vtraudt

The A/C isn't working, so I wanted to first check the pressure in the system (plug in the gauge/connector of one of those Autozone fill kits I still have around).

Couldn't find the low (or high for that matter) pressure nipple to connect. Can it be that they didn't put them in on the old model? My 98 1.8T AEB has them.

Or am I blind?

duanevw

High side is on the front of the Condenser there is no low side. My mechanic uses a adapter on the back of the compressor to fill mine as its a special low port. Any AC shop can fill it through the high side usually. My Evap. Is leaking though which is common on early audi's even at low miles

Jose'sB5

there's no low port on the 96 A4(AFC) system. it was design so an audi mechanic services it.

vtraudt

How do "audi mechanics" charge the system?
Open the lines at the compressor (or other location), make an adapter (they use machines to charge the systems) to connect machine to the system?

How do 'HVAC shops' do it?

Luxus Panzer

are we sure there is not a port on the cabin side of the firewall??

So much knowledge lost in the "change over" but I remember something about a hidden port on the cabin side.

SAudi3000

well if it helps i found this out several years ago, get the mastercool 82272 adapter online for around 10 bucks and bridge the gap in that sensor and there you go you can refll the a/c at your will.

turbo510

That's it, and available through NAPA. Unscrew the low-pressure switch (on larger aluminum tube, next to cabin air filter) and replace with this adapter. Don't worry about venting refridgerant, there is a valve in the aluminum pipe's fitting. Jumper the low pressure switch connector's two sockets, start the engine and turn on AC, charge with R134a kit as usual. I have one with the integral gauge.

k<@ u d i t e x @ z : 9 0 3>p

Positive there is a Valve? . . Im buying this adapter , is there a tool or kit or is it directly screw on ?

vtraudt

I haven't tried myself, but my local shop actually borrowed it from me when they ran into a old B5 without the valve (1996). Worked like a charm.

But I cannot confirm your specific question: 'is there a valve' (to prevent bleeding the system).

turbo510

Yep, just like a tire valve. Just disconnect the electrical connector, unscrew the pressure switch (17mm wrench I think). You might get a puff of freon when it comes off, but don't worry about it. My only other advice is to roll off the O-ring from the threaded fitting, because it can be damaged by the adapter. Just screw the adaptor in, it doesn't need to be very tight, and then make a jumper to bridge the two contacts of the connector to make the compressor clutch work.