I have had a number of problems with the A/C control on my 1988 420 SEL. If I have the heater giving warm air and then select a cooler temp, I can't get the heater to go back to warm without an ignition cycle. I also have a problem keeping the fan running in auto or low. Auto works ok when min temp is selected. The fan usually won't turn on initially in any selection, although if I move the ignition key slightly while tapping the brake it will come on. The A/C compressor will only work about half of the time, but when it does it cools just fine and usually keeps working. I replaced the push button control unit, but still have the problems. Any help would be greatly appreciated.