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Drcool, HVAC Technician
Category: HVAC
Satisfied Customers: 2086
Experience:  i have been an A/C tech for the past 12 Years. working on window types, split type, and package
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HVAC repair, part 2: outdoor condenser fan stops running

Resolved Question:

1) I need someone to confirm the specifications for a  dual capacitor that should be installed in the outdoor condenser unit of a Amana Prestige RCE60C2A . I want you to check the literature. I'll explain in a bit.


2) I need to figure out why the outdoor fan on the condensor unit stops running after a few minutes of operation, and won't restart with the "pencil/stick" trick. I've already examined a variety of things.



Two months ago HVAC tech replaced my first capacitor in my Amana Prestige RCE60C2A with a  80+5 MFD capacitor. A week ago my AC stopped working: the compressor would not start. I checked the capacitance of the installed capacitor and determined it had failed. I was advised on JustAnswer to replace this capacitor with a 40 + 7.5 MFD capacitor. 


I installed the 40+7.5 MFD capacitor today. The compressor started up and the house started to cool. The issue now is that after a few minutes of operation the outdoor fan stops running, eventually the compressor sounds labored, and it shuts off, probably to protect itself.  As a test I attempted to restart the fan while the unit was still on by prodding the fan blades with a stick. The fan blades run smoothly but the fan will not start.


The HVAC tech's capacitor was 80 +5 MFD. The new capacitor is 40+7.5. I am wondering if it is possible the fan capacitor is supplying too much power, overheating the fan and causing the fan's thermal protection to kick in. This is why I want an authoritative answer for what the correct capacitor rating is for my unit.


If the capacitor isn't the issue, I would like to figure out what is wrong. The fan seems to run correctly while it is running.


I went into the attic and very carefully cleaned the fins around the evaporator coils on the indoor unit. They were not particularly dirty and I don't think this was the problem. 


Filters have been replaced and are clean. The system is about 6 years old.

Submitted: 3 years ago.
Category: HVAC
Expert:  Drcool replied 3 years ago.

Drcool :

Hello, Do you have a current meter so that you can measure the current the compressor and the fan is drawing? I am assuming you have a 5 ton single phase unit that is why an 80 MFD capacitor was installed by the first tech and it lasted 2 months. And the fan capacitor was 5 MFD.

Drcool :

Now, after 2 months, you were able to check that the 80+5 MFD failed and was advised to replace it with a 40+7.5.

Drcool :

Now the fan is quitting after a few minutes. My theory is the fan is drawing too much current because the capacitor increased from 5 to 7.5 MFD. That is why you would need a current clamp meter so you can know what are the actual current the fan motor is drawing. I would suggest that you replace again the 7.5 MFD capacitor with a 5 MFD capacitor. I am just worried about the 80 which was reduced to 40.

Drcool :

For me, I would say 40 is a little bit low for a 5 Ton unit and I would only put a 40 MFD to a 3 ton unit. Even though the compressor did run, I would suggest that you replace the capacitor back with the 80+5 MFD then take the current draws of the components and we can observe and discuss further what could be done based on the current readings.

Drcool :

I suggest also that you clean the condenser coil. A dirty condenser would contribute for the capacitor to fail.

Customer: replied 3 years ago.
I was hoping somone could actually look up the requirements in whatever literature is available to HVAC techs. I do have a autoranging multitester, though I don't have a clamp meter. I could probably buy one if it would help us figure this out. I also have some information from the literature I did find that might be useful. Here are some stats for my unit:

Cooling capacity, BTUH: 60,000
Compressor: R.L. Amps: 25
Compressor L.R Amps: 169
Condensor Fan Motor: 1/4 horsepower
R.L. Amps: 1.7
L.R. Amps: 3.3.
Power supply: 208/230-60-1
Minimum Circuit Apacity: 33.40
Maximum Circuit Ampacity: 55

Does this help? Is there further diagnostic work I could do with my multitester?
Expert:  Drcool replied 3 years ago.

I have seen those infos that you gave. Yup, it did not say what size of capacitor your unit is using but based from my experienced, a 1/4 HP fan motor really uses a 5 MFD capacitor only.

Then the 40 MFD capacitor for the compressor is only for a 3 toner unit whereas you got a 5 toner.

Sorry If I do not have the exact literature where it would tell what capacitor to use.

It would really help us if you would have a clamp meter so that we can compare to the rated current that you have.
I am sure the fan motor current would be more than 1.7 amps running current of the fan.

Thank you

Customer: replied 3 years ago.
OK. I will buy a clamp meter in an hour or two. I will write you back when I have it. Should my clamp meter have any special features, or will either of these do?:
Expert:  Drcool replied 3 years ago.

