Guys I need some help I have recently started restoring my 87 635. Just finished the interior and just complete bare metal paint. BBS wheel Upgrad 16x8 and 16x9 ETC. MY PROBLEM: My interior Heater will not keep hot! I believe it has to do with the interior temp sensor which may be damaged. SYMPTOMS: Is hot when at idle and below 40mph(observation) above 40 or when accelerating hard the heat is gone and cold air blows. Please send response for help thanks in advance Tim