Had mine checked over, Compressor working fine, noise louder on fan position 3. Switched off air con and put fan on full...no noise so no mechanical or electrical problems. engineer went over it with a stethoscope and could not find where the noise was coming from but by deduction narrowed it down to fluid pressure or miss alignment of ducting causing the whistling. Going to get the pressure checked again and will let you know. Offset your Carbon emissions by boycotting Baked Beans and all Green Vegitables.