Vibrating/Growl Noise when van AC turned on

billj

MR BILL
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Make
Ford
Model
E350
Year
2006
Miles
187,000
Engine
5.4 liter
2006, Ford, E-350 Super Duty Van, 5.4 liter, 187,000 miles. When AC is turned on, or set at on when starting, it makes a vibrating/growl noise for a few seconds, and may do it twice a few seconds apart. This happens only when engine is at starting RPM@ 1,200. If engine is allowed to idle down to 750 RPM and then turn on AC there is no noise or vibration.
I have replaced the AC clutch hub, the serpentine belt, and the belt tensioner.
 

Mobile Dan

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Maybe there is too much oil in the compressor. Low-mounted compressors have this problem if system oil "settles" in the compressor when system is not running for hours or overnight.
 

billj

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Maybe there is too much oil in the compressor. Low-mounted compressors have this problem if system oil "settles" in the compressor when system is not running for hours or overnight.
It is a low mount compressor. By the way low side pressure at idle, at operating temp engine, is 30-32. Middle cold vent temp 45 degree Fahrenheit. Does the entire system have to be evacuated to drain excess oil out of the compressor?
 
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billr

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Did this noise just start recently, with no recent work on the A/C system? It is unlikely (impossible?) that any "extra" oil got into an operating system.

Yes, to get oil out you have to open the system up to some extent, maybe disconnect components to drain all and then re-fill with specified amount. Figure on having to do a vac and re-charge.
 

billj

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Did this noise just start recently, with no recent work on the A/C system? It is unlikely (impossible?) that any "extra" oil got into an operating system.

Yes, to get oil out you have to open the system up to some extent, maybe disconnect components to drain all and then re-fill with specified amount. Figure on having to do a vac and re-charge.
The noise started a couple months ago, with no work done on AC unit. One 12oz can of R-134a needs to be added about once a year. I have a professional high/low pressure gauge kit. I am careful not to overfill system.
 

billr

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My opinion? The compressor is getting worn, but you could put a lot of time/money into chasing this down. I would let it be, as long as it still cools satisfactorily, until the problem is more identifiable. I would also be sure to not start up the A/C until idle is down, to avoid the ugly noise and any further damage it may be indicating...
 

billj

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My opinion? The compressor is getting worn, but you could put a lot of time/money into chasing this down. I would let it be, as long as it still cools satisfactorily, until the problem is more identifiable. I would also be sure to not start up the A/C until idle is down, to avoid the ugly noise and any further damage it may be indicating...
The AC works great, cools very well. Your thought are about the same as mine. Turn the AC on only at low RPMs and wait until there is something more definitive. Thank you.
 

dabunk

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My .02 though with Fords, when when the compressor really goes it sends metal black death through the whole system. And it is a real B###ch to clean everything out. So not always best to wait until it dies
 

paulo57509

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My .02 though with Fords, when when the compressor really goes it sends metal black death through the whole system. And it is a real B###ch to clean everything out. So not always best to wait until it dies
Compressor failure in GM cars will do the same thing. You're talking a lot of time, effort and money to remove components and properly flush the system.
 

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billj

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One more note: It doesn't make the noise every time. Today I made several start/stops, some a few minute stop, some an one hour+ stops and it never made a noise when starting with AC set on MAX. (The first start of the day was done with AC off.)
 
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