Climate Control

R-134a Conversion O-Ring List

I just replaced my A/C O-rings this past weekend (OK, I still have a couple more on order) in the process of converting to R134a and will be having the system leak tested and filled next week.

Here's a list of part numbers, sizes, and quantities of O-rings I found in my car (88 S4 with rear A/C):

part number; size(mm); # front; # rear
==============================
999 707 284 40; 6.6 x 1.5; 0; 2
999 707 247 40; 7.5 x 2; 4; 3
999 707 261 40; 9.0 x 1.8; 2; 0
999 707 250 40; 10.6 x 2; 3; 1
999 707 251 40; 14.0 x 2; 3; 4
999 707 252 40; 17.0 x 2; 2; 0

And here's where they're all located:

Front A/C:

1. expansion valve (under plastic tray next to intensive washer reservoir): 2 x #251, 1 x #250, 1 x #247.

2. return line from expansion valve, middle of firewall: 1 x #252.

3. compressor fittings: 1 x #251, 1 x #250.

4. other side of return line to compressor at low side fill valve: 1 x #252.

5. heading into condenser: 1 x #250.

6. bottom of condenser heading up to receiver/drier: 1 x #247.

7. pressure and temperature switches just before receiver/drier: 2 x #261.

8. at receiver/drier: 2 x #247.


Rear A/C:

1. expansion valve: 2 x #251, 1 x #250, 1 x #247.

2. solenoid valve under passenger seat: 2 x #284.

3. 2 pipes under car from solenoid valve to front connections: 2 x #251. 2 x #247.


Enjoy,
Greg Klanderman