I have 2017 F150. While driving the temperature gauge dropped to “zero”, an over temp warning came up on the dash and the A/C started blowing warm air. Anybody know what’s happening? Thanks

 

Low coolant allows air to get to the temp sending unit? Did you check your coolant level?

 

You need a new water pump. Happened to me last year $700

 

reservoir is full

 

Take it to a repair facility and have them diagnose the issue... Do not waste time here getting wrong answers from members. As far as the A/C issue, the computer disables unneeded accessories to ensure the engine is under the least amount of stress when it notices a fault.

 

Temp sensor is common. When the coolant temperature is not within spec (or perceived to be withing spec) the A/C will be disabled to prevent additional overheating concerns.
Your A/C didn't quit blowing warm air. The A/C shut off and the HVAC system blew unconditioned air. There is a difference between A/C not blowing cold, and HVAC fan blowing unconditioned air.
Like above, have it diagnosed, or at least have it read for codes. We can guess for 4 days, you can probably get a code read faster than 4 days of guessing.

If you want us to spend your money, we'll tell you you need a water pump and new radiator. And that you will need the A/C compressor replaced.

 

Happened to me. Did you throw any codes? Coolant/cylinder temp sensor faulty after four years. Covered under my CPO and $100 deductible thankfully. Common issue on these trucks.