In my opinion your compressor getting warm or compressor have expired so you need to check the wiring and might be any pipe leakage. I will suggest to go nearest car care center to fix the issue. I hope you will get the best advice.
It is not essential to change the brake fluid after 3 years or specific period of time if brake is working fine so no need to worry and brake fluid should to change when it gives a smell due to heating. I never heard about to change the brake fluid.
This is not a common issue it might be two possibilities. There could be a leakage from somewhere otherwise your engine needs a major service because if it is reducing the engine oil so you have to do the major service of your engine.