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New Sanden squalling above 3000 rpm


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dogbone
New User

Aug 9, 2017, 7:51 AM

Post #1 of 9 (563 views)
New Sanden squalling above 3000 rpm Sign In

Here's the story, I need some suggestions. I've just revived the A/C on my 1964 Ramber Classic stationwagon. It's pretty much a clean install with new condenser, dryer, expansion valve and new Sanden 508 compressor. I used the original evaporator but flushed it well to remove any old oil and trash. I pulled vacuum for about 6 hours then charged the system with three cans of R134a. It's cooling great. Outside temp is 90 degrees and I'm getting 45 out of the center vent, sometimes going down to 39. Low side pressure is running 15-20, high side 250 at 1500 or so rpm. I can drive it around and it works fine, but I've noticed when going over 3000 rpm the compressor really squalls. Sounds like a dry bearing vibrating in something. I've checked to make sure it's not the belt slipping or the clutch. The sound is definitely coming from the compressor. I can feel the vibration on the suction hose.

The compressor itself was full of oil from the factory. I have added about 3 oz of oil to the system. The compressor has a little smaller pulley than the engine pulley so I'm sure it's being overdriven slightly. It's rated to 6000 rpm and I'm sure It's no where close to that.

Is it possible I just need to add more oil? I know putting too much oil is a problem. Any suggestions would be appreciated. Thanks


Discretesignals
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Aug 9, 2017, 8:07 AM

Post #2 of 9 (558 views)
Re: New Sanden squalling above 3000 rpm Sign In

Might be a defective compressor. Hopefully its not sending metal into the system.





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Sidom
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Aug 9, 2017, 12:26 PM

Post #3 of 9 (539 views)
Re: New Sanden squalling above 3000 rpm Sign In

What's the hp reading @ 3000 rpms?






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dogbone
New User

Aug 10, 2017, 6:17 AM

Post #4 of 9 (509 views)
Re: New Sanden squalling above 3000 rpm Sign In

At 2000 rpm the low side is around 6, high side 250. It stays the same at around 3000 where the sound kicks in. It a steady reading.

Idle pressures are 16 low, 270 high. And the air temp is running 38 to 46 degrees.

I've heard that Sanden 508's are all noisy above 2800 rpm?


Hammer Time
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Aug 10, 2017, 10:46 AM

Post #5 of 9 (497 views)
Re: New Sanden squalling above 3000 rpm Sign In

Your high pressure readings are lower at 3000 than at idle? Are you sure about that?



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Sidom
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Aug 10, 2017, 11:20 AM

Post #6 of 9 (489 views)
Re: New Sanden squalling above 3000 rpm Sign In

Just a couple of thoughts...

My 1st though was you may be overcharged and that was why it was making noise at high rpm.....Without a recovery machine it's a bit tough but I would evac the system and start with 1.5 lbs and check my readings and temps......

6 on the low side with the comp still running is pretty low....I'm guessing your TXV valve had a sensing bulb on it?.... Is it in a good spot to read the correct evap temp?

I'm assuming the belt is good and tight.....any doubts and tighten it some more and see if that makes a difference






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Tom Greenleaf
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Aug 11, 2017, 12:09 AM

Post #7 of 9 (472 views)
Re: New Sanden squalling above 3000 rpm Sign In

Just on the belt with the noise complaint: V belt may not have proper contact for full grip even if tight enough? Pulleys need to match wear and angles could slip some and still strong enough for that high pressure.


I think you can test that with light paint and see where it wears that off in no time. Also a new belt if so would have rapid change in tension from were it was first set to be checked again.
Did you mean "squealing" as "squalling" isn't a word I would use for a noise description?


If oil not moving usually knocking sound and high risk of destruction and debris not showing that by pressures quite yet but think it would soon?


T



dogbone
New User

Aug 11, 2017, 11:39 AM

Post #8 of 9 (453 views)
Re: New Sanden squalling above 3000 rpm Sign In

I'm going to go back and double check everything, belt, brackets etc.

Would overcharging be more of an indication on high side than the low?

It's not a belt squeal. It's more mechanical.


Tom Greenleaf
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Aug 11, 2017, 12:09 PM

Post #9 of 9 (451 views)
Re: New Sanden squalling above 3000 rpm Sign In

Charging info is listed here up top. You look for high side to be about 2.5 times the temp F. of air coming in thru the grille is what the car knows it's dealing with.


With expansion valves low could be screwy but not way too low in 20s maybe 30s PSI. There's a direct correlation of temps and pressures all throughout system not to be too low or if converted with a high pressure switch not too high on high side or would shut down compressor which is up there over 350 or more. After that much it should have a blow out valve so it doesn't just climb forever.
The risk is also choking a compressor with liquid if things are all wrong usually too much refrigerant in this case 134a. That doesn't use the sight glass if equipped as much as calculating temps and pressures at what RPM plus output temps taken at center vent.


It's a whole course of study with whacked exceptions that experience is the teacher just don't let learning be at the cost of a compressor and junk inside downstream.


Noise if not choking and belt you can just spray with water should shut up proves it's not the belt grooves, alignment of the pulleys or wear on one. One in a few belts will just make noise because it's junk new or not and compressor if not treated properly and spun with oil prior to start up and fast charge could burn out. Just know, oil in with refrigerant doesn't move unless the system is operable enough to produce cool or at least condense gas to liquid to go thru the loop of the system.


In short - it could be a bad compressor and to see it making junk off it comes and dump out oil into a clean jar is NOT what you want to see. Bearings of shaft are bushings I'm pretty sure. Clutch is a separate sealed bearing not involved while compressor is engaged ONLY when it's off. Got it?
Tom







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