2000 Mercedes-Benz M-Class - HVAC Occasionally Blows Only Hot

The Car’s (2000 ML430) HVAC only randomly blows heat air, and won’t blow cold air after turning the climate control nob to cold air. I’ve replaced the air blend motor actuator and it’s still randomly changing from blowing cold air to hot air, or just blows hot air . Any help would be great. Thanks.

Could be a bad climate control computer.