How the problem appears

Start the car with the heat on the climate control wheel is on red the ec or normal or up/down button. Thermostat is fine and new 80C MB original unit. when the car gets hot there is no heat at all. Restart the car the heat is instantly back. Backup in 1min heat dies and stays dead. All this is with the heat control valve on MAX or 26C. Turn the heat control valve back to white or blue the heat turns off as it should. However, turn it back to red the heat does not restart EVER. Turn the engine off and on again heat is back and stays for about 1 min. Rad flushed out. When you drive it the same symtpoms. park the car switch engine on and off heat back on. What the hell is going on?

monovalve is been fixed with repair kit.....