BMW Repair: bmw repair, bmw repair, bmw owner

Question
I have a 1989 535i AND DEVELOPED A LEAK IN THE HEAT EXCHANGE. i WAS TOLD i CAN GET IT REPLACED, BUT IT WOULD COST MORE THAN THE ENTIRE VEHICLE IS WORTH.  i THEN HEARD IF i DIDN'T NEED THE HEAT TO EVER WORK AGAIN, WHICH i DON'T.  YOU CNA DO  BYPASS. lET ME KNOW IF THERE IS ANY OTHER DOWNSIDE IN DOING A BYPASS AND THEN WHICH OF THE HOSES SHOULD BE PUT TOGHETHER WITHIN THE BYPASS.  aLSO. MY AIR CONDITIONING ISN'T RUNNING COLD.  i CONVERTED MY CAR TO 134 INSTEAD OF R18 AND THE SYSTEM TESTS FULL.  WILL THE HEAT EXCHANGE BYPASS HELP THIS AT ALL.   THANX ALOTFOR YOUR ANTICIPATED RESPONSE.

Answer
First off I cannot believe being a BMW owner that I would put any repair above the value I think the car us worth.You have change the R12 into  the new R134.You do like the cooling(if it worked).There maybe a connection with your heat and a/c. I don't understand your "heat exchange" issue.There is a valve that opens and closes for heat,and most times replacing the diaphragm takes care of that problem.Besides that I am at a loss.Remember not to get to complicated in these cars as they are not.