aircon prob's help please

[passat tdi130]

hi all i have a prob with my aircon

i had it refilled only to find out a few days later the aircon gas had all gone again...

obviously a leak

i took car back to quikfit for a refund and they told me they would refill it free..!!!
they did so and assured me if there was a leak the machine wouldnt fill the aircon
anyhow the machine filled it and it worked great for a few days
then empty again i looked under car to see if i could see any leaks and the plastic belly panel was covered in an oily fluid from front to back on the drivers side...!!!!!!!!!!

any idea's as to where that might be coming from

thank's in advance



p.s. i may have the air con pipework that runs from the cylinder at the rear of headlight right back but they are from a 99 passat would these fit could anyone tell me

also my car is the 2003 1.9 tdi estate sport

[snapdragon]

Some places always refill with fluorescent dye added and then shine a UV lamp around to check for leaks before releasing the car back to the owner. eg.http://www.eveshamvw.co.uk/aircon.php
is the top UK result with google, and they charge:
Fluorescent Leak Detection Dye £6.90 inc vat
or
Service B (Including free leak detection additive) £85.68 inc vat

You could do with finding someone near you who uses the dye.