Thread: whistle noise behind dash, why?

I've been trying to diagnose this for a couple years now... but last night something happened that made me go ah ha... maybe you can figure it out..

I have a 2008 GP, I had the steering rack replaced in 2010 and oddly since then there was a whistling noise that got louder with acceleration... everyone said it was the steering pump, that was replaced... noise still there... then it was "the hoses are probably clogged" all hoses replaced... still noise... then the rack was "bad" they said... rack replaced... still noise... literally I had every component at some point replaced to stop this noise... not one thing stopped it the good thing that was all done under warranty... well that is gone now and the noise is STILL THERE

but last night.. I was sitting parked idling in a quiet parking lot... the heat was running because it was cold out.. The heat was blowing forward vents only... and the windows started to fog up...

so I switched it to windshield heat... and boom there's the whistle...

thought odd, switched it back to front vents... whistle gone

I have the manual heat controls, not the digital ones so I turned from the furthest left position on the knob (front vents) to the front and floor vents click by click... no noise... got to one click before floor only still no noise...

clicked it up to floor only and I heard the AC compressor come on and the whistle noise started.. interesting...

clicked it back one the AC clutch disengaged and the whistle stopped..

kept going back and forth and got repeatable results

the AC was turned off but the clutch for it still engages when you go to floor vents or higher (goes from floor vents to floor and window to just windshield) anything from floor vents to windshield the AC clutch engages... anything below it disengages regardless of if the AC is on or off...

anytime the AC compressor is engaged the whistle starts

this was done through the entire experiment with heat at max and the blower at max

turn the heat to max and blower to minimum before it turns off... the whistle still starts and is just as loud... so it's not an air flow whistle from the vents... it seems like it's AC compressor related

what in the world would cause this?

I started to wonder earlier in the week because the heat felt colder then usual so I was looking up about Coolant flushes and the heater core now I an starting to wonder if something is clogged somewhere in the AC line that causes the whistle? or coolant related?

the coolant levels are right it appears..

I have no experience with AC but it doesn't feel as cold as it was when I got the car in 2008...

what in the system with these facts could cause a whistle noise when the AC compressor engages?

I can not hear a whistle form the engine bay, only when inside the car

Originally Posted by 02NavyBlue

The orifice tube

oh gawd... if it's the same part as on a home AC unit, I can't imagine this going well getting fixed... I had a clogged orifice at the A coil in my house, froze the A coil into a block of ice...

is something like that easy to have fixed? I assume I'd need a AC person to do it since we are dealing with refrigerant

i get this kinda when my cars WOT but it sounds like its coming out of the air vents. idc much cause its only when im pushing the car pretty hard. btw mines a 2007 so we could have the same problem going on. it kinda sounds like u pull the pressure release valve on an air compressor with about 15 psi in the tank. best way i can describe mine. oh and im N/A

well I know this is an old thread, but I solved the problem finally... on accident

I was losing heat in my car, had a shop do a coolant flush and replacement... still no heat, changed the thermostat also because it appeared to be going bad....

well that was last winter, its getting cold out again and remember I had no heat... ha... so figured ok you know what I'm going to back flush the heater core before I take it in to have someone tell me it needs a new core... did a forward and back flush a few times... pieces of jelly like stuff came out and a lot of gradual sized pieces also... let water run in both directions for 10 minutes each... figured it was good enough, pushed the water out with coolant to prime it put it back together... topped everything off bleed it and boom major heat again...

was out driving it to make sure it burped all the air out and noticed my car was quiet... thought odd.... accelerated and no whistle noise... got home sat idle nothing, turned the wheel where the noise use to go in and out and change pitch, nothing... somehow flushing and cleaning out the heater core fixed the issue! the same issue the dealers could not diagnose and always blamed on the steering pump... (and replaced multiple times!) I guess the tube going through the firewall must of been clogged enough to whistle and since its so close to the center it sounded like it was from the wheel...

uh no it wasn't... it was whistling sitting idle with all the fans off, it was a partially clogged tube

Originally Posted by J57ltr

After re-reading it, your right. Keep an ear out for the whistle when the fans are on high. I was told that GP's didn't get cabin air filters but apparently it started in 04 or 05.

Jeff

yes, the 08 GP has a cabin air filter, which I change yearly

so... after a few years of trying to figure this noise out... it never went away... 2 dealers couldn't figure it out... multiple independent mechanics couldn't figure it out

this weekend I had a lot of "oil" on my driveway but the engine oil didn't go down, the tran did't... brake fluid was fine... but tada the steering fluid res was empty... so I filled it back up got in the car started it up and weird... no noise... no whistle... it sounded like it did when I bought the car... silent...

started to look for the leak, found the power steering return hose line which is right behind the transmission pan and right above the sub frame for the engine on the firewall side looked rusted... looked around and bingo its got a hole in it...

turned out the whistle noise was coming from the return hose assembly... why in the world a dealer never figured this out confounds me... the best part is the issue was caused by the dealer! when they put the new rack in the car back in 2009 (it was leaking when it came from the factory, yeah brand new car leaking fun...) they damaged a few things.... once again ugh... they ruined the rubber boot for the steering shaft... had to have that replaced later because it as letting engine noise in... and they hit the new rack into the steel part of the return hose and dented it... that dent must of created a whistle effect with the running fluid because it changed in tone as the pressure changed when you turned the wheel.. and ironically it rusted through right where that dent was....