air conditioning noise

PAPI · Posted: Wed Jul 30, 2014 6:25 am Post subject: air conditioning noise

Left Boston on Sunday heading for L.A. Just entered Oklahoma, everything looking good! (fingers crossed!) Weird noise from the front when the AC is on. A whine that coincides with engine rpm's. Any ideas?

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

Maybe the noise is coming from the back--a slipping AC belt perhaps.
_________________
T.K.

'88MoneyPit · Posted: Wed Jul 30, 2014 9:06 am Post subject:

Your fan should be high speed. But it shouldn't coincide with the engine rpm

PAPI · Posted: Wed Jul 30, 2014 10:52 am Post subject:

Definitely not the belt or compressor. Noise seems to come from directly under the driver's floor. BTW- just entered Wheeler, Texas.

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

the problem here is that the noise is changing with RPM.
What else could possibly do that except the compressor or belt?

Not the AC fan motor, or radiator fan motor--they would be constant.
_________________
T.K.

kourt · Posted: Wed Jul 30, 2014 11:15 am Post subject:

Yeah, there's not much in terms of moving parts that can make noise with engine RPMs up front.

The tachometer was my first thought. It is driven by electrical impulse, not a cable, so that is ruled out.

The speedometer cable is driven by wheel RPM, not engine RPM. Bad wheel bearings or faulty disc brake parts would oscillate with wheel RPM as well. Make darn sure you're dealing with engine RPM and not wheel RPM.

The radiator fan is two or three constant speeds, actuated by radiator temperature or the AC relay/pressure switch.

I suppose if you had an obstruction or a break in an AC line that passed under the driver seat, or some type of obstruction in the condenser, you might hear it through the floor. All those things are in the vicinity. You would notice such an obstruction through the change in AC system performance. Obstructions usually don't make a lot of noise at the point of obstruction.

Does your van have cruise control? Some cruise systems could make noise.

Some are often surprised by how sounds can be projected by body panels, plastic baffles, or other things under the van. Look for things that are out of place under there. The radiator baffles and the throttle cable cardboard jacket come to mind. Changes to the topography under the van usually result in new sounds which grab your attention.

It helps to know what kind of Vanagon and flavor of AC system we are dealing with. I've assumed you've got the factory "mostly in the back" AC system. If you're running something else, that's important to know.

If you make it to Austin this weekend, let me know--I can help look at this. I'll be working on my AC system and am intimately familiar with Vanagon AC systems.

kourt
91 Westy Bostig
Austin, TX

slackin' at work · Posted: Mon Jul 06, 2015 10:25 am Post subject:

bringing this thread back to life.
Im having the same occurrence.

I just got my AC working in my stock 85 (brand new, tight belts).
nice and cold, yay!

but after my first long drive (10miles+) I noticed a noise from the front.
dependent on RPM. so I thought it might be the transmission since I just hooked up a cooler to it.

but alas, when I turn off the AC the noise stops.

I feel like it's more of a frequency coming from the condenser.
it reminds me of when there is air in your home plumbing.

could it be something like that?

thoughts?
_________________
`20 SQ5
`06 Z4M coupe
`04 R32
`84 MK1 GTI
`76 Brasilia

kourt · Posted: Mon Jul 06, 2015 10:36 am Post subject:

Can you confirm that your electric radiator fan is running when the AC is running? That fan pulls air through the condenser. It is often turned on by the AC, and some folks are surprised by the noise it makes.

kourt

dhaavers · Posted: Mon Jul 06, 2015 11:05 am Post subject:

I attribute this to compressor noise being transmitted through the mount & hoses.

I completely re-did my AC this spring - it never worked before - and this is exactly
how I would describe the sound I've now become accustomed to. FWIW, I did not
re-use the original sound-isolating hose hangers. My new ones just bolt directly to
the frame, and I hear the compressor clearly every time it kicks on...

Without knowing what it sounded like before, I take it as my new "normal"...
_________________
86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS>

slackin' at work · Posted: Mon Jul 06, 2015 11:26 am Post subject:

yes, the fan is running. that I can hear, but am used to hearing it.

it sort of sounds like when you turn your power steering all the way over to lock. sort of a growling, humming, vibration that comes and goes.

I like your thinking dhaavers, "the new normal".
the AC works and is frosty cold… not a transmission noise… every things OK.
_________________
`20 SQ5
`06 Z4M coupe
`04 R32
`84 MK1 GTI
`76 Brasilia

Bassyaks · Posted: Mon Jul 06, 2015 12:18 pm Post subject:

All three of mind do it, I even replaced a compressor thinking that that was the problem, it was still there. I stopped worrying about it , nothing stopped working or burnt up, so just turn the stereo up a click.

kourt · Posted: Mon Jul 06, 2015 12:21 pm Post subject:

I agree with dhaavers--the compressor noise will be heard in the van chassis. My Bostig does this as well. Sort of a growling noise for me. Unsettling at first, and then I feel the cold air and forget about it.

kourt

jfu057 · Posted: Mon Jul 06, 2015 12:29 pm Post subject:

I have the same noise in my '84. My theory, having read a bunch of these posts, is that the early AC that was installed at the dealer (the one not in the Bentley with the hoses run inside the closet) suffers from this symptom.

It seems like people with this unit on early vanagons post that their AC makes the noise and people with other units says there shouldn't be a noise in the front.

Not sure, but mine makes the noise, which seems to come from the condenser fan and definitely changes with the engine speed. Apart from the noise, the system works as I would expect and cools effectively. Have someone push the peddle in when you are at the front of the vehicle and you will see where it comes from.

Maybe it is the sound of a slow death of the electric motor. Or maybe it is compressor noise somehow. Or maybe they installed the fan somehow incorrectly at the dealer.

I also noticed that my AC switch is located on the other side of the steering wheel and the temp control on the switch operates the opposite direction compared to others I've seen here.

Bassyaks · Posted: Mon Jul 06, 2015 2:04 pm Post subject:

I may of missed this but does the noise change with engine RPM or Vehicle MPH?. If it is RPM than I would look at component's , if it's with MPH it could be something as simple as "Prop" noise when combined with airflow.

RBEmerson · Posted: Mon Jul 06, 2015 2:33 pm Post subject:

Engine speed noise from the A/C and the source is up front? That doesn't make sense. I'd start by stuffing a screwdriver onto various points up front, stuff your ear against the screwdriver handle, and see if this crude stethoscope confirms the origin of the noise.

And, of course, check the belts' condition (looking for wear, cracking, chunking) as well as tension. Can't hurt, might help, it's a cheap (potential) fix.
_________________
Lord, give me coffee to change the things I can change, and wine to accept the things I can't change.

slackin' at work · Posted: Mon Jul 06, 2015 2:51 pm Post subject:

Im tending to go with the guys who say it's somewhat normal.

there is high heat, high pressure gas rushing through tubing and the condenser up front.
the RPM changes could simply be the compressor pumping at different speeds.
_________________
`20 SQ5
`06 Z4M coupe
`04 R32
`84 MK1 GTI
`76 Brasilia

vanis13 · Posted: Mon Jul 06, 2015 2:55 pm Post subject:

1 - its normal

2 - (idea) RPM related could be voltage variation to the fan coming out of a not-so-perfect alterntor
_________________
83.5 Westy with Subaru 2.5, 4 spd manual, center seat, COLD A/C on 134a!, Winter camp heated with an Espar B4 gasoline furnace

www.SuperVanagon.com - some stuff I make


Hello! Log in or Register \| Help \| Donate \| Buy Shirts	See all banner ads \| Advertise on TheSamba.com

	Forum Index -> Vanagon	All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1