Water temp.

My brain is now confused condition to have come across with the unexpected troubles in BC7 SUBARU Legacy LSi US model that happened yesterday. So I would like to describe the affairs one by one to analyze and to specify the underlying cause or causes?

Even 20 minutes after cold starting, the heater system could not be activated at all, the temp meter showed low temp., the cooling fan activation was not checked at that time. No tendency to warm the cabin so far as the heater fan was on, however longer I might wait.

The diagnosis by myself came to the conclusion that the cause must be the fracture of water thermostat construction leading to water leaking.
No critical problem was observed in the original parts. Finally changed into 79 degree celsius set one for PEUGEOT 205 Rallye.

The stylus of temperature meter showed the original position in the cluster at the beginning, suddenly while driving the temp-meter started to rise up to the overheating position.
Stopping aside to check in the engine room supposing warm air after opening bonnet, found I a strange scenery that cooler atmosphere and even a radiator cap was not hot but cold?

Then I started the motor again with water temp at high position and the heater was activated at maximum fan rotation, stylus comes down to the marked normal position.
The result proves the functions of both temp. meter and thermal sensor are normal not being broken.

The temperature at the thermal sensors and the heater core comes up because of any reason and the fan heater is operated to run all the time.

Recent inconveniences are caused by two reasons, some residual bubbles must have done harm to the cooling fan normal activation.
Thermal unit parts on the #4 cylinder may be broken to have shown pseudo temperature of LLC.