Automatic climate control..clack-clack-clack-clack......

I'm...
for several days the climate automatism spins - it does heat, but the temp. is not regulated - from the amature board come loud clack-sounds..sounds after a relay or something...in the same clock as the clacking flickers also the temperature display..there seems to be something to draw..also one hears how the air flow changes...
so there's something crazy about the regulation - it doesn't matter which fashion I take...econ..defrost...always the same.
Someone who's been through this kind of thing?