A common problem for Saab 9-5 is that the engine doesn’t heat up correctly.
This can lead to excessive wear as well as lack of cabin heat. If the engine doesn’t warm up correctly, or if you get no heat to the cabin, this is the #1 thing to check. Here’s yet another great video instructions from the Trionic Seven Saab workshop.
In this video Jonathan fix this problem by replacing the thermostat and He also do a coolant flush: