Ruud AC

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  #1  
Old 05-30-18, 10:14 AM
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Ruud AC

Ruud AC 14AJM49A01 was installed 4 years ago (2014). We were away for a 3-week vacation on May 2nd and set the thermostat at 88 since nobody would be home. Returned home on May 24th with temperature at 85 in the house, set the thermostat temperature lower to 79, and heard the fan in the house running and realized after a few hours it was not blowing out cold air.

Checked the filter and found it was completely blocked. After replacing the filter, fan in the house still not blowing cold air. Went out to check the unit, found out the fan is not running and little humming sound coming from the unit, presumably from the compressor. Gave the fan a little push, but fan is not turning at all.

Shut off the AC and turned on again after a few minutes. As soon as it turns on, a loud sound came from the unit (compressor?) with the fan not turning, after a minute the sound stops and become a little humming noise with the fan still not turning.

Thinking of replacing the capacitor. After opening the cover found out there is only one capacitor with two terminals on it and it could very well be the run capacitor for the compressor with ratings 45mfd/370V (43-101666-37)and didn't see any other start capacitor nearby. The question is why is there NO start capacitor for the outside fan? Is it possible to have the no such start capacitor? How would the outside fan motor run without capacitor?

There might have been a few days during the 3-week vacation period with high temperature that caused the AC to turn on the whole time with the outside fan already not running.

Still waiting for the run capacitor 45mfd/370V I ordered.

Any helpful suggestions would be greatly appreciated.
 
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  #2  
Old 05-30-18, 11:26 AM
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You're correct, the 45mfd capacitor is almost certainly for the compressor. The only reason I can think of why there is no capacitor for the fan is that Rudd possibly used an ECM (Electronically Commutated Motor). These motors are usually used for blower motors because their speed is continuously variable and they are more energy efficient.

There should be a wiring diagram inside the outside unit, often on the removable cover. If you find the diagram, take a picture of it and post it here. The wiring diagram will show whether what type of fan motor is used and whether it uses a capacitor or not.
 
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Old 05-30-18, 11:36 AM
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I found a wiring diagram online for the Rudd 14AJM49A01 condenser unit. It shows a standard PSC motor using a 3 terminal dual capacitor.

However, I also found an alternate wiring diagram that shows the use of an ECM fan motor. Since you only have a single capacitor, I assume that you have an ECM fan motor.
 

Last edited by Bob14525; 05-30-18 at 11:43 AM. Reason: Update
  #4  
Old 05-30-18, 12:17 PM
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Thanks Bob14525 for your prompt response. Did the clogged/blocked air filter somehow overheated the system and burned any of the motors - outside fan and/or compressor? Would replacing the compressor capacitor 45mfd/370V fix the problem and make the OFM run? What should be done next then?
 
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Old 05-30-18, 01:11 PM
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It's unlikely that the dirty air filter damaged the condenser fan motor. There has been a common problem with the ECM blower motors (mine failed after almost 5 years). I don't know if the problem with the ECM blower motors exists in the ECM fan motor. The ECM blower motors use a thermistor in the power circuit to limit the inrush current. Here's a link to a thread discussing the problem with the blower motors:
https://www.doityourself.com/forum/a...placement.html
As I see it, you have 2 options for repair. One is to pay a technician to diagnose whether the motor is bad. If it is, there's a possibility that it may be covered under warranty (the ECM blower motor is ~$1000). The second option is to remove the motor, remove the control module from the back of the motor (assuming it's similar to the blower motor), and check for a burned thermistor. If it is, you can replace it if you have basic soldering skills.
 
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Old 05-30-18, 02:51 PM
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Thanks Bob14525 .

Sounds like the problem is not with the run capacitor 45mfd/370V then and is a more serious one.

But in any ways, I'll replace the run capacitor first when it arrives and just hope it would work.

Thanks again.
 
  #7  
Old 06-01-18, 11:51 AM
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The system has been turned off for 4 days since Monday, May 29, 2018. Temperature of the Honeywell thermostat reads 77 degree today, Friday, June 1, 2018 and I turned on the inside fan , it starts running and air is coming out from all the vents, after half an hour the fan is still running but air is NOT coming out from the vents anymore, so I shut off the fan. After half an hour, I turned the fan on again, it is running but this time air is NOT coming out from the vents from the start.

