I bought my 2003 Mercury Sable used from someone that parked the car under a locust tree. Locust trees have lots of little leaves that can easily get into small openings.
The air intake area under the cowl grill and the cabin air filter in
my car was full of these leaves and debris.
If your Sable or Taurus has a cabin filter it is located under the
passenger side of the cowl grill cover.
To remove the passenger side cowl grill cover to clean underneath it or to access the cabin filter turn the windshield wipers on and turn the ignition key to on position till wiper motor starts and the wipers are in the up position then turn the ignition key to off position (remove the key) so the wipers stay in the up position. Then remove the four metal clips visible on front edge of cover.
To remove the clips like the one in the left image small groove joint pliers work well. I put tape on the one jaw so I wouldn't scratch up the clip.
I used a thin straight edge screwdriver to get under the clips that sit flush with the cover on top of the clip and my hand to grab hold of the underside of the clip to remove it keeping my hand out of the path of the screwdriver tip in the event the screwdriver slips.
With the front clips removed you carefully lift along the front edge of the cover to removed it. Being careful not to damage the rubber that is attached on the edge of the cover near the hood hinge. Do not use a lot of force to remove the cover.
Here is a closeup of one clip of a another set of four clips that are permanently attached to the underside of the cover.
In this image you can see the four slots in the sheet metal just below the windshield that the cowl grill clips lock into.
Here is a closeup with the cowl cover removed. It is filled with leaves and other debris from the trees it was parked under. Right under the windshield you can see sheet metal then under the sheet metal is a plastic cover, that is where the cabin air filter is located.
NOTE: All the debris around and on the cabin filter should be removed with a shop vac or some type of vacuum cleaner before removing the cabin air filter otherwise the debris will drop into the air intake of your climate control system.
On this car you just lift the plastic water shield panel up to clean and access the air filter.
NOTE: Some model years have the plastic cabin filter water shield screwed down according to my factory shop manual.
On my car the plastic water shield cover over the cabin air filter
can be raised, but only a has a small range of motion.
There are latches built into each side of the cover. To raise the
cover you just pull it up and it will unlatch. When your done you push
the cover down and you should feel it latch when it is back in place.
When this picture was taken I had already vacuumed off some of the debris. This cabin air filter was disgusting and when the climate control system is bringing outside air into the car this is the filter it is flowing through. The filter also had some kind of little bugs living in the pleats. It was its own little ecosystem.
To remove the filter you just lift it up and forward. Even though I cleaned around the filter some debris still dropped onto the screen when I removed the old filter.
Warning: Be careful not to damage the
foam sealant located around the base of the plastic air filter housing
when cleaning debris from the area.
If the sealant is damaged or has failed, the area around the filter
housing will have to be resealed to prevent water from leaking into
the blower motor housing.
I carefully vacuumed the debris from on top of the intake screen to prevent it from dropping through. Looking through the screen, you can see the blower.
Here is the new air cabin filter.
You can get them from a new car, dealer, auto parts store, and at
least one of the large retail stores sells them.
The new filter slips into place, friction fit. The water shield is snapped down in place over the filter.
The new cabin air filter is in place under the water shield. After snapping the filter water shield into place you can replace the passenger side grill cover or you can lift and clean under the drivers side cowl cover.