Ok, I see there are already 2 other threads on the first page with AC issues but mines different.

Driver side blows as cold as I request, Passenger side is hotter then it ever even got with the heat on full. Makes no difference if I use the defroster, half the windshield blows hot, the other side cold.

Car throws no HVAC codes, and is a dual zone unit.

I'm at a loss, because while the dual zone does alter one side to the other, it was never very noticeable before and it was never one side gets heat and the other gets air?

 

Try to reset doors by pulling the 27 fuse - if that doesn't work it may need freon -

 

 

Thanks, I'll try the 27 fuse. But Freon in Half the system? That just doesn't make any sense to me?

 

Its not freon in half the system...its just the way the A/C operates when low for some reason..

 

Cool thanks.

 

Rather than start a new thread, I found this one which matched my issue exactly...

History
I had my car in to the dealer two weeks ago when the column lock disabled my 98 A4. They repeated the recall procedure and fixed the problem. They told me that the original parts that they used for the recall when it locked up two years ago must have gone bad. After picking up the car the AC blew only hot air, everything came on automatically but the air was very hot, not a trace of cool air.

I took it back in to them, and held my tongue as they explained that it would cost me $50 for them to diagnose what the problem with my AC was (despite the fact that it quit working while it was being serviced... how could you prove such a thing...). They told me the compressor was bad, the system had zero pressure, yadda yadda yadda, and for 1500 dollars they woudl fix it all up.

Today
Since it's a convertible I don't use the AC much anyway, and I was still too upset about the situation to think about paying them a penny to fix it. So I picked up a $20 refill kit at Checkers with the attached pressure gauge. Started the car, turned on the AC, and attached the kit... 30 psi

So, I went and sat back inside and what do you know.. the driver side was blowing pretty cold, but the passenger side was blowing hot. Messing with the dual zone control didn't make any difference. I could change zones from defrost, face, foot, and any mixture of the three and each time the driver side was cold and the passenger side was hot. I ended up adding some freon to the system to see if the gauge would move or if it would cause the passenger side to cool off.. but even after emptying the entire can the gauge never moved past 35 psi.

I found a few references to pulling fuse 27 in the footwell to reset the HVACCON (HVAC Controller?) which I did, but this didn't fix the issue. Some have stated that perhaps having too little freon in the system could cause this (doesn't make alot of sense to me but I emptied a large can into it nevertheless).

So far I've only found two threads where this has been reported, I'll keep looking, but if you have any other suggestions of how to get the passenger side to blow cold like the driver side I'm all ears

 

Had poor cooling. Cleaned condenser with NU-BLAST, replaced inline orfice tube ($2.50) evacuated and recharged system with 2 cans of freon (that's all it takes). If you overcharge it will lose cooling efficiency. Still poor cooling. Did vacuum lines 2 years ago eaten by battery acid. Many posts here on this one including mine. If no vacuum at the purple connector going to the vacuum switch under passanger side dash then check WHY. My check valve under the RF fender was cracked. Another $3.48 at Advance Autos HELP section put me back in business, Don't spend money on a compresser etc. that you DON'T NEED. Check out things one at a time and you might save hundreds of dollars. BIGHANK