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Posted: 4/14/2017 10:27:51 PM EDT
i just heard the damndest sound from the outside half of the house A/C system. 

nothing, nothing, nothing, rumble, crashety rattle crunch rattle, nothing, nothing....

The house A/C is on, and there is cool air coming through the vents.
The fan on the external unit is not turning.
The fan will spin easily if you move it manually.
No obstructions are visible inside the unit, though its hard to tell with the big fan blades in the way.

What diagnostic tests can I do with a screwdriver, flashlight and multimeter?

Any thoughts on what the root cause might be?
Starter Capacitor?
Flux Capacitor?
??
Link Posted: 4/14/2017 10:31:36 PM EDT
Your motor on the condenser (outside) may have gone out.

How old is the unit?
Link Posted: 4/14/2017 10:32:24 PM EDT
Try hitting the fan bearings with something like Tri-Flow or another good lubricant.
Link Posted: 4/14/2017 10:32:42 PM EDT
Doubletap
Link Posted: 4/14/2017 10:34:26 PM EDT
Start with the capacitor/s. need to be within 6% of the rated mF.

If those are good and the compressor is running then it's likely the motor. Make sure the capacitor/s are replaced at the same time.
Link Posted: 4/14/2017 10:36:22 PM EDT
Either motor died or bearings died. Either which way time for new motor.
Link Posted: 4/14/2017 10:36:34 PM EDT
It's about an 8 year old York.
There is no noise when I spin the fan blades by hand, and they turn freely.
The noise seems to be coming from the bottom of the unit.
Link Posted: 4/14/2017 10:40:39 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
It's about an 8 year old York.
There is no noise when I spin the fan blades by hand, and they turn freely.
The noise seems to be coming from the bottom of the unit.
View Quote
Is the unit still making noise while the fan blade is not moving?
Link Posted: 4/14/2017 10:56:23 PM EDT
The fan blade is not spinning.
There is a subdued noise from the unit.
Every so often, the noise starts & the unit rattles a bit, then the noise stops.
Its quiet-ish for a while, then it starts making the noise again. 

I'm familiar with discharging CRT voltage. What is the safe procedure to discharge a start/run cap with three connections?
Link Posted: 4/14/2017 10:57:15 PM EDT
Motor or capacitor.
Link Posted: 4/14/2017 11:00:48 PM EDT
turn it off and a tech
Link Posted: 4/14/2017 11:02:52 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The fan blade is not spinning.
There is a subdued noise from the unit.
Every so often, the noise starts & the unit rattles a bit, then the noise stops.
Its quiet-ish for a while, then it starts making the noise again. 

I'm familiar with discharging CRT voltage. What is the safe procedure to discharge a start/run cap with three connections?
View Quote
May have an internal thermal fuse that is shutting down the motor if the cap is dead. My tester discharges caps as you test them in the mF test mode or you can carefully unhook the leads after killing power and short them to each other with a screwdriver or other insulated tool.
Link Posted: 4/14/2017 11:18:58 PM EDT
I lived in central FL without a/c for 3 years and I worked nights... toughen up.
Link Posted: 4/14/2017 11:24:17 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The fan blade is not spinning.
There is a subdued noise from the unit.
Every so often, the noise starts & the unit rattles a bit, then the noise stops.
Its quiet-ish for a while, then it starts making the noise again. 

I'm familiar with discharging CRT voltage. What is the safe procedure to discharge a start/run cap with three connections?
View Quote
If the compressor is still running you should be able to hear it, if so it could be building up pressure and then releasing it some how but I doubt that. Depending on the size of your unit The capacitor is probably a 35/5. 5 being for the fan cut the power, take the service panel off mark where the wires go on the cap, there will be a C for common, herm for the compressor and F for the fan. Take the wires off and discharge it by touching a screwdriver to the terminals, then take a multi meter set to ohms and touch one lead to the C and the other to F the needle should go up and back down each time you do this you have too switch terminals also touch one lead to the case and one to each terminal if you get continuity it is shorted. As said above if your meter will check microfareds check that too.

ETA: The fan will have a thermal overload, if it overheats it will shut off till it cools down if it is doing that it is most likely the cap, if not the cap then the fan is bad of course.
Link Posted: 4/14/2017 11:47:46 PM EDT
The compressor is in the bottom of the unit.  Does it still make the awful sound every so often while you are watching it or was the noise a one time deal?
Link Posted: 4/15/2017 1:10:38 AM EDT
Ok op, so there is some good advice and some not so good advice being given...


If the condensor unit is making noise but the fan is not turning, that means the compressor is running, but no fan. This would lead me to believe its a start/run capacitor.

So, kill power via disconnect, open access panel, (should be 1/4" screws, where the power conduit runs in,) and find the capacitor. Pull the three wires off, noting where/what color wires go to what terminal, and test for microfarads. IIRC should be +-about 5.) If its not in spec, change it. If it is in spec, its probably the fan motor.  If you change the fan motor, change the cap too.

