I've been having a wierd AC situation. Had some work done on the car - new Radiator installed, so they had to evacuate the AC system & ReFill. so now the AC blows cold on full auto - hard, to the point you have to turn it down - it did not seem to want to slow down... when you turn it down and put it on Manual - it blows hot air -then the two vents above the radio are cold and vents by the door are hot. put it back on Auto - and it blows lukewarm across all vents... This is just weird! SO had it with my mechanic - he replaced Shrader valves one was leaking I thought - bingo that it's it. NOPE ... still doing it. SO no codes either. He thought that the dealer may be able to dig more into the computer with their system so its now at FOA... they think it may be the TGK valves? or worst case the stepper motors in the dash... Ugg and $$$$$$ It's never exhibited this behavior before - it's been dead reliable in both heating and cooling. My radiator had a small leak ... so I wanted to make sure I took care of that... so now the car runs even cooler than it did before... only other thing I had done was install air horns - so it beeps as a Ferrari should... I also cleaned out the MAF sensor and the PCV valve etc.. it was oily... but no codes from that..... Anyone else have any HVAC issues to anything similar ?
My car was acting weird for a while too. It behaved similar to yours. I thought steppers as well but the next time I had the car in for service it started working correctly again. My current hypothesis is that there is some startup for the HVAC but I have no real proof of that. FYI: The steppers are available as a PN without the whole unit. I haven't priced them but should be relatively reasonable. Of course the fact that they have a separate PN is a bit concerning. And no, I haven't done my radiator yet so I will get another swing at this one.
I had the same type of event happening on my 612 couple of times. Some of the vents blow hot air (with the A/C on), while other vents blow cold air. We managed to solve it by reset'ing the car: battery cut-off, waiting and restarting. Apparently, some of the HVAC vents lose track of position and need to be reset?
Interesting - I've reset the battery & did a full Negative discharge ... and reconnect and still doing the same thing. .... annoying to say the least. each time I reset the battery - the trunk would not work for a while then after about 30 min - it would work. .... ?
I think the parts are cheap... its the labor to install - tear apart and re instal the dash..... uggggg
So here is the update: Had the TGK valves replaced and A/C is now working normally. so we made it on a 600 mile round trip from Atlanta to Jekyll Island Ga, and back no issues at all. blowing ice cold! all in all it was just under $2K for the repair....
Have the same issue and wonder if I need to remove the whole dashboard or center console is enough to change the TGK valve?
Assuming you have done the basics like system pressures, leak check, etc. I rarely suggest this but start with the power reset. It has fixed more than one system. If that doesn't work, THEN you have to dig deeper. Until then, you are looking for the biggest work without verification it is the problem.
Actually my battery was just replaced which took care of reset. System checked with AC expert, gas inside recovered and it was good amount but anyway refilled with fresh gas and still same. I think now it's down to go deeper?
The good news is that AC isn't too complicated. There is a thread on here, maybe 6-12 months ago, that discussed debugging an AC issue in detail. You shouldn't have too much trouble finding it if you search. NOTE: it may have been in the 360/430 section but I thought it was in this section; that should help narrow the search. I am not an expert on the subject but learned enough from that thread to be slightly dangerous.
You change the TGK valves from the engine compartment. It's next to the oil tank for the sump. The valve has a "relearning" process when power is disconnected. You can check it with a computer to make sure it's functioning properly, or tell it to relearn again.
