noise vacuum? under dash when accellerating

[gordonandpatti]

We have a 2007 Winnebago Voyage on a Workhorse W22 chassis (8.1L Gas).
We have been traveling and today noticed a new sound.
Whenever we accellerated hard or for an extended period, we heard what sounded like a vacuum leak under the dash in front of the driver. The noise stopped right after we stopped accellerating.
What is the noise and is it normal or something to try to fix?
Thanks
Gordon

[gordonandpatti]

We have a 2007 Winnebago Voyage on a Workhorse W22 chassis (8.1L Gas).
We have been traveling and today noticed a new sound.
Whenever we accellerated hard or for an extended period, we heard what sounded like a vacuum leak under the dash in front of the driver. The noise stopped right after we stopped accellerating.
What is the noise and is it normal or something to try to fix?
Thanks
Gordon

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by gordonandpatti:
Whenever we accelerated hard or for an extended period, we heard what sounded like a vacuum leak under the dash in front of the driver. The noise stopped right after we stopped accelerating. </div></BLOCKQUOTE>Gordon, I would suggest that if you have the opportunity to bring this to the attention of a service center that they would be able to help you resolve this condition.

Winnebago uses vacuum hoses behind the dash to control the heater and vent controls controls. Obviously if there were a leak in this system your controls would be compromised and that would present a different problem.

In front of the driver's position could suggest something in front of the fire wall as well. There are a number of hydraulic lines and devices there that could be making some type of sound that could be interpreted on your part as something to be concerned about.

Your WCC service center should be able to assist you with this and I wish you well. Please let us know if you need any further assistance or the name of a service center in your immediate area.

[wilanddij]

Does the noise go away when you turn the AC off? If it does, you probably have a bad condenser clutch, and the condenser needs to be replaced. That happened on my 2004 W20 chassis a while ago. Mine was replaced under WH warranty.

[Tom N]

This should be your heater/AC vacuum diagram.

-Tom

[BellaBo]

Also be sure it's not the electric fans and/or the engine fan engaging. With the recent hot weather recently, it's possible you may have never heard these fans come on before.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Streamerman:
Also be sure it's not the electric fans and/or the engine fan engaging. </div></BLOCKQUOTE>You make a good point however the fans would not be subject to disengagement when the throttle pressure is reduced. Once them babies start spinning up they'll continue to run until the lo-limit is achieved.

[John-D]

Tom N: This is not to the topic but love the "Wheels of Life" sig.

To Topic: There may be a line that has come off somewhere another problem. I have had this happen a few times on cars. Some vacuum lines are "ported" and some are not, ported means that there is little or no vacuum under SOME condtions, (Example, crusing) and a lot under other (Example, acceleration) I would do a good visual looking for an open port somewhere.

[Marshall316]

Gordon,

My 07 W20 does the same thing. It has something to do with the AC. You'll notice that if you turn off the AC you won't hear the noise. Mine usually only does it after accelerating hard, like merging into traffic, or when climbing a long hill.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Marshall316:
My 07 W20 does the same thing. </div></BLOCKQUOTE> Thank you for contributing!

[wilanddij]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">My 07 W20 does the same thing. It has something to do with the AC. You'll notice that if you turn off the AC you won't hear the noise. Mine usually only does it after accelerating hard, like merging into traffic, or when climbing a long hill. </div></BLOCKQUOTE>
Search for a thread here called "Whining while Accelerating". You need a new AC compressor.

[gordonandpatti]

Thanks for the quick responses and all the help.

Stopped for service at a Workhorse GMC Truck service center for another problem;
service manager and Workhorse technician said noise was not engine related;
they thought it was Winnebago installation as part of dash AC system.
It does not go on if dash AC is off, so I'm thinking they're right.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by gordonandpatti:
It does not go on if dash AC is off, so I'm thinking they're right. </div></BLOCKQUOTE>Me too!

[sal avitabile]

my money is on the ac compressor clutch had same problem workhorse changed a/c clutch noise
was gone
Sal Avitabile