Noise from dash ac

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Noise from dash ac

October 29, 2017, 06:39:58 am

I have a steady banging sound coming from what appears to be the dash ac. The ac is not on but the banging sound continues unless i turn 12v switch off. Its driving me crazy at 6:30 am.

Re: Noise from dash ac

Reply #1 – October 29, 2017, 07:11:16 am

Joe,

Can you narrow down the area as to where it is coming from? Is the sound coming from the center section or over in the steering wheel area or over at the passengers side?
Have you taken the kick panel off (the removable panel on the right side as you come up the entrance stairs) to see if it is a breaker that is tripping and resetting? Do you know if your coach has an electrical vacuum generator that runs the A/C doors? If so it can short out and cause the breaker to trip and reset. Some might call this a banging sound.

Pamela & Mike

Re: Noise from dash ac

Reply #2 – October 29, 2017, 07:15:05 am

Morning Mike, the sound seems to come from the center. I dont think i have a vacuum generator because my damper motors are 12v. I will pull the breaker panel and see if a breaker is tripping. Thanks for helping.

Re: Noise from dash ac

Reply #3 – October 29, 2017, 07:22:24 am

I have pulled the breaker panel. Does not appear to be a breaker. When it gets daylight I will open generator compartment. Its coming from the center of the coach

Re: Noise from dash ac

Reply #4 – October 29, 2017, 07:24:43 am

Does your coach have an Aqua Hot system? Are you running the A/H system to warm the coach? If so there is a radiator along with your A/C evaporator. Check to see if something has fallen down into the fan causing the noise. If it was something in the A/H fan it would be a rapid sound more like a playing card on a bicycle spoke kind of noise not a banging sound.
Do you know that the center section pulls up to expose what is under it?

Pamela & Mike

Re: Noise from dash ac

Reply #5 – October 29, 2017, 07:26:39 am

Well at least you know it isn't a raccoon in the generator as they aren't powered by the 12VDC system.

Mike

Re: Noise from dash ac

Reply #6 – October 29, 2017, 07:30:46 am

I have primus instead of auqua hot and i have lifted the top of the ac which is the area of the noise. Its a dull noise about a second apart.

Re: Noise from dash ac

Reply #7 – October 29, 2017, 07:37:00 am

That is strange as a breaker will take longer to reset and trip than a second. Even if your batteries were low and the auto start on the generator was trying to start the generator it takes longer to complete it's cycle than that. I'm all out of suggestions for now. Let us know what you find.

Mike

Re: Noise from dash ac

Reply #8 – October 29, 2017, 08:04:09 am

Thanks for trying Mike could not see anything outside. Turned off salesmen sw. To stop the noise. Will have to wait everyone is still sleeping, except me.

Re: Noise from dash ac

Reply #9 – October 29, 2017, 08:36:37 am

By process of elimination it has to be the fan,nothing else is in that area and the fan does run on other settings besides ac.My fan is
right in the middle of the dash.

Re: Noise from dash ac

Reply #10 – October 29, 2017, 09:22:39 am

John, you may be right. I finally got the noise to stop. I played with the switch for fresh air and recirc and the noise stopped as long as the recirc fan is on. I plan to replace all the switches just in case there are easy to get to and should not be expensive.

Re: Noise from dash ac

Reply #11 – October 29, 2017, 09:33:01 am

Sounds like it could be the dash vent / defrost damper motor opening and closing.
Ours is vacuum operated so I cant offer much help on the details of yours......

Re: Noise from dash ac

Reply #12 – October 29, 2017, 10:19:43 am

We recently had the problem with a thumping noise from the dash toward the passenger side. I was able to locate the vacuum generator, laying in my forward cabinet under the passenger seat (we have mid-entry). I put on zip ties on the hose and secured the reservoir and no more problem. Wish all my issues were that easy.

Re: Noise from dash ac

Reply #13 – October 29, 2017, 10:20:57 am

But, vacuum pumps for the dash HVAC system are normally on an "ignition hot" circuit. So, with ignition off, they should not run.

Is yours on a house battery circuit? Chassis battery circuit, but not powered through the ignition solenoid?

Re: Noise from dash ac

Reply #14 – October 29, 2017, 10:52:55 am

Psossible flapper opening and closing from lack of vacuum? I agree with Fourtravelers

let us know what you find

Re: Noise from dash ac

Reply #15 – October 29, 2017, 03:41:16 pm

This fan is controlled by the house batteries. The ignition does not have to be on. Would a bad switch cause the fan to make that noise?

Re: Noise from dash ac

Reply #16 – October 29, 2017, 06:45:49 pm

I wonder if a PO has changed the wiring to the AC controls?
I would have thought that dash AC controls would be powered by the ignition solenoid. I really dont see the need in the dash AC blower needing to run unless the ignition is on and engine running. The compressor can't run without the engine.
It's been a long day.... Maybe I'm missing something.

Re: Noise from dash ac

Reply #17 – October 29, 2017, 07:04:32 pm

You can run the fan without the AC on for fresh air.

Re: Noise from dash ac

Reply #18 – October 29, 2017, 08:45:52 pm

Was that a change made for the Unicoach?

On our GV the ingnition has to be on for the dash AC fan to work. I always leave it in the medium high position and it comes on and goes off with the ignition.

Re: Noise from dash ac

Reply #19 – October 30, 2017, 11:01:48 am

Joe,
Sounds like one of the gear motors went through it's stop and just keeps running with a click every time as it goes through that broken stop. Think there are three of them. I had one do that.
If that's it you will probably have to remove the dog house to change it.
Think I paid around $70 for one from Foretravel ten years ago.
If they have any I would buy two!
By switching to a different vent position that motor would stop.
JD

Re: Noise from dash ac

Reply #20 – October 30, 2017, 01:40:47 pm

Thanks John I'll try different vent position. Will also replace some switches which have seen better days. Dont much like removing the dog house. Its to much work.

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