Chosen Solution
Lately, my mac book’s fan is spinning a lot faster even though there are no heavy processes running on the background. And when I open FaceTime, I get a message saying that ‘Video will resume when Mac cools down’. I tried resetting the SMC and PRAM, didn’t help. The Mac is not hot at all. The temperature in my area is 22 degree C.
OK at this point we know the issue is not a thermal one but either a voltage issue or a bad fan. Lets try running diagnostics to see if you get an error in the power sensors. Restart your system and press the D key. Let us know if you get an error. Reference: Mac startup key combinations If you didn’t get an error then its time to replace the fan unit MacBook Air 13" (Late 2010-2017) Fan and here’s the guide MacBook Air 13" Early 2015 Fan Replacement. What likely has happened it the tach feedback long within the fan has failed.
Your CPU & GPU are overheating, in most cases this is due to dust accumulation in your radiator which decreases airflow and your fan will start spinning faster and faster, so as @danj suggested you need to install TG PRO and show us the temperatures.
These computers were made to be used on a flat surface bad examples of low airflow surfaces are Carpets, your lap, hot surfaces or surfaces that trap heat such as a blanket. A flat surface such as metal surfaces, cabinets, or tables creates more airflow along with allowing the heat to move to the cooler surface from the metal computer case pieces. If the fan starts blowing loudly it means there is to much heat and not enough airflow. This can mean two things one there is something preventing air from exiting the case, or two there is something sending false temperature readings to the computer.
