Ruud Outside Unit Fan Spins then Stops - No Cold Air

[gramsay]

Hello,

I am new to this forum in search of info that can help me with
a recent AC problem.

I bought my house with the AC as is in 2005 and I had it serviced when I moved in. This is the first problem I've had since 2005.

I have a split unit and the problem is with the outside unit.

RUUD Achiever 10 SEER AC

Compressor Copeland Compliant Scroll
Model# ZR36K3-PFV-230
Serial# 00FZZ418T

RUUD Air Conditioner 09/00
Model# UAKA-037JAZ
Serial# 5429 M4300 07527

The fan does not spin and hence no cold air.

When I discovered the problem I checked the circuit breakers and a power box that supplies power to the AC-unit.
I confirmed there is power going to the AC-unit.

I turned on the T-stat and then the fan spun then it stuck and did not spin. I was able to manually spin the AC-unit CCW with no restriction.

The fan did not turn on as usual.
----------------------------------------------
Next day:

Test AC.

T-stat @ 85

Turn on T-stat and set to 78

check fan, outside, its spinning ok.

AC is cool, but could be cooler.

Two(2) hours later, check fan.

Fan is not spinning.
AC is not cool ...

try to shove fan CCW as before,
Able to manually spin the fan, with no restrictions.

Fan does not spin on its own.

AC is not ok.

----------------------------------------------
Next day:

Test AC.

T-stat @ 85

Turn on T-stat and set to 78

check fan, outside, its spinning ok.

AC is cool, but could be cooler.

AC is ok.

check fan (1) hour later

Fan is not spinning.

Hear a hum near fan.
Then hum goes away within a minute

try to shove fan CCW as before,
Able to manually spin the fan, with no restrictions.

Fan does not spin on its own.

AC is not ok.
-----------------------------------------------------

From reading this forum it seems the problem could be the fan-motor or the capacitor or etc.

Any suggestions or opinions are greatly appreciated.

Peace,
GR

[Houston204]

If the fan spins freel with power removed, replace the capacitor. Match the microfarad and voltage.

[jim-connor]

Stop running the system until it is repaired. Doing so may turn an easy fix into a compressor replacement (expensive).

[gramsay]

Originally Posted by jim-connor

Stop running the system until it is repaired. Doing so may turn an easy fix into a compressor replacement (expensive).

Hello Jim,

The AC is off.

As it turned out, I was blessed that when the AC broke[fan] the weather temperature was 90 and two (2) days later the temperature dropped to 67.

No need for AC.

Peace,
GR

[gramsay]

Originally Posted by Houston204

If the fan spins freel with power removed, replace the capacitor. Match the microfarad and voltage.

Hello Houston,

Thanks for the reply and info.

I've done some research on my problem and Im trying to understand why the capacitors would be the problem.

Im not familiar with AC units, AC motors and AC capacitors.

But typically a bad capacitor is either an open or a short.
The open is the worst condition and no voltage would go to the fan.

In my case there is power to the fan, but it doesnt spin.
So, I think the fan motor is bad.

I did an experiment by disconnecting the AC Compressor and both capacitors.

Leaving just power and the fan.

There was power to the fan (hum).
The fan moved a bit then stopped like there was a restriction.

I removed power and the fan did spin freely.

Is the fan bad ?

Thanks ...

Peace,
GR

[Houston204]

Ohm out your motor.

1. Measure common (black) to run (the remaining wire that isn't brown) A lower reading would be expected
2. Measure common to start (brown without a stripe) a much higher reading...
3. Measure start to run. The sum..


YouTube - how to bench check a central A/C blower motor


Measuring the cap isn't too hard either.

[gramsay]

Originally Posted by Houston204

Ohm out your motor.

1. Measure common (black) to run (the remaining wire that isn't brown) A lower reading would be expected
2. Measure common to start (brown without a stripe) a much higher reading...
3. Measure start to run. The sum..


YouTube - how to bench check a central A/C blower motor


Measuring the cap isn't too hard either.

Hello Houston204,

I ohmed out the fan motor with nothing else connected.

1. Measure common (black) to run (the remaining wire that isn't brown) A lower reading would be expected

1. Measured black to orange.
Reading was 19-ohm.

2. Measure common to start (brown without a stripe) a much higher reading...

2. Measured black to brown.
Reading was 71-ohm.

3. Measure start to run. The sum..

3. Measured start(brown), run(orange).
Reading was 90-ohm.


I measured the capacitance on both run and start capacitors and both were zero (0).

I noticed something with the run capacitor
(50.0/3.0 MFD - 370 VAC 50-60Hz)
which has 3 terminals.

Green - Fan - Lower Value
Black - C
White - Herm - Higher Value

The actual connections were:

Green - no connections
Black - Three orange wires (Fan, Terminal Block, Start Capacitor)
White - Purple wire to compressor


It seems the Fan-orange wire is not connected to the Run cap. Green terminal.
Not sure if that is a problem.

