What could that be ?

Swedishmoose · 03-06-2010, 06:40 PM

Hi there,

I've got a question about a weird noise from behind the dashboard.

It is a Ford Falcon Futura 4 speed Auto ( model year 2000 ) with manual aircon.

Everytime I turn the aircon on it takes about 5 -15 seconds and than you can hear one knock from behind the dashboard. It is pretty loud and you can actually feel the the knock in your left foot when it is resting on the plastic foot rest.

I was thinking it could come from the heater or aircon element behind the dashboard.

Could that be a sticky air duct ( flap ) or something like that ?
But if that was the case it should always do it and not just when I turn the aircon on because all ducts and flaps are operated through vacuum lines.

Is there a valve or something that can get stuck ?

The only difference I have noticed was that it doesn't do it all the time when I first turn on the ventilation fan first ( without turning the air con on ), wait a bit and then turn on the aircon.

If I turn the aircon on right after starting the car it takes about 5-15 seconds...KNOCK...but everything seems to work allright.

I just want to avoid damage in the heater element because its no fun to take the whole dashboard out for crap like that.

Are there any cleaner or lubricants that I can spray into the ventilation system when I put the air distribution switch on recirculation ...like spraying it into the air intake on the passenger footwell side ?

Any ideas what it could be ?

Thank you for any info

cheers

The Moose

mik · 03-06-2010, 10:23 PM

i think it takes a few seconds for the vacuum to build up , hence the sudden movement of the flap, i could be wrong, but i don`t think its something to worry about though.

ronwest · 03-06-2010, 11:08 PM

Quote:

Originally Posted by mik

i think it takes a few seconds for the vacuum to build up , hence the sudden movement of the flap, i could be wrong, but i don`t think its something to worry about though.

Yeah, I think that's right. Mine has always done it (climate control model).

Swedishmoose · 04-06-2010, 02:01 PM

Hi guys...

thanks for your posts.

What worries me that if I change the air flow control switch, all air ducts operate very quietly and smooth....which is good...

But that very loud KNOCK is weird that only appears ones everytime I turn the aircon on ..you can actually feel the vibration in your left foot. It just doesn't sound healthy.

And like I said...if I turn the fan on and wait a bit and then turn on the aircon...everything is allright....
It just happens when I directly turn on the aircon after the car has been parked overnight or for a longer time...you push the aircon button and turn the fan on, the compressor kicks in and after a few seconds that POP noise appears from behind the dash.

Anyways....is there like a dry lubricant spray that I could use and spray into the air intake for the heating system ?

I know there are sprays available to disinfect your aircon from inside...but I don't think they would lubricate as well.

But thanks anyways for the info

The Moose

ronwest · 04-06-2010, 02:12 PM

Quote:

Originally Posted by Swedishmoose

But that very loud KNOCK is weird that only appears ones everytime I turn the aircon on

Hmm, mine is more of a subtle "clunk" definitely not a loud "knock". I'm pretty sure mine only does it 5 secs? after I first start the car (I leave aircon on).

Maybe your flap is sticking a bit. I don't know how you'd free it up, sorry...