Temp gauge pegs left and a/c when runs overheats engine

Use a digital multimeter--ohms setting, sensor unplugged. check the resistance across the two wire terminals on sensor. As the sensor/engine heats up the resistance should be less. From cold to hot if no resistance change then either the sensor is faulty or there is air in the system. If the resistance does change, then check the wiring connector--wiring circuits-- or the instrument cluster may have a problem? Just my opinion.
Any applicable trouble codes?

go to autozone rent the free tool called a block tester buy the fluid for it (about $8.00 us)drive the car make sure the resivour is about 3 inches down so you dont suck any fluid into block tester. pour blue fluid into block tester put it in antifreeze resavour. squeeze bulb sucking air from resouivour for up to 2 minutes if fluid turns yellow your head gaskets are leaking. I think you may find this to be your problem

For car running hot and overheating issues, I suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems: ----Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
----------This details will help.Thanks.

most likely problem for the fuel guage is the sending unit. The temperature sending unit should be easy to get to. depending on the motor, it is going to be a one wire connector going to it, most likely on the lower intake manifold. Once you find it. connect a jumper wire to it from the NEG battery terminal. It should peg out on hot, which would mean a faulty temp sending unit.

as for the temp gauge all rangers that i have seen run so cool that the hardly move from the c unless u have a major overheat as for the fuel gauge it could be the descending unit in tank and the speed cable is not to hard to change hardest part is removing the instrument panel

Sometimes this works, ABS light on, check engine light on, speedometer not working, and the automatics start shifting hard or not shifting at all? One bolt and the part is cheap, its weird how one part controls so much.

ok mine did this untill i got an air pocket out of the coolent system then it was find.

sounds like you have a bad temp. sending unit. Go to a parts store and have them scan your computer and they can translate the code and tell you for sure. Check your coolant and make sure it is full and clean.

My mechanic has had my Silhouette for two weeks for the same problem. Engine Tempurature is running at 195 degrees when the gauge is pegged on overheat. Normal operating temp for this van is 220. So it is not overheating. Had the cooling/heating system flushed and refilled, bled and topped off. Still the gauge is up and down like a yoyo. Still looking for answers.

sounds like a fuse