Cars Q&A

FORD IKON 1.3 LITERS PERTOL ENGINE BRAKES ARE WORKING NORMALLY AND FINE HOWEVER WHEN AC IS TURNED ON AFTER A FEW MINUTES AS THE COOLING STARTS BRAKES START BECOMING LESS AND LESS EFFECTIVE. FIRST U CAN FEEL BRAKES ARE BECOMING LESS AND LESS EFFECTIVE AND AFTER A WHILE THE BRAKE PEDAL BECOMES HARD AND HARDLY ANY BRAKING IS THERE.ITS A NIGHTMARE DRIVING AND I HAVE TO IMMEDIATELY COME TO LOWER GEAR AND APPLY HAND BRAKE AND PRESS THE HARDENED BRAKE PEDAL TO GET BRAKING. WHY IS THIS HAPPENING PLEASE ADVICE AS THIS IS CRITICAL IS IT THAT THE BRAKE BOOSTER UNIT IS WORKING FINE WHEN AC IS OFF AND SOME HOW FAILING PARTICULARLY ONLY WHEN AC IS SWITCHED ON PLEASE HELP