What is happening?
 
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Old 06-01-18, 12:21 PM
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If I understand you correctly, the system sat idle for 4 days. Then you turned on just the fan (blower) and you had normal airflow coming out of the vents. Approximately 30 minutes after turning on the A/C, the airflow coming out of the vents was greatly reduced. This is what I expected. The evaporator coil is frozen up again, blocking the airflow.

There are two common reasons for the evaporator coil to freeze up: restricted airflow because of a dirty air filter, or the system is low on refrigerant. Since the air filter was originally dirty but has been replaced and the system is still freezing up, then you are very likely low on refrigerant due to a leak somewhere in the system. At this point, you'll have to call an A/C tech to come out and try to find the leak and recharge the system.
 
  #9  
Old 06-01-18, 01:06 PM
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No, A/C was never turned on and the system was OFF all the time.

I just turned on the inside fan to check if it is working. AT first the fan was running and had normal airflow coming out from the vents, half an hour later, the fan was still running but NO air (or maybe very very little air) is coming out from the vents then I turned off the fan.

After half an hour I turned on the fan again (with the system still OFF), the fan is running and this time no more (or maybe very very little) airflow coming out from the vents.

The system would still freeze up after 4 days?

The run capacitor (compressor) I ordered has not arrived yet.

Thanks Bob14525.
 
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Old 06-01-18, 01:13 PM
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It's very important that you have normal airflow through the air handler. If, for any reason, the airflow is significantly reduced, the evaporator coil will freeze up. I'm sorry that I misunderstood what you said earlier. Given the information, it appears that you have an issue with the blower in your furnace/air handler. Depending upon the type of blower motor used, the blower motor may use a capacitor.

What is odd is that I understood you to originally say that the fan in the outside unit (condenser/compressor) wasn't turning. It's odd that both of your fan motors (inside & outside) are having problems.
 
  #11  
Old 06-01-18, 01:37 PM
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Sorry for the confusion.

When for the first time after 4 days I turned the "Fan" on the thermostat to ON with the System OFF, I can hear the fan running inside the house, and there is normal airflow from all the vents but after half an hour no more air (or maybe very slight air) is coming out from all the vents. Then I turned the "fan" on the thermostat to "auto.". After a while I turned it on again (with the system still OFF) the inside fan is running but no more air (or very slight air) is coming out from the vents.

Guess I have a big problem here.
 
  #12  
Old 06-01-18, 02:47 PM
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You have an odd problem. When you turned the blower back on the second time (Fan switch set to ON), you said that the inside fan (blower) is running however you're getting very little airflow. How do you know that the blower is running, can you hear it? If so, does it sound like it's running at normal speed? I can't figure out why the airflow would get greatly reduced unless: a) the blower is significantly slowing down, or b) there's a blockage in the air path.

The thought just occurred to me, does your blower (squirrel cage) connect to the motor via a belt, or is it direct drive? If it uses a belt, it's possible that the belt is slipping (unlikely, but possible).
 
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Old 06-01-18, 06:28 PM
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Thank you for your valuable advise.
I should have an A/C technician check them out and give you an update.
 
  #14  
Old 06-08-18, 04:23 AM
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The technician came yesterday afternoon and he said the culprit is the fan motor, as it's a computer controlled motor. Warranty for parts is 5 years, he will replace it with the "old fashion" non computer controlled one. He will get it in a couple of days. Let's see.
*****************************
The 45mfd/370V capacitor I ordered came yesterday morning, I replaced it, the result is the same as before:

When the A/C is turned on, the compressor and fan started to run. The fan run fast, quietly and smoothly, for a few turns and stopped completely. The compressor run with a loud noise (the normal sound?) for about 4 minutes and then there was a "pssst" sound and the noise became weaker, after another 4 minutes it stopped running.
 
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Old 06-08-18, 02:55 PM
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The technician came to replace the fan motor with Protech 51-23053-21, 1/6-1/3 HP 1075 RPM Motor (208-230V), the A/C is working fine for now.
 
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