2 problems

first my heater blows some heat on low, but when i turn it up on #3 or higher, it blows cold air, any suggestions?

second i have just been told that my vct soleniod needs to be replaced and parts are 400 and up has anyone else had this same problem?

yo my cat does that 2 but now nothin.. "thermastat" check it..im doin my later... but it can be poor coolant circulation if your car not overheatin...