead for it

Cheers

W

[jade]

If it's not there I don't know what to suggest unless it's inside the bulkhead connection. The expansion valve has to be in the high pressure line ahead of the evaporator inside the car and after the condensor radiator up front: that only leaves about 60cm of tube for it to be in.

It's not vital to change the expansion valve: the reason for changing it is that it has a very small orifice in it which can easily get clogged with crud hence the recomendation to change it when you do an A/C system rebuild & cleanout.

John

Dismantled the whole A/c system The valve is not at the bulkhead so it can only be pressed in to the hose at the join where you have suggested Unfortunately my pipe can not be separated to remove this the expansion valve, so I will need to find a new hose which are unavailable at Audi at the present as I would prefer to change it as I have replaced most of the A/C system

W

[jade]

Dismantled the whole A/c system The valve is not at the bulkhead so it can only be pressed in to the hose at the join where you have suggested Unfortunately my pipe can not be separated to remove this the expansion valve, so I will need to find a new hose which are unavailable at Audi at the present as I would prefer to change it as I have replaced most of the A/C system

W

WRONG The hose is 2 piece the join was just very well hidden

I have undone the joint now but there is Not expansion valve there either

At the bulk head joint, hose to evaporator no valve there either very strange !!!


Had the drier change last year after that the A/C did not work well they must of removed it and not replaced it as it work before

[johne]

Jade, without the expansion valve the system won't work at all so if you were even getting some cold after the drier change that would indicate the expansion valve is still in there! It could be pushed a long way down the pipe towards the bulkhead especially if it's blocked and got the full system pressure pushing it along so I'd have a good look at the pipe between your newly found union and the bulkhead connector and make certain it's completely clear - push a tie wrap, length of soft wire etc. through it to check the expansion valve isn't in there somewhere.

John

[jade]

Jade, without the expansion valve the system won't work at all so if you were even getting some cold after the drier change that would indicate the expansion valve is still in there! It could be pushed a long way down the pipe towards the bulkhead especially if it's blocked and got the full system pressure pushing it along so I'd have a good look at the pipe between your newly found union and the bulkhead connector and make certain it's completely clear - push a tie wrap, length of soft wire etc. through it to check the expansion valve isn't in there somewhere.

John

John there is no expansion valve in the system I have removed all the pipes and flushed them

The pipe between the condenser and evaporator on my car appears to be different its a Audi hose looks original The joint I found is under the steering rack not by the drive shaft as in you picture And there is no way the new expansion valve will fit as it has a 40 deg bend just before the joint

The only place the new expansion valve will fit is at the evaporator it slots into the evaporator with no problem but the filter end that slides into the pipe will not work as the expansion valve is 10mm and the inner diameter on my pipe is only 8mm This is all a bit confusing as it looks like Audi have used a different pipe with the expansion valve at the bulkhead rather than at the joint by the drive shaft but I do not have the old expansion to see where or how it was fitted so I am still a little unsure

Thanks

W

[jade]

Jade, without the expansion valve the system won't work at all so if you were even getting some cold after the drier change that would indicate the expansion valve is still in there! It could be pushed a long way down the pipe towards the bulkhead especially if it's blocked and got the full system pressure pushing it along so I'd have a good look at the pipe between your newly found union and the bulkhead connector and make certain it's completely clear - push a tie wrap, length of soft wire etc. through it to check the expansion valve isn't in there somewhere.

John

Ok John Thanks for your advise it been helpful

I had flush the evaporator without to much problem, but after your last post I looked at it again and found the valve it had been forced into the evaporator about 3inch down half way round the bend, I used a 6inch long 3mm wood self tapper screw, screwed it into the top of the valve and with a lot of pulling got it out ! so things make sense now

Its just not fitted where it should be as described by Audi

Also if anyone is interested my replacement compressor is from a VW passat 1.9D mark valero, It has a speed sensor which has be removed otherwise the same

Thanks

W