Peace,
GR

[Houston204]

You probably have a second cap. What do the 2 brown wires connect to.






If your start cap and compressor run cap read zero, the compressor would't run. What meter are you testing with?
I might be able to look up your manual.




YouTube - how to check a capacitor

[gramsay]

Originally Posted by Houston204

You probably have a second cap. What do the 2 brown wires connect to.






If your start cap and compressor run cap read zero, the compressor would't run. What meter are you testing with?
I might be able to look up your manual.




YouTube - how to check a capacitor

Hello,

Thanks for your help.

The brown wire from the Fan Motor goes to Start Capacitor

The brown wire from the contactor block goes to the inside of house/AC.

Multimeter is:

Cen-Tech (7-Function Multi-Tester)
Item # - 90899

Peace,
GR

[Houston204]

The brown wire from your motor should connect to the Fan terminal on your dual capacitor, not the start cap.

That meter will not measure microfarad.

If you have replaced the motor before, you might read the cap mfd size on the motor nomenclature.

[gramsay]

Originally Posted by gramsay

Hello Houston204,

I ohmed out the fan motor with nothing else connected.

1. Measure common (black) to run (the remaining wire that isn't brown) A lower reading would be expected

1. Measured black to orange.
Reading was 19-ohm.

2. Measure common to start (brown without a stripe) a much higher reading...

2. Measured black to brown.
Reading was 71-ohm.

3. Measure start to run. The sum..

3. Measured start(brown), run(orange).
Reading was 90-ohm.


I measured the capacitance on both run and start capacitors and both were zero (0).

I noticed something with the run capacitor
(50.0/3.0 MFD - 370 VAC 50-60Hz)
which has 3 terminals.

Green - Fan - Lower Value
Black - C
White - Herm - Higher Value

The actual connections were:

Green - no connections
Black - Three orange wires (Fan, Terminal Block, Start Capacitor)
White - Purple wire to compressor


It seems the Fan-orange wire is not connected to the Run cap. Green terminal.
Not sure if that is a problem.

Peace,
GR

Hello,

The Fan Motor was ohmed-out as you suggested and the values seek ok.

19, 71, 90ohm.

Does that mean the fan motor is good ?

Peace,
GR

[gramsay]

Originally Posted by Houston204

The brown wire from your motor should connect to the Fan terminal on your dual capacitor, not the start cap.

That meter will not measure microfarad.

If you have replaced the motor before, you might read the cap mfd size on the motor nomenclature.

Hello Houston204,

The colored-wires I mentioned were as is when the AC was working properly.

It is strange that there is no connection to the Green/Fan/Lower Value of the Dual-Run-Cap.

Thanks for the tip on the meter. It does 'not' measure capacitance.

I have not replaced this fan motor. This is the first AC problem, I've had.

The info on the fan-motor is:

Emerson
Model: KA55HXEMH-883
5 MFD
370VAC
1/3 HP
208-230V
60hz
2Amp
PH-1
1075 RPM


Peace,
GR

[Houston204]

Sounds like you need a 50 / 5 mfd 370VAC dual capacitor to me.

Are you certain that your motor specs 5 mfd and your cap is only a 3 microfarad?

If your motor has 3 leads (no brown with stripe) it should wire to a dual cap as shown in my "Dual Cap" diagram. Brown connects to Fan, sub your orange for the diagram violet.

I hope you didn't have the fan motor "start" connected to a 88-108 mfd or larger start cap, when it calls for 5 mfd run cap.

[gramsay]

Originally Posted by Houston204

Sounds like you need a 50 / 5 mfd 370VAC dual capacitor to me.

Are you certain that your motor specs 5 mfd and your cap is only a 3 microfarad?

If your motor has 3 leads (no brown with stripe) it should wire to a dual cap as shown in my "Dual Cap" diagram. Brown connects to Fan, sub your orange for the diagram violet.

I hope you didn't have the fan motor "start" connected to a 88-108 mfd or larger start cap, when it calls for 5 mfd run cap.

Hello Houston204,

Yes, the motor spec is 5-mfd, while the run-cap is 50.0/3.0-mfd.

I made a diagram of the existing connections and wire-colors before I disconnected anything.

At that time as mentioned the fan-motor-brown wire went to the start-cap. And the run-cap-green-fan had no connections.

Not sure how the AC could have worked as is.
But, I have had some weird-bizarre vandalism at my house over the recent months. This could have been another vandalism attempt.

I checked the wiring diagram inside the condenser unit and confirmed that the fan-motor-brown wire should go to the
run-cap-fan-green.

The fan-motor(start)-brown was going to the start-cap of 5-mfd.

Is the fan-motor itself, ok since the ohm measurements summed-up ?

I am trying to get a DMM with capacitance reading this weekend to finally confirm the run/start caps.

I was thrown off by my DMM which doesnt measure capacitance.

