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Truck made a strange noise at start-up the other day.
Similar to a belt squeal, but definitely different
I checked the belt, (even though it is new)

There was a glob of something on the surface of the idler pully which I cleaned off but that didn't cure it.

I noticed a black gummy substance at the boundary of the inner and outer portions of the AC compressor pully, so:
I turned off the a/c and restarted then the noise went away even after I turned the a.c. back on.

Any ideas?

Edit:
The a.c. clutch functions / stops if I pull the clutch relay fuse.
Does the A/C compressor spin and compress?
Most of the time idler pully bearing.
Originally Posted by FatCity67
Most of the time idler pully bearing.

Had a few idler pulley go bad & squeak, also had a water pump squeal before it went.
Originally Posted by CCCC
Does the A/C compressor spin and compress?


It spins and idles with the clutch disengaged/engaged (or is the clutch action reversed on a.c.?) Using the relay fuse to trigger the magnet.
So
It does cycle on and off (I haven't watched it long enough to see if it auto cycles..

It seems like the seats blow cold, but not the dash

As far as compressing, I suppose I need to borrow a set of gauges to test the high and low sides.
Originally Posted by Jiveturkey
Originally Posted by FatCity67
Most of the time idler pully bearing.

Had a few idler pulley go bad & squeak, also had a water pump squeal before it went.


I pulled, checked and lubed all the idler bearings when I did the belt and they are all quiet.

My primary concern was the black stuff at the clutch/pully interface..
I don't see how system fluids (oil /coolant) could come out the shaft side of the compressor, but I don't have a great understanding of the interior structure of the compressor.
Kitten juice
Originally Posted by slumlord
Kitten juice

I was going to post "pussy juice"...

John
I have bought cheap belts that do that.
Use Seafoam....

Spray it all in the engine compartment just as the sun is going down below the horizon ( important step on the insrtuctions in really fine print)
Coat the entire engine compartment...



Seafoam Mechanic in a can will find the problem ( and any others) your vehicle will be show room new๐Ÿ‘๐Ÿ‘๐Ÿ‘๐Ÿ‘๐Ÿ‘๐Ÿ‘ with a nice wax job by sunrise.

I schitt you not!!!



Seafoam

??


Thanks Mr Obvious, youre a lifesaver
Check the blinker fluid.
If the drive belt is at correct tension and has a bit of belt dressing applied, it will not make noise. A dying pulley bearing my give intermittent noise/squeal - the idler or the compressor in this case. Try using a stethoscope applied as closely as possible to the bearing housing to detect rumble/rattle indicating incipient failure.

I don't try to use a medical type scope in such cases - use one with a straight rod (someone makes/sells them) BUT the best for me is one I have made - a small can with a long rod through the bottom (thin welding rod?) - tip of rod on the moving part and can cupped to the ear. Easy to hear internal noises and bearing noise will be apparent..

If you heard the squeal from inside the vehicle, it could be a fan motor noise - including a squeal - sometimes happens only on start-up.
The idler pulleys I've had that went bad did not make a sound with the belt off, only with a load on them did they make noise. Compressor does have oil in it that could leak I suppose, but freon would leak also. I am in no way an automotive expert.
Originally Posted by Morewood
Check the blinker fluid.

Got some of the black stuff in my eye now I have plenty of blinker fluid...


Clutch dust is reddish brown. right?

Many it's just glopped clutch dust from having the a.c. on while going through the carwash...or maybe lizard guts.
Originally Posted by OldmanoftheSea
Originally Posted by Morewood
Check the blinker fluid.

Got some of the black stuff in my eye now I have plenty of blinker fluid...


Clutch dust is reddish brown. right?

Many it's just hopped clutch dust from having the a.c. on while going through the carwash...or maybe lizard guts.

