Blend door issue. Usually the actuator failing.
It's a small motor on the top of the HVAC duct, behind the dash.
Cars with manual controls (your p71) use the white version.
Cars with automatic EATC controls use the black version.
There are two methods for replacing this part.
One method is to remove the glovebox and passenger airbag.
You then reach in (tight space) and remove the two 8mm screws. There is a third screw which you will break the old actuator off of.
Once the Actuator is out, you can loosen that third screw a half turn.
On your new actuator, cut a slot in that screws hole so that the actuator can be slipped in place. This method takes about 45 minutes, but involved lots of cursing.
The other method is to remove the dash. This is much easier than it sounds, and will take two or three hours.
Here's the step by step.
-Three 7mm screws along top under windshield/defrost trim
-11mm nut by passenger door
-radio antenna coupling under glovebox
-Police Power Connector under glovebox on p71s
-Three 8mm grounds behind passenger kick panel
-Two electrical connectors behind passenger kick panel
-Two 13mm bolts on driver side of transmission tunnel
-one 15mm nut connecting diagonal brace to steering column
-one 13mm bolt connecting steering shaft to column
With this out, the passenger side of dash can be pivoted out and set on passenger seat.
I recommend replacing the heater core while you're there.
-disconnect heater core hoses, either 7mm hose clamps or squeeze clamps
-detach white vacuum line (recirc door) from HVAC box
-unplug blend door actuator
-three 11mm nuts attached HVAC box to firewall
-Five 8mm screws hold heater core to HVAC box
-three 8mm screws hold blend door actuator on HVAC box.
Do not test the blend door actuator unless it is secured to the HVAC box. The door itself acts as the travel limits. If not attached, the actuator will over travel and the gears will fall out of place.
Member of Northwest Panthers Car Club
2008 P71, Norsea Blue SAP
-Message Center cluster retrofit
-Towncar Signature L heated power seats
-Long overhead console
-Compustar remote start/security