I had the heater controls from a 1998 Grand Prix out at one time and when I put them back in I plugged every harness that was there back in. It turns out that one of the harnesses only needs to get plugged in to show temperature in Celsius. I don't know if this will apply to a lesabre, but I thought I'd throw that out there.
The 1990 Buick LeSabre air conditioner recharge valve can be found on top of the air conditioning compressor. The air conditioner recharge valve will have a blue top.
I THE WINDSHIELD
The most likely problem is it's out of gas
210 to 220f
It probably is wiring or relay.
You could try learning celsius like the rest of the world. ;-)
By braking it down and fixing all parts
Manifold ait temperature sensor circuit. Year and model?
where is coolant sensor on a 97 buick lasbre
just changed it today, located right side of engine, under to the right of the engine cover , has wires coming off it looking like a bolt,, water will come out when you loosen the bolt.
Trouble code P0116 means:Engine coolant temperature circuit range/performance problem
The vacuum supply line from the engine is disconnected or broken. When the vacuum supply is cut off the system defaults to the defrost mode.