Seafoam cleans ALL animal guts off automotive components.
That's in the fine print instructions too.
Never underestimate the fan clutch! They will be a different sounding more like a chirp in my experience ๐Ÿคทโ€โ™‚๏ธ
Originally Posted by MPat70
Never underestimate the fan clutch! They will be a different sounding more like a chirp in my experience ๐Ÿคทโ€โ™‚๏ธ

Got electric fans...
Doesnโ€™t the compressor pulley ride on a bearing when the compressor is not engaged? Couldnโ€™t that bearing go bad?
Anyone ever blow out a refrigerant seal from over pressure?

Say if the a.c. clutch didn't cycle due to a mugged up clutch?

I guess a failure of a weak spot in the condenser is more likely than blowing an o-ring...


There is at least some pressure on the low side
I just pressed the downside port stem to see if it hissed.
Which it did..
Buy a new truck.
Bad pulley or idler.
What year, make and model? Most ac systems have a high pressure blow off valve on the compressor, when the compressor builds to much pressure the valve will release it. If that's the case plan on spending some serious money.
high pressure isn't released by a 'blow off' since r-12. has an electric sensor that just cuts off the clutch. the stethoscope is a good idea. i just used a long extension. idler pulley the most common culprit.

btw, all a/c compressor seals leak a tiny bit. it lubes the seal.
Often the idler tensioner will begin to allow the idler to come out of square which causes the belt to "scrub" as it is moving.

It's not easy for the untrained eye to spot.
My idler pulley surface was so polished after 250,000+ miles it would squeal with a new belt. The new pulley was considerably more textured than the polished one. Problem solved.
The old belt was worn when I changed it.
I compared the grooves with a coin check and it was a significant difference.

Originally Posted by wahoo
high pressure isn't released by a 'blow off' since r-12. has an electric sensor that just cuts off the clutch. the stethoscope is a good idea. i just used a long extension. idler pulley the most common culprit.

btw, all a/c compressor seals leak a tiny bit. it lubes the seal.


A metal rod and an empty soup can make a pretty good substitute for a stethoscope..

Guess the electromagnetic clutch won't really "stick"...
Originally Posted by OldmanoftheSea
Truck made a strange noise at start-up the other day.
Similar to a belt squeal, but definitely different
I checked the belt, (even though it is new)

There was a glob of something on the surface of the idler pully which I cleaned off but that didn't cure it.

I noticed a black gummy substance at the boundary of the inner and outer portions of the AC compressor pully, so:
I turned off the a/c and restarted then the noise went away even after I turned the a.c. back on.

Any ideas?

Edit:
The a.c. clutch functions / stops if I pull the clutch relay fuse.
...............First off, I would do anything or have wrenches turned unless or until you have more frequency and consistency with the noise. If the noise gets more frequent, then that means you will be able to better figure out where and what the problem is......Sounds like it could be coming from your ac compressor clutch...If the noise does not come back with more frequency then I would not worry about it.
Originally Posted by OldmanoftheSea
Truck made a strange noise at start-up the other day.
Similar to a belt squeal, but definitely different
I checked the belt, (even though it is new)

There was a glob of something on the surface of the idler pully which I cleaned off but that didn't cure it.

I noticed a black gummy substance at the boundary of the inner and outer portions of the AC compressor pully, so:
I turned off the a/c and restarted then the noise went away even after I turned the a.c. back on.

Any ideas?

Edit:
The a.c. clutch functions / stops if I pull the clutch relay fuse.



Your clutch maybe working for now , but that black goop you found is the rubber/Plastic moulding around your armature for the clutch . Very common problem on ag / industrial equipment.
Get the numbers and make of your compressor and have it replaced. Hardest thing on ac clutch is not enough air flow thru the condenser, a lot of idling in hot weather will drive the high side pressure thru the roof.
Originally Posted by AbeJohnsen
Your clutch maybe working for now , but that black goop you found is the rubber/Plastic moulding around your armature for the clutch . Very common problem on ag / industrial equipment.
Get the numbers and make of your compressor and have it replaced. Hardest thing on ac clutch is not enough air flow thru the condenser, a lot of idling in hot weather will drive the high side pressure thru the roof.

