A/C blows warm air but when temp control ius altered blows cool air.

Hello,
2007 911. When I initially turn the aircon on it blows mildly cool air with the Temp setting on "Lo". If I toggle the temp setting up a few degrees then back down again to "Lo" it begins to blow cold air. What could be causing this? Is this a refrigerant issue or a hvac panel issue? Any suggestions would be appreciated. Thanks.

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[Casey at Pelican Parts]

It's a good practice to start with the refrigerant. These computer controlled systems do odd things when the refrigerant level is low. I have seen: warm air distribution from half of the vehicle vents, temp sensor faults, and stepper motor potentiometer faults caused by low refrigerant levels. Clear all faults after recharging. Once you know that the system has the proper charge you can check faults in the climate control system and work through the relevant test plans.

- Casey

[FPB111]

Strange air con problem - Rennlist Discussion Forums

Maybe the diverter flap is shot. Have you ever had black foam bits fly out of the vents? Even if not this DIY shows a way to look at it from the trunk.
If so there is a good DIY on Renntech
http://www.renntech.org/forums/tutor...the-procedure/

"The flap/door that controls the regulation of air between the AC evaporator and
heater core is a piece of galvanized metal with large holes in it. Then it is covered in
foam...." "the foam coming out of the air ducts in fact comes from the flap/door for the
temperature mix. Mine was 90% gone. Therefore the door was a piece of swiss cheese
with large holes and useless for controlling air flow between the hot and cold sides.
Turning on the AC or heat allowed air to travel right through the door and the door
was basically ineffective. Why I didn't have AC issues this summer is unknown but I'm
sure my fix will have me impressed next summer! If you are losing foam in large
quantities I bet you have lost your heating or cooling efficiency...or you may not know
it yet due to current ambient temps!"