Air noise from brake pedal

I drive an veteran 1994 F-250 for work. When use the brake pedal, I get a noise like air escaping from below the dashboard. The brakes are a little soft and the front driver side tire is the first to lock up under heavy braking.

Any suggestions

The power brake booster has a leak. Get it replaced before you lose all power assist to the brakes.

Thank you.

I had the truck at a shop that claimed to repair transmissions and brakes. I need a transmission repair. I asked that they check the brakes while the truck was there. The service manager claimed that the brakes worked fine. Knowing this was not correct, I paid for the transmission repair and left. And had the truck towed back to the shop to have the transmission repair corrected.

Now you have two reasons for not returning to that mechanic.

If your truck has an automatic release for the parking brake, the noise could be coming from that system. It may be vacuum operated.

there is a small wad of felt or some other material in the booster where the brake pedal rod goes in . once in a great while it will come out and a loud noise will be heard. it is normal and that is the reason for the muffler material. i’m not saying this is the solution but see if it is missing.