southpaw51

I have a 1988 S4 with 74500 miles. Replaced the rear evaporator, expansion valve and rings front to back. Checked flaps, etc. Fully charged the system works perfectly for one month and then goes flat. Sniffer picked up a small leak somewhere near the front evap and connection/valves area.

Here's the question... Is there a way to replace the front AC evaporator without removing the dash? I've researched the topic and know what our forums and the disk show. However, I've also read about many "unique" ways that some owners get their repairs done. Just curious if this type of a repair has any flexibility. Need the AC for summer driving.

Follow up question, when I remove the dash. What types of PM work can I work on while I'm in there. Any constructive suggestions are welcome.

Thanks in advance for your help.

dr bob

Leaks at the fittings and around the expansion valve are much more common than evaporator leaks. Leaking gas gathers in the well under the expansion valve, giving the false impression that there's a leak in the tubing. For this typ of leak, I'f try using the dye and a UV light to find the leak. Use the sniffer to find leaks too, of course. Try a plastic bag wrapped around the expansion valve and fittings, with the probe stuffed into the bag to test. The bag will localize what the sniffer can sniff. Meanwhile, since freon is heavier than sourrounding air at low temps, you can sniff for leaks through the front/center vents to the airbox with the system running but the fans on lowests speed. Turn the car off and any leaking gas will start to accumulate in the bottom of the airbox while it's still under pressure and cold. Remember that the evaporator is under the highest pressure it will see when it's hot-soaking rather than while the system is running.

southpaw51

Great directions for me to test system. Thank you for the reply. Will keep you posted on my progress.

Jim

JP Rodkey

Just adding a little to the good Dr.'s advice: No, you can't replace the evap without removing the dash. These evaps are really rugged compared with most others I've seen and rarely fail, so here's hoping for a different outcome.

largecar379

to further add fire to the flame.....

evaporators are commonly offered for cheap (I bought two for less than $50---the whole HVAC box in both cases).

R & R is 10 hours by the book.


--Russ

southpaw51

Removed the console. Pressurized the system. Found the leak at a valve using Dr. Bob's method of isolating the evaporator. Awesome instructions and guidance. The fix is within my reach.

dr bob

Glad it worked for you!