Compressor has started screaming

[CountOnIt]

Hey guys,

I have a USS 8 64.  You guys helped me a lot with a thermostat problem I was having a few weeks ago and I thought I was almost done.  Of course that would be too easy.  I plugged it back in over the weekend and I thought everything was working right, but then the compressor started screaming.  The longer it runs, the louder it gets.  I had my HVAC guys come out and take a look.  It has the proper amount of refrigarant and everything is working as it should.  He said that the compressor is probably about to go, but it may not go for 5 days or 5 years.  I was talking to a friend and he asked if I had checked to see if there was any way to put compressor oil in it that may quiet it back down.  I've been running it for a couple of months now and this weekend is the first time it's every done this.  It still cools everything down great, but you can actually hear it in the house now it's so loud.  I have it in the garage. 
Here's what I'm wondering.  Can you actually put an oil in it that will quiet it down?  And if it's on it's way out, what should I expect to pay for a new one?  As usual, thanks for all of the help in advance.

-Chris

[MrMark]

Compressors like are used on these boxes don't "scream". Condenser and evaporator fan motors do.

I wouldn't trust your HVAC guys if they didn't know 1) these compressors don't "scream" and 2)a fully hermetic system that has lost enough oil to cause a system to "scream" is a system that leaks refrigerant.

Condenser and evaporator fan motors are easy to replace. I just bought 1 of each for both of my coolers.

[CountOnIt]

Well it's definitely the compressor.  I unplugged the compressor and the fans were still running and it was quiet.  Plugged the compressor in and within 2 minutes it was loud again.  I ordered another compressor for it.  The price wasn't quite as bad as I thought.  I also ordered a new filter dryer.  I know my HVAC guys did check to make sure it was full and I was right there when they had their guages hooked up.  I'm thinking the piston or bearing is just finally giving out.  I'm not thrilled about all of the money I'm sinking into this thing, but I'm hoping this will be the last major problem I have with it.  We'll see........  Thanks for the reply.

[MrMark]

CountOnIt,

Your there and I'm not, so if it's the compressor, so be it. I sure would like to hear the sound though. In over 40 years of being around HVAC, I've never heard a "screaming" compressor.

And the way most of these boxes are made, you can't unplug the compressor apart from the other components. You can unplug the condenser fan though (and it's the condenser fan that is the more likely candidate to "scream").

As for your HVAC guys checking the refrigerant with their gauges, these units are sealed systems that do not have permanent gauge taps on them. If they put "Tap-A-Charge"'s on the unit to check refrigerant, there is no way to remove them without losing the charge. And per EPA, they are not to be left on an operating system as they leak, especially R12.

What compressor did you buy, and where from? Are you going back with R12?

[CountOnIt]

The way it worked for me was that I would turn the thermostat to off and I could still here the fans running.  They were quiet as a mouse.  Also, when I turned off the compressor it would let out this high squeal as it shut down.  The fans kept running and didn't have a problem.  For whatever reason, my compressor had already been tapped, which my HVAC guys said mean that it must have had a leak at some point, because they said the same thing you did.  It is supposed to be a sealed unit. 
I ordered this:

TECUMSEH COMPRESSORS
Comp 115V 1/4HP R12 1PH Hi

I orderd it from Buildinghvac.com  I also ordered a new Filter Dryer.  I really hope I'm not missing something here, but I am 99% sure it's the compressor.  I don't know much about HVAC, but I do know things like when it's gargling it usually is low on freon.  I didn't hear it gargling or anything like that.  And I wish I could take a sound clip and send it to you, but when my buddy said put the phone up to it so I can hear it he couldn't hear anything.  I think the frequency is just too high.  Does all of this sound like I'm on the right track to you?

[MrMark]

Well,

The condenser fan cycles with the compressor, so if it was running, and the compressor wasn't, then I guess it was the compressor.

I am just thinking out loud here, did you ever put your hand on the compressor and apply a little pressure while it was running and make sure it wasn't the compressor mounting that wasn't screaming? Same with the condenser fan? If the sound was a high pitched schrill, then it could be the mounts have dried out like they do on a car chassis and start squeaking. But anything inside the compressor that could cause a high frequency pitched sound would tend to remain in the compressor dome, and be somewhat muted by the dome itself. The compressor is turning either 1800 or 3600 rpm, and they will usually seize up before the bearings get dry enough to start squealing (I've cut working compressors open for demonstration of how hard it is is to get liquid refrigeration to the suction valves in a hermetic compressor. They don't run long before they begin to seize and burn up the windings.).

Since the box had a leak, it has likely lost oil. But again, oil loss usually equates to compressor seizing, not squealing or squealing then seizing.

And I don't want to put doubt in her actions or experience either. I as just being hard to convince that the squeal is coming from inside the compressor.

Which R12 Tecumseh did you get? 1/6, 1/5, 1/4, 1/3 HP? Low, medium, or high pressure? The HVAC guys really need to find the leak if you drop a new compressor in the deck.

[CountOnIt]

We put pressure all over the compressor trying to get it to quiet down, but I don't think it was the mounts.  It's funny, I'm in the car business so I actually did mention that sometimes engine mounts will go out and cause all kind of noise.  In this case I really think the compressor is just done.  I actually think it's the original compressor and it doesn't appear that it was taken very good care of.  I don't think there's a leak anymore, but the taps proved that there had been one at some point during its life. 
I got the 1/4 horsepower hi pressure.  I talked to Sharon at Soda Jerk Works and she gave me the exact part number to order.  Those guys are amazing!

[MrMark]

CountOnIt,

Yeah, SodaJerk Works is/are good! As is Eric at GlobalCompressors.

Interesting on that squeal.

Be sure to take the service taps off the unit when you get her going again. At most, all you need is a suction stinger to evacuate and charge the system. Some say it will evacuate faster to pull from suction and high side, and they are right, but the fewer taps are on the system, the less of a chance for a leak in the future. You pinch off the the stinger, cut and silfos seal the stinger when you are happy with the charge. Be sure to weigh it in as per the data label on the deck or the unit. If 1/4 HP, I am thinking 12 oz, but check to be sure.

Good luck! And let me know what you find.