2008 A4 Sline with weird A/C problem

[engineer73]

Has been a while since I have posted and the first time in the A4 section. Maybe someone has run across something like this in the past and can help me out. Just bought my son a 2008 A4 Sline with 84,000 on the dash, the car has been maintained well and is a one owner, here is the issue I am running into. Everything on the car works perfect and it has the dual zone climate control, the heat works fine all of the zones, recirculate and the econo button. but when I switch over to A/C the compressor comes on both fans come on, everything looks good on gauges and the lines are getting frost on them but I have no cold air coming out of the vents. I am very familiar with the C5 but this is new to me, would this possibly be a blend door issue? Thanks for the help in advance.

[Harriz801]

When you switch on the AC, and turn the temperature down to low on both the driver passenger sides does the temp coming out of the vents seem to change at all?

If the lines are collecting condensation, then the compressor is cooling the 134-A, but just sounds like its not cycling through the vents. I think your on the right track with starting to look into the temperature door. My basic understanding is a door that swivels back and fourth between the Evaporator core and the Heater core giving you the different temperatures. I'm not sure about everybody else but I know I can hear my electric motors moving inside the dash when I change settings on my HVAC controls.

Another possibility would be a blocked orifice tube (basically an in-line filter incase you didn't know), not allowing the 134A to cycle through the entire system and reach into the Evaporator core. You'll have to extract all of the 134A from the system to get an eye on the orifice tube though.

[engineer73]

Thank you for your reply, I was just told this evening that the heat is giving him issues now that it has called down outside. I will check the temperature door and post back what I find.

[Harriz801]

Sounds good, keep us posted with what you find.

[engineer73]

Well I finally got some free time and went digging around. I removed the glove box so I could access the passenger side of the hvac box and check the temp / blend doors and their servo motors. Everything looks good in that area, so I turned the A/C on max cool waited for the lines to get cold and condensate but still no cold air was coming out. I pulled the rubber plug out of the hvac box that is used for the glove box cooler kit, when that plug is removed you have access to the evap coil which you can actually stick a few fingers in and touch. When I stuck a finger in and felt the coil it wasn't cold or even slightly cool, so I am at this junction in the road now. Is something plugged up? If that were the case you would think the high pressure sensor would kick out the compressor, but I am getting no codes from the hvac comfort system. Any help would be greatly appreciated, especially since we just had a 78 degree Christmas day.

[Harriz801]

So if you can't feel any temperature difference at the evap core, then I'm assuming there's no condensation coming off of that, at that point?

I would think you were correct with thinking something is plugged up. I would start at the orifice tube first and check there. You'll have to drain the system first, obviously.

When you saw the temp / blend doors, did you try to adjust the temp at the HVAC controls to see if they / it would move? If they don't move, what position was it stuck in? Blocking the heater core or blocking the evap core?