Brake pedal noise and problems with A/C on

[SLOW04GT]

Here's a weird one for you. When I have the A/C on for around 10 minutes I will get a creaky noise coming from my brake pedal. I can also feel some feedback through the pedal and the brakes feel mushy. If I turn the A/C off it doesn't clear the brakes up right away but it will clear out after about another 20 minutes.

Pumping the brakes I can hear the creaking constantly, whether I am moving or parked.

I thought it might be more heat related but I tried driving in 90 degree weather with my A/C off and I had zero noise or problems from the brakes. It only happens when I turn the A/C on and it has to be on for about 10 minutes. It's like this everyday going to work.

Could condensation from the A/C be somehow working it's way onto the brakes and causing this? I am grasping at straws here

Any ideas?

 

[TestMe]

check your flux capacitor.

 

[ski]

Check for condensation dripping from your car's underside after a few minutes with the A/C on and the engine idling. If not, then the drain pathway may be blocked up, and the condensation may be finding its way onto components that impact the brakes.

 

[Wraith413]

Vacuum leak maybe?

 

[Owner1]

I have the same problem exactly

I have the same symptoms exactly, although I didn't make the link between the A/C and the occurrence of the problem. I just thought it was heat related. Mine did it last summer a few times after I'd been driving more than an hour in hot weather, but when the weather cooled in the fall the problem went away. This summer it does it much more often, but now after only 30 minutes of driving in hot weather.

My brake pads are due for replacement for the first time (120,000 miles) so I'm going to replace them and flush out the old fluid and put new DOT 4 fluid in. If the problem isn't cured, I will investigate further.

Before reading your post, I thought it most likely that since my heavily worn pads had the caliper pistons extended far out of their cylinder, that this and the old brake fluid was allowing for some flex and fluid compression that was only noticeable with the system hot. Now though, I'm not so sure...

How heavily worn are your pads, and has the problem persisted after you have changed pads?

Anyone else experience this?

Thanks,

Owner1

 

[SLOW04GT]

Thanks, Ski. I will try that and see what happens.

Owner1, my pads are still the originals at 28,000 miles. I recently had them checked when the car was in for service and they were fine and don't need replacing. Although I have thought about replacing them anyway just to see what happens. Let me know if is yours is cured after you replace yours.

Mine is still weird though, with it only happening with the A/C on. I'm going to drive it again with the A/C off the whole way and double check that, but so far it has only happened with it on.

 

[Owner1]

NOT A/C related on my car.

I confirmed yesterday that my symptoms occur without having run the A/C at all. It appears to be ambient temperature that sets it off, so running stop and go errands in warm weather will make it occur all of the time now.

My symptoms, btw, are exactly what you described: slightly spongy brake pedal and creaky noise upon brake application, doesn't matter if the car is moving or not. Given time to cool down completely, it goes away.

I will replace my pads and fluid this weekend and will report back as to whether that fixed the problem.

Owner1

 

[SLOW04GT]

Hmm, ok, I bet we have the exact same problem. Mine is either somehow aggrivated by having the A/C on or it's just a coincidence.

Thanks for the update, I'm curious to know what your outcome is. If new pads clear it up I will be doing mine the weekend after next

 

[Blackponies]

Mine is going this also. I haven't corelated it to anything. I think it just does it all of the time but it gets worse when the car is hot. Sometimes worse than others. It is anoying to say the least. When it gets really bad it feels like it may impact the brakes. I have a feeling it has something to do with the hydraulic boost system on these cars. Maybe it only does it when the power steering fluid (that is used for the boost) gets hot. If anyone comes up with a solution I'd love to hear it.

 

[Owner1]

Pads and fluid changed, symptoms are gone

Changed my brake pads (used Hawk HPS) and flushed out all fluid and put in Castrol DOT 4 fluid, and my creaking and mushiness in hot weather are now gone. It has been four days and no sign of the prior problems.

FWIW, my stock pads had 121,000 miles on them, and weren't quite half way used up. Completely even wear on all the pads, inside to outside and front to rear. Best wear patterns I've seen and I've seen a lot.

Owner1

 

[Blackponies]

Sounds great. I'll try a fluid flush. I have less than 50 thousand miles on the clock so I doubt the pads have a lot of wear.