I like this analysis - could explain a bunch of those symptoms, and probably the deal.
Thanks Bigsqueeze, Abe and CCC.C (sorry missed the fourth "C")
(And all previous contributors)

I think the noise was the compressor dying...

Went to the Brand new auto parts store and borrowed their manifold gauge set..
Think I was the first to use it...
Low side pressure up over 100psi.
High side just slightly higher so my assumption is the pressure is going back through the compressor which never cycles because it cannot reduce the low side pressure enough.

I don't think that the orifice valve opened up on its own!

I thin the worn belt probably contributed to the compressor failure and probably the battery (which I replaced right before the belt)..

The belt probably should have been replaced a year ago but the only sign of wear was the grooves had opened up a touch.

We will see what the new compressor does....
I also would check the cooling air supply to the condenser, as Abe noted.
Originally Posted by CCCC
I also would check the cooling air supply to the condenser, as Abe noted.

I checked the fans today and they both operate when the AC is switched on.
Maybe I should back flush the fins with some canned air?

Best of all the New unit is American made, came with all new seals and is recharged with lubricant.

God Bless Texas!
I bet that set you back several Benjamins. Nice to have it fixed though.
Originally Posted by gregintenn
I bet that set you back several Benjamins. Nice to have it fixed though.

Well not several, but a few..
I just hope that the bolts are not too stubborn.
Gotta prep them with pb-blaster....

I was trying to find the accumulator/dryer, apparently it is stashed next to the condenser...

Gotta love dealerships that make their parts diagrams available....
I just love replacing things that were installed on the lower quarter of the motor before the motor was installed....
At least they made a little room to work...
But I think they assumed people would be using an air ratchet....

But I learned why mechanics never make any money..I was looking for a 1/2" drive 10mm socket..
I had to go through the Snap-on guy who I just happened to pass on my way back from the hardware store..
Wow..
And of course my breaker bar still barely gave me enough room to get the socket on the banjo bolt head...

On the bright side, it went back together way easier than it came apart ...
So the isolator is cooked...
And the air gap is effectively zero (can't get a .002 in)

I also see some scoring on the edge of the eccentric lobe..
But it still compresses and draws..
Although it occasionally drags like there is material in there.

Assuming the clutch failed and spun the compressor until it didn't have sufficient oil.

Any DIY tricks to hold the clutch still?
I wanted to pull it and inspect the compressor face before i recharge the system..
It's got three little buttons on the face of the plate, they protrude 2-3mm from the face plate, but the plate is recessed below the isolator..

And I just realized I had a 10 mm for one of those huskey open center sockets that would have worked on that banjo bolt...
I guess you can never have enough 10mm sockets...
didn't the new compressor come with the clutch installed? the air gap shouldn't be that small. the clutch wasn't engaged, was it.
Originally Posted by wahoo
didn't the new compressor come with the clutch installed? the air gap shouldn't be that small. the clutch wasn't engaged, was it.


It did..
Spec is .014-.026

But trying to get my head clear that there is no chance of a bad orifice...

Since the low side pressure was up over 100psi
And it seems unlikely that backflow occured thorough the compressor.

I guess it would help to know what the expected equalized pressure across the system should be..
the high low side, low high side usually means the valves in the compressor are compromised and the system is equalized. you may get some cooling, but not when the system has a high heat load.
Ah
Here we go..
https://ricksfreeautorepairadvice.com/ac-pressure-gauge-readings/

I guess that 100+
PSI is fairly normal if the clutch is failed and the system is in a quasi-static state...

From trying to pull the clutch I see that:
The pully will spin,
The isolator will spin
And the faceplate/ shaft will spin by turning the shaft attachment screw..
One too many degrees of freedom
So the burnt rubber smell (which I previously failed to mention) wasn't the belt, it was the isolator cooking and likely the cause of the rasberry-ish sound which I was thinking might be the orifice valve failing....
you replaced the orifice valve too, i hope. if it wasn't clogged, it had some stuff in it.
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