when I have my AC on ,and push the brake pedal the pedal goes all the way to the floor . What's the cause of this???

 

ttt

 

Only when you have the AC on?? Those two components are not related in any way I can think of...

 

they arent related. need more info. it doesnt do it when your ac is off ?

 

those components are unrelated in terms of parts.
the only connection i can see is that, IF the weather is hot enough for u to turn on your a/c, that there is a chance that it's too hot that you're experiencing brake fade. the only things you can check is the condition of the brake pads and rotors, and make sure you're not using cheap quality crap on your brake system

 

It's only when I have the ac on and it happened after i changed the seals in the right rear callipers.

 

Either it's just coincidence or you have some stuff hooked up very wrong...Did you change or move anything else around the time you did the brakes? Vacuum line or something?....

 

no I didn't changed anything else but I do remember that when changing the seals all the brake fluid was drained and the reservoir was empty

 

try bleeding the brakes again.
it might just be a combination of air in the system and the high temps causing the fluid to boil causing the brake fade... at least, it's a start.

i'm assuming you're no longer leaking any brake fluid?

 

Doesn't the engine load affect vaccum boost? I notice that when A/C pump cycles on and off the pedal sinks a little if I am at a stop light.