' 93 Ford Aerostar and Brakes Help

When the van is running and is in park and I press the brake down to the floor. I hear what sounds to be air releasing. Once I get all most to the floor it stops. It does this for a few pedal pumps and then has tension
again. Haven't noticed this while driving, but haven't noticed this while in park until the other day. Should I bleed my brakes or could there be some other problem going on here. It seems to me it is like what happens after you change your brakes and you have to pump them to get fluid to the brakes.
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Check 'em. If you didn't do anything to them, then there may be a problem like a wheel cylinder leaking or a pinhole (about to get bigger) in one of the lines. Sounds like there may be some air in there.

the
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the
Shut the van off and hold the pedal down, if it sinks there is a problem. What you are doing doesn't test anything.
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