1998 Ford Contour

Look under the hood for a vacuum hose that's disconnected or cracked that feeds the vacuum controls for the heater / AC system.

No havent messed with anything yet. Check engine light came on and i had it checked and code came up so i bought the camshaft sensor to make it go away. They said it was an easy fix so i want to do it myself.

Wrong question sorry wrong i meant to ask i couldn't find a leak should i just change the hose anyway.

If there's no leak, there's no point in replacing a hose. Blowing from just the vents under the windshield is a common problem with vacuum-controlled systems. The various vacuum motors are spring-loaded to go to the defrost position when there's a failure. Your feet might freeze in winter but the windshield will be clear.

Before tearing into the dash to check for vacuum, look for a small plastic hose going from the engine to the firewall. There will usually be some kind of check valve or storage canister inline with that hose. That's a good place to check for vacuum when the engine is running.

If you hear something moving in the dash when you operate the heater controls, there could be a defective actuator or a broken linkage. The clue is some functions will work and others won't. It's when nothing changes and there's no sounds that a loss of vacuum should be suspected.