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The Volvo Factory Manual I have on the Construction & Function of the CI System states that the AAV fully opens at -30C/-22F . The book also states that the valve is fully opened at +70C/158F or after the equivalent of running the engine for five minutes at an ambient temperature of 20C/68F . So basically unless it is colder than cold then all you would see is that cresent shape opening. As far as your idle problem it seems that the AAV is not your problem but that you may have extra air leaking in between the air flow sensor and the intake valves. Any leaks in between cheats the air flow sensor thus not allowing it to raise enough to provide a richer mixture when it really needs it.
Another possible cause could be a gummed up Control Pressure Regulator. If the CPR is gummed up then the plunger on the fuel distributor is being pressed down all the time. The purpose for the CPR is to relieve the pressure on the plunger when cold by means of a bi-metallic piece of metal pushing down on a spring. This piece of metal (when cold) pushes down on that spring allowing more fuel to return back to the tank thus lowering the control pressure on top of the plunger making it easy for the plunger to move up with less air flow causing a richer mixture. As the car warms up a small heating device wrapped aroung the bi-metallic spring warms it up causing it to bend after about 5 minutes. When the metal bends the spring force ends up winning and thus restricts the flow of fuel back to the tank causing a greater amount of control pressure on top of the plunger making it harder to richen the mixture. My 1979 264GL has a gummed up CPR and I have the exact same problems and my CPR is currently soaking in a bath of TECHRON till tomorrow. PHEW!!!
The following links will take you to previous posts that teach you how to clean the CPR.
a href="http://brickboard.com/ARCHIVES/1997DEC/6460.shtml">Link #1
a href="http://www.brickboard.com/ARCHIVES/1998AUG/20008879.shtml">Link #2
I hope this info helps and post back any results or question you may have. By the way the book where I got all the knowledge from is for sale on Ebay. Good Luck!
Sincerely,
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Nickvjr 1979 264GL B27F 121K Features Added: Central Locking System, 25mm IPD Front Sway Bar, 81+ Dash W/ Oil & Ambient Temp Gauges In C, Oil Pressure, Volts Next Project: Add Cruise & BW55 Swap To A M46
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