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Where's the sensor(s) for the radiator fan?

Why and how is the AC tied to the cooling system?

I'm trying to learn too.
The computer tells the fans what to do.

There is a fan relay down in the area of the radiator.
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When the engine temperature approaches unsafe levels, the vehicle’s computer or temperature switch turns on the cooling fan relay. The activated relay completes a circuit, allowing an electric current to flow through it and reach the cooling fans.
HOW DOES AN ENGINE COOLANT TEMPERATURE SENSOR WORK?
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On most vehicles, the coolant temperature sensor (CTS) can be found somewhere near the engine thermostat, which allows it to function optimally. The tip of the CTS is probably located right next to the engine coolant.

The sensor works by measuring the temperature that’s being given off by the thermostat and/or the coolant itself. The temperature is then sent to the on-board control system. From there, your vehicle’s computer will use this temperature information to either continue operating or adjust certain engine functions, always working to keep the engine temperature at an ideal level.
Many cars use an A/C pressure switch which, as well as a maximum/minimum cutoff, will turn on the cooling fan if the system pressure rises above a set point. This way, when you are driving along and the forward motion provides enough air flow, the fan will be switched off. If you are stationary and the pressure rises, the fan will activate to increase the cooling air flow and control the pressure.

Other cars simply run the fan whenever the A/C is on.
 

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The Pentastar is pretty generic across the Chrysler lineup. The pictures referenced in Post #2 list the various sensors and where they are located.
I have a Haynes Manual on order, specific to the 5th Generation, there may be more there. The differences between the T&C and Dodge Grand Caravan are mostly cosmetic.
 

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Oil pump output is computer controlled using the sensor inputs for oil and coolant temperatures and other inputs.
The Powertrain Control Module (PCM) switches the pump between stages based on engine operating conditions, oil and coolant temperatures, speed and load. Under most typical conditions, the pump will run in low mode from idle up to around 3,000 RPM, and switch from low to high mode between 3,000 and 4,000 RPM.
 

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If you are wondering what the sensors on the oil filter housing are for, take a look at this contraption:

Automotive tire Font Gas Auto part Engineering


The oil pump used in the Pentastar (3.6L V6) engine is a two-stage design (the volume of oil pumped is not based on pump speed). The displacement of the pump is not fixed; rather, it has a variable displacement capability.

Low pressure mode regulation (solenoid on) is approximately 200 kPa (29 psi) and high-pressure mode regulation (solenoid off) is approximately 450 kPa (65 psi). The Powertrain Control Module (PCM) switches the pump between stages based on engine operating conditions, oil and coolant temperatures, speed and load. Under most typical conditions, the pump will run in low mode from idle up to around 3,000 RPM, and switch from low to high mode between 3,000 and 4,000 RPM.
 
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More complex than it needs to be.
No, it needs to be complex to be efficient and fine tuned to the task. Think 5W-20 motor oil. A more complex additive package to counter wear, but more efficient.
My choice: 5W-30/40
 

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From Haynes Manual?
 

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What I find strange is that the Pacifica pump runs lower pressure, but has more stuff to do with it. You'd think adding VVL would increase the pressure demand. But it's minimum pressure at 3k RPM is half the gen1&2 3.6, and 1/3 across the board on max pressure.
Lighter oil = less pressure? Doesn't sound good for cold startup. I suppose the computer takes care of that.
Oil flow (or heat) seems to be a problem with the Pentastar, hence worn rocker arm needle bearings?
 
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