What you should do right now is kill the whole system. Your compressor is probably running right now and overheating. They do have a thermal overload, if it hasnt tripped by now i guarantee you that bitch is running way hot.


Also, sorry to tell you, but your york system is builder grade and is a complete pos. When its time to change it, change both the air handler and condensor, buy an American Standard. Use a reputable company. Google reviews your friend.
Link Posted: 4/15/2017 9:34:06 AM EDT
Yep - I expected it was complete builder grade junk. 
And yep - we turned it off as soon as the failure was identified. There might have been cool air coming from the vents, but nothing good could possibly come from the noises being made to get it.

There are some good troubleshooting ideas shared in this thread. Luckily I am not allergic to poking about in household voltage items. Once I get back from the veterinarian with the boys I'll be putting these suggestions to work.
Link Posted: 4/15/2017 4:00:11 PM EDT
I have the capacitor pulled.
Assuming the production code contains the manufacture date, it was made 5-13-93.
4.0/35.0, 370VAC
York part 024-23297
AmRad part R2000/37 (405+356)

No shorts from any contact to the case.
Common to each (Fan, Compressor) starts with low/no resistance then resistance slowly grows.
It turns out my cheap MM doesn't have capacitance measurements. Looking for one that does.
Link Posted: 4/15/2017 4:16:29 PM EDT
The most important question.  Why does Amish Bill have air conditioning?
Link Posted: 4/15/2017 10:58:44 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The fan blade is not spinning.
There is a subdued noise from the unit.
Every so often, the noise starts & the unit rattles a bit, then the noise stops.
Its quiet-ish for a while, then it starts making the noise again. 

I'm familiar with discharging CRT voltage. What is the safe procedure to discharge a start/run cap with three connections?
View Quote
The humm is the contactor from your thermostat engaging.
Link Posted: 4/15/2017 11:12:02 PM EDT
I have two condenser units and live in the woods.
Almost every spring at least one condenser is down. Its usually mice.
They love to chew the t-stat wire which is low voltage hot at ll times.
Next most common damage is a  capacitor. The rodents love to build their nest on top of the capacitor. First time I power up the unit- POP. most of the time its fried mouse, sometimes it takes the  capacitor with it.
I've sealed every crack and hole and yet they still manage to find a way in.
Link Posted: 4/15/2017 11:16:12 PM EDT
Link Posted: 4/15/2017 11:21:00 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
It's about an 8 year old York.
There is no noise when I spin the fan blades by hand, and they turn freely.
The noise seems to be coming from the bottom of the unit.
View Quote
If the outside fan isn't running turn the unit off And have it looked at by a hvac tech.
Link Posted: 4/15/2017 11:30:36 PM EDT
You need someone who knows what they are doing.  Get a reputable company if you don't know anyone.

You could have a bad contactor not passing voltage correctly through to the fan and compressor. It that power is not right it will kill your motors fan and compressor get someone out there who knows what they're doing
Link Posted: 4/15/2017 11:39:51 PM EDT
I just read a little more. Sounds like the compressor is tripping on high head pressure because the fan or fan capacitor is out. The rattling is herd is likely the compressor valves as it shuts off on high head.
Link Posted: 4/15/2017 11:41:29 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
It's about an 8 year old York.
There is no noise when I spin the fan blades by hand, and they turn freely.
The noise seems to be coming from the bottom of the unit.
View Quote
The noise is your compressor over heating.  

Fan motor is dead. Shut it off before it gets expensive.

ETA, if you want to DIY, you can figure out the voltage the motor runs at, turn the unit back on, and check for that voltage on the leads to the fan motor to ensure that it's getting voltage and not a problem at the control card. There's likely a relay on the card and that could be the failure too.

But IME, it's the fan motor. YMMV.
Link Posted: 4/15/2017 11:46:20 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I lived in central FL without a/c for 3 years and I worked nights... toughen up.
View Quote
You are the definition of tough.
Link Posted: 4/16/2017 8:32:58 AM EDT
Awesome thread, good luck to OP.
Link Posted: 4/16/2017 12:02:38 PM EDT
Root Cause Failure Anayliys:
24 year old capacitor in a 24 year old external heat pump / AC unit failed. 

Resolution:
Local Arfcommers helped OP get a suitable substitute - after hours - on a holiday weekend.
(Thanks John, Robpiat)
Link Posted: 4/16/2017 6:46:33 PM EDT
Excellent! Always look at the cheap parts before spending $$$$ on the expensive one's.
Link Posted: 4/16/2017 6:48:50 PM EDT
Had that happen to me, ordered a new motor from Grainger.  Replaced it and the capacitor while I was at it.
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