Anytime you open the system to the atmosphere you have to evacuate the system to remove contaminates and moisture.
If your Mercury Sable is stuck on the defrost setting and won't switch to the dashboard vents, it could be due to a malfunctioning blend door actuator or a vacuum leak in the HVAC system. Check the actuator for proper function, as it controls the direction of airflow. Additionally, inspect the vacuum lines connected to the HVAC system for any leaks or disconnections. If these components are functioning correctly, there may be an issue with the climate control unit itself.
I guarentee its a vacuum leak... i had a 1997 sable 174 and 171 all the time turned out to be a vacuum line
Make sure the switch is plugged up correctly, and not up or down just A little,,,,,,,,,,,,,,, If correct, you got the wrong switch.
Get a vacuum diagram from MOTORLIT.COM
how do i change out a power steering switch on a 2001 mercury sable with a 3.0 engine?
location for fuse, and relay switch on a Mercury Sable
You have to diagnose the system to determine the cause. Check the fuses, the bulbs, the flasher relay then the switch.
The 1993 Mercury Sable backup light relay switch can be found beneath the drivers side dashboard. The backup light relay switch will be above the accelerator pedal.
On a 1996 Mercury Sable : The fuel pump shut off switch ( inertia switch ) is in the trunk , behind the trunk liner on the passenger side ( there is an access hole )
The high pressure switch in a 1998 Mercury Sable's air conditioning system is typically located on the high-pressure line near the AC compressor. It is a safety feature that monitors and regulates the pressure in the system to prevent damage or leaks. You may need to consult a repair manual or seek professional help for specific instructions on locating and replacing the switch.
I have the same problem on my 95 Sable LTS
On a 1997 Mercury Sable : The fuel pump shut off switch ( inertia switch ) is located on the passenger side of the trunk , behind the trunk liner ( there is an access hole )