just in case you feel the need to : RTFM
ac012mnadchaa.pdf (4.8 MB)
Resistance is futile?
Nope: you could replace that glass of water with one…
And if you’re clever about it, you can use another resistor across the temp sensor (parallel) to spoof it in a controlled manner: Coolant Temperature Sensor (CTS) Resistor Trick
You want 13C to read as 20C.
So you need to lower 18000ohm to 12000ohm
1/R = 1/R1 + 1/R2
1/12000 = 1/18000 + 1/R2
=> R2 = 36000
Most flexible solution would be to throw a 50k potentiometer across there.
https://www.amazon.com/s?k=50k+potentiometer
Need Hash room cold? RTFM & add Pot…