found the leak in my AC system

[shogun]

Just for info:
the pressure sensor attached to the dryer was the culprit. It leaked between the threaded part and the electric part, where they are crimped together.
Here some pics of the 'jelly droppings'.
Also changed from R12 to R134a on this occassion
http://www.bimmerboard.com/forums/posts/376694

[Dr. evil]

when you changed the refigerants did you have to change out the dryer???

[Guapo]

I recently completely refurbished my AC system. I found 3 leaks -

Low pressure side schrader valve
expansion bock
Compressor shaft seal

I wound up getting a remanned compressor, new expansion block, new valves, new o-rings, and a new drier. Completely flushed the system with mineral spirits, and installed ester oil. Vacuumed the system for a solid hour, then installed R134.

In case anyone is worried about the efficiency of R134 in an E34 designed for R12, I am currently seeing temps as low as 35F in 90F ambient temps.

[shogun]

when you changed the refigerants did you have to change out the dryer???

Yes, I did that. Different oil is used.
"The older mineral oil used in combination with an R12 system will not mix with R134a coolant and will get into the dryer blocking the system. This can cause servere damage to the compressor. So be sure to get as much of the old oil out as posible. You can unbolt the compressor and pour out the old oil or have a shop flush the system with R12 to remove the old oil. "

That is an excerpt from the instructions from Johan here
http://bmwe32.masscom.net/johan/airc...con_R134a.html

A new dryer you can get for less than 50$ for example from www.autohausaz.com
The compressor in my car was changed in 1994 once, so no problem with incombatibility to R134a. See details in the link.

[Dr. evil]

thax shogun

YOUR THE BEST!!

[632 Regal]

<EPA certified and your dead nuts on about the oils.

Yes, I did that. Different oil is used.
"The older mineral oil used in combination with an R12 system will not mix with R134a coolant and will get into the dryer blocking the system. This can cause servere damage to the compressor. So be sure to get as much of the old oil out as posible. You can unbolt the compressor and pour out the old oil or have a shop flush the system with R12 to remove the old oil. "

That is an excerpt from the instructions from Johan here
http://bmwe32.masscom.net/johan/airc...con_R134a.html

A new dryer you can get for less than 50$ for example from www.autohausaz.com
The compressor in my car was changed in 1994 once, so no problem with incombatibility to R134a. See details in the link.

[Guapo]

I used something similar to this to flush out all the old oil:

http://www.ntxtools.com/network-tool...-Retrofit.html

Fill 2/3 with mineral spirits, then charge with compressed air. Once you finally get clear fluid, you can blow clean with compressed air.