Alrighty so this is an odd issue, a 1997 audi a4 2.8 quattro is having an odd issue. When im driving it with the A/C OFF its drive fine, but when i turn ON the a/c the battery and brake light turn on, lights start dimming, and i hear squeaking coming from the engine bay and the power steering is gone, when i turn it back on everything goes back to normal and the brake/battery lights go away...any idea as to what the issue is or could be? The car starts fine, and drives fine when the a/c is off, so i doubt its the alternator and the battery is fine. Any ideas? Thanks in advance.

 

that is giving you problems (accessory belt) when you turn the AC on, I would assume your compressor is uber messed up and in dire need of compressor oil

(Audi C5 A6 Quattro 2.7T > Climate Control > Air Conditioning > ES#261761 Air Conditioning Compressor Oil - G052154A2)

It might have been too long & now you need a new compressor.

when you turn the AC on & the issues begin does it affect power & performance (even slightly)? Like something is hindering the belt on its normal rotation? This will be the deciding factor here.

 

I belive it didnt not affect the performance of the car, only the electrical/ps.

 

If you have a short in the AC system it may cause this to happen. Chances are its concerning your AC compressor. Everything that's giving you problems is connected to the accessory belt. Might be worth checking the tensioner & belt for starters.