I have a 2009 Ford Focus SE 2.0l bolted to a 5sp manual. I recently was having dissatisfaction with the vent air being a little cool when the engine was running at operating temp and cab controls all the way on hot. So I hooked up a OBDll scanner and the scanner initially was reading 175 degree F at full operating temp. Therefore, I installed a 185F thermostat. And now, the thermostat is working great. However, I've encountered another problem. The engine is now running hot. Like, when I finish driving it around town 25-35mph zones, I park it, let it idle a couple of minutes and the engine temp rose all the way to 210F. And the problem with that is: the cooling fan never turned on at any point. So I did a little trouble-shooting. I discovered that the single-fan duel speed cooling system's high-speed and low-speed relays are functional. I tested this by swapping them between the two locations in the fuse box. When I turn the A/C on and it actually engages, its relay clicks on, and then the high-speed fan relay kicks on, bringing the actual cooling fan on high speed. But as soon as it kicks on and reaches full speed, it kicks back on off, and it would keep alternating between those two realities. Turn the A/C off and there wasn't a way for me to get EITHER the high speed or low-speed aspect of the cooling fan to work. I was never able to get the low-speed aspect of the cooling fan to engage. I'm new to the Ford Focus community, as I came from GM products. I am fairly knowledgeable & capable of trouble-shooting mechanical (and some electrical) vehicle systems, but this has stumped me. Another thing to note: When the engine had the old thermostat installed, the interior dash gauge ran just left (cool) of center, now, even with the engine running as hot as 210F, the dash gauge still rises to nearly the same physical place and stops there. Do these electronic fans have a cooling relay switch that could be bad? Could this simply be a coolant temp sensor failing and not communicating the PCM that they need to turn on, and the A/C somehow overrides that function to the PCM? Where is the coolant temp sensor even located? No, not the engine head temp sensor, but the actual coolant temp sensor; from my research and understanding, they are different sensors.

I am not one to throw parts at a car, especially when I don't really know what would be my fix. If this was a GM/Chevy/Buick/Pontiac product, I would be a lot more inclined to diagnose and correct the issue. But I am new in the ocean of Ford product dynamics.

I appreciate any and all suggests, insights, and technical advice.