Vaccum problems

digit · 15-10-2006, 03:49 PM

i have a 1999 Falcon AU Forte and i get a hissing noise when i push the accelerator

i have narrowed it down to the vaccum system of the car and the noise is above the drivers footwell - i have pruchased the Gregory's manual but it doesn't show where the vaccum hoses or the reservoirs are.

can someone point me in the direction of the positioning please?

thanks in advance

bodes-sh · 15-10-2006, 03:57 PM

does it affect the braking of the car? ie is it harder to stop than normal? about the only thing that it could be is the brake booster vacuum hose...there's nothing else up there...

digit · 15-10-2006, 04:00 PM

the braking is fine - no probs with the brakes they seem ok

apart from this hissing, the air con switches between the front blowers and the windscreen blower when you push the accelerator hard enough

digit · 15-10-2006, 06:34 PM

any other ideas?

bodes-sh · 15-10-2006, 08:17 PM

what setting do you have the aircon on when it does this? a/c max or just a/c? it could also be that the system is getting low on gas, after i have had my aircon on and i turn the car off i can hear hissing of the system de-pressurising from outside the car...is it a hissing sound or more of a sucking sound?

digit · 16-10-2006, 07:37 AM

its more of a hissing and happens at any time, the air con doesn't even need to be on - and i also get the noise you do when turn the engine off

bodes-sh · 16-10-2006, 06:05 PM

hmmmm, well if you have max a/c on then it's default is recirculated air, whether the recirc button is pressed or not, but i've also noticed mine sometimes switches between the 2, ie fresh and recirc on max a/c, if you can take it to an air con place they should be able to tell you exactly, if it is the air con causing it...

the other thing to look at would be the crankcase breather hose...the one that hooks into the back of the intake pipe before the throttle body, looking from the front of the car, check to make sure it's connected to the intake pipe and rocker cover properly, if it is then pull it off and squeeze all over it and check it for splits, that's about the only other thing i can think of...

digit · 16-10-2006, 06:52 PM

thanks - i'll give it a go, will also get the air con checked out, justed reached 100,000 so its possible it may need the air con serviced anyway

bodes-sh · 16-10-2006, 07:18 PM

no worries, everyone here is always trying to help someone else lol, thats just the way the forums work...good luck with it

oh, slightly belated, should have said it in my first post, silly me...

Welcome to the forums, I hope you enjoy your stay here

blownba · 17-10-2006, 12:24 AM

you have a vacuum leak from the heating and ventilation system somewhere. When you accelerate vacuum in the engine becomes low and cause of the leak behind the dash you have no vacuum reservoir so the vents will change to windscreen (this is default vent setting for when the system looses vacuum) Look up under the dash to the left of the pedals there are 2 vacuum actuators located on the end of the heater box maybee a vacuum line has fallen off one of these ( the vacuum linres are yellow and brown by memory)or the diaphram in one is cracked.If you have the low series(not climate control) there will be a vacuum line running the the blend door actuator cant remember what colour. Also there is a vacuum line that runs to the vacuum reservoir that runs across the top of the pedal box its black in colour check that.

scorpio39 · 17-10-2006, 10:11 AM

I also have a vacuume problem.
No vacuume at the heater hose switch, causing the AC to operate at higher than normal temperature.
I am in the process of removing the radio ( thats another problem as it will only come out 5mm at this stage ) to check out if a vac hose has come off the the temperature switch.
I will now check out the hoses mentioned in the above post.
Anyone else experienced similar problems ?

autickfordfairmont · 17-10-2006, 01:30 PM

I have the same problem/noise above the pedal box. havent had a chance to get under and look yet but same spot. Happened after i took my car in to get a new steering rack installed, dont know why they would have been under there but mayve they knocked a hose off or something.

skap · 18-10-2006, 06:01 PM

Dash out!

digit · 18-10-2006, 07:43 PM

"blownba"

i think you may have sorted the issue - i can only see the brown hose connected to the actuator on the left side of the footwell

never knew about the black one above the footwell so i'll check that out too

thanks to everyone for their advice!

bigmuz · 03-11-2006, 09:09 AM

Hey gang. Good stuff and a recent thread!

I've got an NF Fairlane that is doing exactly this. The hissing on very light throttle has always been there, but now it hisses full time and the air con isn't working, occasionally it does come good though.

I'm praying that it isn't a dash out job, thought I would look here first!

Thanks all, especially blownba.

Muz

slow · 11-11-2006, 10:26 PM

i've got the exact same problem on my AU forte. there's a hissing sound after hard acceleration. around 2000rpm, the air from the blower goes from the vents to demist.

i figured that it was a vaccum prob, but havent been able to find out where its leaking from. i've taken apart the bits behind the air con and fan control on the facia, but still cant find any leaks.

its starting to get really annoying becoz of the hot weather.