basiclly when the a/c is on, the brake pedal is sinking to the floor. now i know what your thinking, brake master cylinder right? ok, but if i turn a/c off pedal works fine/normal. wouldn't it do it all the time if it was the brake master cylinder going bad? could this be a vac leak somewhere? the car is an auto also, so i wasn't sure if there was a sensor that could be bad and attributing to this problem. any help is greatlly appreciated.

thanx.

 

my first guess is...check out your brake booster...

 

so if it is the booster, wouldn't it do it all the time? it seems odd that it's only when the a/c is on.

 

it is normal that the brake pedal sinks slightly when you put the a/c on,, but if yours sinks totally to the floor / you might have internal master cylinder leak

 

Yeah my guess would be the master cylinder to. The fluid get old and full of water condensation and justs the piston in the cylinder so that is can no longer hold a seal and the pressure just bleeds off as you hold the brake down. P Adams helped me with that a few weeks months ago. but my car didn't even have ac at the time.

 

i had the same problem with my m/c...but he says this ONLY happens when he turns on the A/C, if it was the m/c this would be all the time or once in awhile, regardless if A/C was on or not...either this is a bigger problem then we think, or he needs to do a little more diagnosting

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pos_cd5 &raquo;</TD></TR><TR><TD CLASS="quote">i had the same problem with my m/c...but he says this ONLY happens when he turns on the A/C, if it was the m/c this would be all the time or once in awhile, regardless if A/C was on or not...either this is a bigger problem then we think, or he needs to do a little more diagnosting</TD></TR></TABLE>

there is nothing to diagnose ,, brake system is real simple,, if pedal goes to floor,, you got a hydraulic leak on hte system,, or an internal leak on the brake master cylinder..
like i said it is normal for the brake pedal to sink a bit when a/c engages,, but he is saying that it goes all the way to floor ..
does it go all the way to floor ?? or sinks just a bit and he thinks is going to floor ..

Yo thelate if when pedal goes to floor ,, if you pump it up wil it go up and be firm ?? or does it continue to sink to floor ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by accord-pro &raquo;</TD></TR><TR><TD CLASS="quote">

there is nothing to diagnose ,, brake system is real simple,, if pedal goes to floor,, you got a hydraulic leak on hte system,, or an internal leak on the brake master cylinder..
like i said it is normal for the brake pedal to sink a bit when a/c engages,, but he is saying that it goes all the way to floor ..
does it go all the way to floor ?? or sinks just a bit and he thinks is going to floor ..

Yo thelate if when pedal goes to floor ,, if you pump it up wil it go up and be firm ?? or does it continue to sink to floor ?


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i understand what your saying, and i do know how a brake system works...what i dunt understand is why this ONLY happens when a/c is on, from what i know, and from personal experiance with a bad m/c, this should happen all the time, regardless if a/c is on or not..maybe im missing sumthign here, or maybe i dunt understand the brake system as well as i think, so please fill me in...

 

yes, if you pump it it'll get firm.......but will slowly start to sink again.

thanx for the help!!!