My vehicle overheats especially with the a/c on?

Hello,

An engine can overheat due to a number of reasons. It could be for having a faulty water pump, stuck closed thermostat, being low on coolant, inoperative cooling fan, bad radiator.

Having only one fan turn on can make the engine overheat, especially on hot summer days. An inoperative fan could be due to a faulty relay, malfunctioning control module, faulty wiring, bad fan motor. It can also be due to a bad coolant temperature sensor.

Since one of the fans is functional, it is not likely the relay or the temperature sensor.
So, the issue could be bad wiring, faulty motor or even the module.

You will need to check to see if there is power to the inoperative fan harness. If there is power, then the issue is likely the fan motor. You can also provide 12V power directly to the fan to see if it comes.

https://www.2carpros.com/articles/how-an-electric-cooling-fan-works

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.