Thanks,

Peace,
GR

[gramsay]

Hello,

Today I was able to go to an AC Supply Store.

They measured both caps. The run-cap of 50/3mfd has a defective green-fan terminal. The other cap that I said was a start-cap of 5mfd is good. However the sales guy kept on calling it a run-cap also.

He said a fan-motor must have been replaced before which required a run-cap of 50/3mfd. The existing fan-motor requires a 50/5mfd. Somehow the green-fan terminal went bad and they wired in the 2nd ... start/run-cap of 5mfd to match the newer existing fan-motor.

The sales guy says its either the fan-motor or the voltage going to the fan-motor.

Peace,
GR

[Houston204]

Was this wired as shown in the universal replacement motor diagram?

[Houston204]

It could also be a wiring issue.

With an orange wire to the condenser fan motor, it sounds like an OEM motor. Did it have 2 brown wires?

If not, did it have a jumper wire from C on the dual cap or the side of your contactor that orange connected to (run), to the second side of your fan motor run capacitor?

[gramsay]

Originally Posted by Houston204

Was this wired as shown in the universal replacement motor diagram?

Hello Houston204,

Yes, the existing wiring was like the universal replacement motor diagram.

I have two(2) caps as mentioned.

I thought the larger/round dual-cap-3-terminal, 50/3mfd was called the run-cap.

Then the smaller/oval 2-terminal, 5mfd was called the start cap.

Thats what the wiring diagram of my unit says.

But, then the sales guy called the small-cap a "run"-cap and also that universal replacement motor diagram.

Peace,
GR

[gramsay]

Originally Posted by Houston204

It could also be a wiring issue.

With an orange wire to the condenser fan motor, it sounds like an OEM motor. Did it have 2 brown wires?

If not, did it have a jumper wire from C on the dual cap or the side of your contactor that orange connected to (run), to the second side of your fan motor run capacitor?

Hello Houston204,

If it was a wiring issue, then I dont think the AC would have worked so long from the time I moved into the house-2005 until now.

Can you give some insight into the voltages at the contactor block, when the compressor and fan motor are disconnectd.

With the thermostat on.....
I measured 120VAC into the contactor block and also on the other side of the contactor block. The solenoid/transformer closed ok, to get voltage on the other side.

However the brown-side of the contactor block was unstable at 24-25vAC and the yellow-side was zero (0).

The fan-motor has brown, black, orange wires.

Q>If not, did it have a jumper wire from C on the dual cap or the side of your contactor that orange connected to (run), to the second side of your fan motor run capacitor?
A>Yes.

Peace,
GR

[Houston204]

If you get 240VAC between black and orange when the contactor pulls in and your cap is good and wired correctly as you have stated, you need a motor.


I have never performed that old timers cap test. I have seen it performed by the senior techs when I was a young man though.
I've always measured capacitance.

[gramsay]

Originally Posted by Houston204

If you get 240VAC between black and orange when the contactor pulls in and your cap is good and wired correctly as you have stated, you need a motor.


I have never performed that old timers cap test. I have seen it performed by the senior techs when I was a young man though.
I've always measured capacitance.

Hello,

I've decided to buy a replacement fan motor and a dual-run-cap.

I have a new issue of trying to remove the fan blade.
I removed two (2) set-screws.

I used WD-40 to try and loosen the blade to the motor shaft.
I'm able to hold the motor shaft nearest to the motor in place with pliers. I can move/rotate the blade horizontally but I cant
get the blade up/off vertically.

Any advice ?

Peace,
GR

[Houston204]

Sand the motor shaft, file any possible damaged areas (pliers?), lubricate the shaft with some WD40, hold the shaft with an adjustable crescent wrench and spin the blade off.

It may be necessary to spin the blade in to sand closer to it before spinning it out.

They make a puller for this but I rarely require it.

[gramsay]

Originally Posted by Houston204

Sand the motor shaft, file any possible damaged areas (pliers?), lubricate the shaft with some WD40, hold the shaft with an adjustable crescent wrench and spin the blade off.

It may be necessary to spin the blade in to sand closer to it before spinning it out.

They make a puller for this but I rarely require it.

I'm making some progress now.
The key is the WD40.
I'm able to lubricate the shaft. Hold the shaft with pliers and turn the blade.
I have about 2" left to go.

Thanks.

Peace,
GR

[gramsay]

Hello,

Problem resolved.

I could not get the blade off the bad fan-motor.

After searching and looking for a replacement fan-motor.

I decided to have an A/C fix my motor.

A new A.O. Smith fan-motor was installed (5-wires, vs. 3-wires old fan-motor), new 7.5mfd capacitor. Maintenance/Service of entire AC System.

Even the A/C Professional had a hard time getting the blade off.

Total cost was $250.

Other quotes were as high as $400-$500.

A/C is back on, but fortunately the weather has been cool, since the A/C broke.

Today was 77.

Peace,
GR