Where is the coolant temperature sensor located?

Hopefully the new sensor fixes things.
I keep losing coolant. About a gallon a week. I’ve replaced one temp sensor already. The one in the front under the air intake. I burped the system. I replaced the relays. But, when I put the relay tester on the A/C fan worked, when I replaced the relay, the fan didn’t kick in. None of my fans are kicking in so it’s coming out the overflow. This makes me believe the problem is before the relay. So, I’m just working my way backwards from there and trying the obvious first. My heat and A/C work fine. And all the gauges seem to be okay, but it never gets hot. I usually just fill it up before it runs out. Short trips use more coolant (in town). Longer trips (10 miles) use less coolant. If you have any ideas, please shoot them my way. I don’t have anyone to help me so I’m learning as I go.

Hi, the relay tester plugs into the spot the relay does. Then the A/C fan turns on. The fan does not turn on after replacing the relay. I don’t lose coolant while idling. The shorter the trip the more I lose. I think the air from driving at higher speeds is helping to cool the engine since it’s pretty cold here. I checked my oil several times and there is no sign of coolant getting into the oil. I’m so tired of buying anti freeze and filling the overflow every 10 to 15 miles.

I’m going to replace the thermostat next.
There is no radiator cap, but I did replace the cap on the reservoir/overflow tank. I’ll let you know how that turns out.

Hi. Finally got it figured out. Turned out to be a $5 piece of plastic. The T-connector for the heater hoses and reservoir/overflow was cracked. That’s why it was always wet under the overflow. It finally got so bad I could see the anti-freeze spraying out. Thanks for all the suggestions. Just glad it was an easy fix and not anything serious.