is this normal?

[skull1441]

i have my AC on.... im holding down the brake.... i hear the AC relay disconnect ( normal thing then it reconnect again )... now .. my question is.... why does my brake pedal sink down a little when the AC relay does its automatic disconnect thingy???????........ hope this makes sense

[smufguy]

i have my AC on.... im holding down the brake.... i hear the AC relay disconnect ( normal thing then it reconnect again )... now .. my question is.... why does my brake pedal sink down a little when the AC relay does its automatic disconnect thingy???????........ hope this makes sense

u mean under constant brake pedal pressure, you experience sudden extra play when the ac disconnects? Well the brake works off the vaccum from the manifold, the brake booster i mean.

when the ac is on and working, the engine speed is a little high and thus the vaccum is a lil high. so the pedal pressure needed to stop the car is less. imagine u driving at 60 miles an hour and u tap the brake and the car brakes.

and when the ac is off, the engine speed drops and the vaccuum drops too. so the pedal goes in to compensate for the decrease in vaccuum. its a normal thing and not to worry about.

But if the pedal play is too much. like it just hits the floor board, then u got a master cylinder problem and/or air pockets in ur brake lines.

[skull1441]

ok makes sense..... but no it only goes down like 1 or half an inch

[smufguy]

ok makes sense..... but no it only goes down like 1 or half an inch

then ur good.

[Jareds 89 LX-i]

Smuf, you're exactly right! Mine does the same thing too. But just to nitpick what you mentioned, you had your vacuums backwards. When engine speed rises, vacuum lowers, and when engine speed slows, vacuum goes up. Just wanted to clarify

[smufguy]

oh yeah, my bad. hehehe, thanks jared. Now ill just go and sit in a corner lol