Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Eiska on 01 February 2024, 06:39:02

Title: Hvac on Defrost only and whine sound
Post by: Eiska on 01 February 2024, 06:39:02
Hello
Couple of days ago my Omega B 99 started having a high pitched whine sound inside the dash and my hvac is stuck on the windshield mode.
It blows very well but i cant change the mode.

Pressing on the gas quiets the whine down almost completly.
Changins modes on the hvac does something to the whine but the whine is still there.

So whats wrong with it?

Thank you
Title: Re: Hvac on Defrost only and whine sound
Post by: TheBoy on 01 February 2024, 15:07:10
By not changing modes, does the display on the heating panels change with your button presses, but the air still comes out the windscreen vent, or does the display on the heating panel not change with button presses?
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 01 February 2024, 15:39:59
Have you tried pressing the OFF button and then switch it back on  :-\

Also what happens if you press the windscreen button again :-\

High pitched whine may be something coincidental, possibly aux belt related if it quietens down with rpm.
Title: Re: Hvac on Defrost only and whine sound
Post by: Eiska on 01 February 2024, 17:08:35
By not changing modes, does the display on the heating panels change with your button presses, but the air still comes out the windscreen vent, or does the display on the heating panel not change with button presses?



I do t have a display just 4 knobs and seat heaters, rear defrost, hazards, heat circulation and ac
Title: Re: Hvac on Defrost only and whine sound
Post by: Eiska on 01 February 2024, 17:17:15
Have you tried pressing the OFF button and then switch it back on  :-\

Also what happens if you press the windscreen button again :-\

High pitched whine may be something coincidental, possibly aux belt related if it quietens down with rpm.

I dont think i have a ”off button” i just have 4 knobs and seat heaters, ac etc
And the whine can be only heard onthe inside not outside so it cant be the aux belt.
Title: Re: Hvac on Defrost only and whine sound
Post by: TheBoy on 01 February 2024, 18:07:17
By not changing modes, does the display on the heating panels change with your button presses, but the air still comes out the windscreen vent, or does the display on the heating panel not change with button presses?



I do t have a display just 4 knobs and seat heaters, rear defrost, hazards, heat circulation and ac
Ah, so its a pre facelift model.

Could well be the vacuum pipe has come off the back of the air distribution dial, or other vac related problems.
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 01 February 2024, 18:08:40
Ok, so mid facelift. If knobs then check the cables move freely. And actually move the various flaps.

I don't see how applying throttle would affect a noise in the cabin though.
Title: Re: Hvac on Defrost only and whine sound
Post by: TheBoy on 01 February 2024, 18:12:54
Ok, so mid facelift. If knobs then check the cables move freely. And actually move the various flaps.

I don't see how applying throttle would affect a noise in the cabin though.
Its vac operated, not cable operated.  Unless my memory is worse than I thought!
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 01 February 2024, 19:07:48
Ok, so mid facelift. If knobs then check the cables move freely. And actually move the various flaps.

I don't see how applying throttle would affect a noise in the cabin though.
Its vac operated, not cable operated.  Unless my memory is worse than I thought!
Only ever had the far superior facelift with it's new fangled dual zone digital climate control...

Using vacuum to connect mechanical knobs to mechanical levers sounds like something ze Germans would do... Oh wait ::)
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 01 February 2024, 19:21:04
Well... a quick rummage in the book of lies suggests that it is indeed a vacuum control system  :o

So a vacuum leak or broken/jammed/binding actuator is going to be the likely culprit.
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 01 February 2024, 19:37:49
Vacuum unit defrost valve - brown vac hose.
Vacuum unit foot well valve - green vac hose.
Solenoid valve control unit - wiring connection to recirculation button, blue vac hose.
Vacuum reservoir - engine vac - yellow hose.

And that's your lot.

Applying vacuum to the first three hoses should confirm movement.

Any other work done recently?
Title: Re: Hvac on Defrost only and whine sound
Post by: TheBoy on 01 February 2024, 20:10:52
Well... a quick rummage in the book of lies suggests that it is indeed a vacuum control system  :o
Phew, I'm not going bonkers....
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 01 February 2024, 20:17:23
Well... a quick rummage in the book of lies suggests that it is indeed a vacuum control system  :o
Phew, I'm not going bonkers....
Give it time :D
Title: Re: Hvac on Defrost only and whine sound
Post by: Eiska on 02 February 2024, 07:49:41
Vacuum unit defrost valve - brown vac hose.
Vacuum unit foot well valve - green vac hose.
Solenoid valve control unit - wiring connection to recirculation button, blue vac hose.
Vacuum reservoir - engine vac - yellow hose.

And that's your lot.

Applying vacuum to the first three hoses should confirm movement.

Any other work done recently?


Is there a picture for these? A schematic?
I fid some radio wiring work and kinda used force to cram all the wires back inthere so it would make sense that something is loose in there
Title: Re: Hvac on Defrost only and whine sound
Post by: Eiska on 02 February 2024, 07:51:53
By not changing modes, does the display on the heating panels change with your button presses, but the air still comes out the windscreen vent, or does the display on the heating panel not change with button presses?



I do t have a display just 4 knobs and seat heaters, rear defrost, hazards, heat circulation and ac
Ah, so its a pre facelift model.

Could well be the vacuum pipe has come off the back of the air distribution dial, or other vac related problems.


Is it easy to get back there to the air eistributuon dial? Or do i have to pull the whole dash out?
I did some radio wiring work and cramed all the wires back in so it would make sense that the proplem is somewhere in the center console/ radio area.
Title: Re: Hvac on Defrost only and whine sound
Post by: Doctor Gollum on 02 February 2024, 11:52:12
By not changing modes, does the display on the heating panels change with your button presses, but the air still comes out the windscreen vent, or does the display on the heating panel not change with button presses?



I do t have a display just 4 knobs and seat heaters, rear defrost, hazards, heat circulation and ac
Ah, so its a pre facelift model.

Could well be the vacuum pipe has come off the back of the air distribution dial, or other vac related problems.


Is it easy to get back there to the air eistributuon dial? Or do i have to pull the whole dash out?
I did some radio wiring work and cramed all the wires back in so it would make sense that the proplem is somewhere in the center console/ radio area.
Sounds like you've either skewered or otherwise damaged a vacuum line. At least you know where to start looking.

If it is a dash out job, expect to be busy. Perfectly doable, just take your time. And if it comes to that, replace the heater matrix at the same time as it will be a piece of piss to do with the dash out and you'll be an idiot not to replace it under the circumstances.
Title: Re: Hvac on Defrost only and whine sound
Post by: TheBoy on 02 February 2024, 18:27:35
I would imagine it will just be the vac lines on the control knobs, so only need to remove the centre console, which is straightforward.

And when you put it back together, don't ram it in when clearly it isn't wanting to sit right ;)