my car is a euro 1989 s124 300td. I have a rotary type aircon. Sometimes, when I start the car, the compressor does not want to turn on. When I try to push the buttons - central vertical row of 3 pushbuttons (demist, air-con compressor enable/disable, recirculate mode). They don't respond - the lights don't go on or off. So, if normally the middle - compressor button is lighted, even if I push the switch, it doesn't want to turn off.

If I turn off the engine and leave it on ignition (before starting), the buttons respond well. However, as what happened earlier, after restarting the car, the compressor is still off. It finally turned on after driving the car for about 10 mins.

Also, sometimes, the blower, when positioned at #1, wont turn on instantly. #2 onwards turns on instantly. Left at speed #1, the blower will work after a few minutes.

I've also experienced the reverse. The compressor is on, the switch is on, but when I try to turn it off, the switch would not respond as well

What could be the problem? Please help

Also, I've replaced these items related to my a/c already about 6 months ago -

compressor
aircon blower
aircon blower switch
evaporator
dryer tank
expansion valve
dryer
fuses