I was not able to see the other one but the first one would do it.

Just set it to measure ac amperes and clamp the meter to the common wire of the compressor or to the running wire of the compressor.

Customer: replied 3 years ago.
Will I need to open the housing to the fan so I can get physical access to the compressor, or will I be able to work off of the wires coming to and from the capacitor? There was a red wire and a black wire connecting to the "C" terminal of my capacitor.
Expert:  Drcool replied 3 years ago.

You can clamp the meter from the magnetic contactor of the unit.

The compressor common wire would be connected at the load side of the contactor.

It would be the bottom part if the contactor is mounted vertically.

Post what current you would find out on each wire connected at the bottom of the magnetic contactor.
Be careful, you would be working near a live wire.
Be sure all screws are tight because you would be pulling wires as you try to clamp the meter on them.


Customer: replied 3 years ago.
Here is a link to photographs of the inside of my HVAC unit, including the contactor:

Do you mean I should measure the black wire and the gray wire at the bottom of the contactor?

I have ordered a new 80+5 capacitor. It will be delivered tomorrow. Should I go ahead and make the electrical measurements using the capacitor I have in place now (40 + 7.5) or should I wait for the new capacitor?
Expert:  Drcool replied 3 years ago.
If the black wire and the gray wire both went to the compressor , then yes you can measure the current passing through them one at a time. But if the wires came from the power box, then that would be the line side of the contactor and the violet and pink ( as I see them on the pictures) are the load side of the contactor. Then these wires are the wire that you would take measurements later.

Clamp the meter on each wire and measure the current.

I suggest you wait for the 80+5 so that the fan motor would not be subjected to high current anymore.

Customer: replied 3 years ago.
OK, I found a local supplier for the 80 +5. I'll pick that up and the multimeter up now.
Customer: replied 3 years ago.
Actually I'm going to be waiting until early afternoon for this pickup. If you're around this afternoon/evening, great, if not we can work on this when you're available. Hopefully the 80+5 will resolve the problem and the remainder of your answer can simply be to train me how to use the clip-on meter and interpret what results we get from it. thanks!
Expert:  Drcool replied 3 years ago.
You are very much welcome.

Hopefully, you would have this resolve after replacing the capacitor.

Thank you too.

Customer: replied 3 years ago.

Good news: the 80 + 5 capacitor solved the problem! My system has been running for 2 days with no troubles.

If you can tell me how to use the clamp meter I would appreciate it. At this link is a picture of the meter, including a close-up picture of the dial:

Please tell me what setting I should have the clamp meter's dial on. When I take readings, I can take them while the AC unit is running, correct? And I should have the wire running inside the clamp, is that correct? What will the reading I get from the meter tell me about the required capacitor?

Also, looking at the photos, can you tell me what kind of contactor my system has? Looking at this link, can you tell me which one I would buy so I can have an extra contactor to use as a replacement if necessary?:

Please tell me these things and I will pay you and tip you, thanks!
Expert:  Drcool replied 3 years ago.

Glad to hear that your unit is up and running again.

To use the clamp meter, set the dial to the left side of the off position. That is the ac amperes which has two ranges. 200 amps and 1000 amps. Use the 200 amps so you can get a more accurate reading.

To use it, clamp one wire from the magnetic contactor load side to the compressor. Either of the wires would read the same.

Then do the same for the wires going to the fan motor.
Then compare these reading with the RLA rating on the name plate of the fan motor as well as on the manual of the unit or on the nameplate of the condensing unit as well.

RLA means running load ampere. That would be the rated current the unit should draw when ever it is running normally.

If the reading that you will get is lower than the rated, then nothing to worry about. What you would worry is if the reading are above the rated. It could happen if the ambient is very hot but it should be temporary.
If the reading goes above 30 percent of the rated current, then try to check something because this is no longer normal.

Regarding the contactor, verify the coil voltage first of your unit.
I am assuming you still got the 24 volts system so you would order the 30 ampere double pole 24 volts coil but I have no history record of your unit so we do not know if it has been modified to use 120 volts coil.

To verify coil voltage, while the unit is running, set your clamp meter 4 clicks to the left. This would point to the 1000 volts ac. Then plug the test probes to its respective slots, black to black and red to red. Then put the probes to the small wires at the side of the magnetic contactor to measure the coil voltage while the unit is running. JUST BE VERY CAREFUL ON DOING IT SINCE YOU WILL BE NEAR LIVE VOLTAGES.

If you read 24, then order the double pole, 40 amps 24 v coil

Regarding the required capacitor, I think 80+5 is the best for your unit.

-Thank you very much for using this service.

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