My house AC won't work.
Split unit with evap inside and condenser outside.
Compressor sounds like it is struggling and the condenser fan won't spin up.

Went to get a new Start/Run Capacitor but the old one had no legible numbers on it. Guys at the HVAC place and I worked as best as we could and found what we thought was the one.

Compressor still struggles and the condenser fan slowly starts up runs a little but shuts off again.

I know it is time for a new unit but would like to get another few weeks out of it while I shop around for the new one.

The side panel has a log that says Miller and the UL/Info tag says Nordyne at the bottom with the model Number ACZD-024BA-1 at the top.

I can not find anything about the correct Capacitor. Is there a way to size the capacitor or know of a supplier with ooooold books?

Ideas?

Thanks

I don't know if this will help or not. https://www.building-center.org/nordyne-hvac-age/

I would check the voltages at both fan motor and compressor,
before start,
during start up
and when motors seem near run speed rpm.

Since you have two separate motors it is a clue that BOTH show a slow start up that is a sign of low voltage at high amp start load.

Look for high resistance connections with “green death crud” and check fuses.

The Chinese made start capacitors do fail very frequently with short lives.
The “two capacitors in one case” seem to fail even more frequently.

The factory original USA made, with the now illegal PCB oil filled capacitor, on my Amana AC unit lasted from 1983 to 2011
but the Chinese capacitors seem to last 2-4 years, and the parts store clerks confirm this.
The made in Mexico capacitor now has lasted 5 years.

Definitely search on line for a copy of the manual for your unit with a wiring diagram, amp draws, freon pressures, etc.

There are a lot of scam manual sites online now, so use caution.

I found my Amana manual online at

https://www.manualslib.com

i was told if they look 'bloated' , they should be replaced

i have '4' outside units (3x4t and 1x 2.5t) and last year the a/c co. i use said '3' should be replaced at..... 625bucks.... since the cap's cost around 25bucks, thats highway robbery- i checked em all , and they look ok... not bloated... i mite change em this year.... myself... as its a pretty easy swap...

Sure seem to be having a rash of problems with single phase capacitor start/capacitor run motors lately. Ok, first thing, is the compressor motor a separate motor or is the compressor one of the sealed can varieties? What is the nameplate information on the compressor/compressor motor itself? Condenser fan, what is the nameplate information on it? Sometimes there is a wiring diagram on the inside of one of the covers, is there one?

Without some info, all I can give you is guesses.

Youd think there should be a table or formula to figure it out if you know the amps of the fan motor and compressor.
I had to replace the capacitor in one of ours last year and the biggest problem was trying to find one locally. Either no one had them or they only wanted to deal with a company not an individual and the only place I could find was across town and wanted several times what they are worth. Ended up buying it online.

I can guaranty if it’s good, touch the connectors it’ll knock the heck out of you, ask me how I know. Ground them first, a ohm tester will show if it’s good,

A ohm test won't tell you it's good. Only that it is completely bad.

Capacitors need to be read by a capacitor tester to see if they are good. Their values can change rendering it useless for the application, but it will still "pass" an ohms test and still zap you.

Like any job, you need the right tools. First, search online using the model number of your unit for the specifications of the capacitor. You may be able to locate a schematic of the unit online that will give you the specification of the capacitor. Next, see if the capacitor is out of specification. You may need to buy a Fluke 101 or similar meter if you don't have one so you can read the capacitance. The units will be microfarads. Replace if out of specification. Go where the Pros go to buy it so you don't get hosed.

Thanks to everyone who has replied.

Here is the wiring diagram inside the cover, the compressor labels, the Capacitor I just installed (the original one was unreadable), the fan motor label (Fan spins fine and was replaced a few years ago).

I tested both fuses to it and they had continuity.

Unit Label

I know it is oooold but I just want a few weeks to pick out a new system I want not it was the only one I could find right away.

Thanks

The condenser motor wiring diagram calls for 5MFD @ 370v. That cap you have is a 5MFD @ 440v piece. I've seen caps that are compatible with both voltages, but they're usually labeled as such.

Never seen a bad capacitor make a fan not spin.
Compressor won't even try and start if the capacitor is bad.

Cool. I didn't see that.

Any idea if the 35 is correct for the other side of the capacitor?

We were able to make out something +5 370v on the old capacitor but the "something" is the part i can't figure out.

I could NOT find [censored] based on the model number of AC unit itself. That thing flat out doesn't exist as far as Google is concerned. If I'm reading the serial correct though, it was made in 1989 by Nordyne, now known as Nortek.

Instead, I cross referenced the model numbers of the compressor and fan motors to find the required capacitor ratings.


For the compressor: https://www.dcne.com/UserFiles/Reso...nElectric-Copeland_00324_2_9_38_BROC.pdf

New replacement model for the CRD4-0200-PFV is a CR24K6-PFV. It says 35MFD at 370v.

For the fan motor I used the wiring diagram you posted and a couple other sources online to verify.

So a 35+5MFD 370vAC is what you need.

I misspoke in my last reply. You can use a higher rated voltage cap. What you have now has the correct capacitance ratings for both motors, so it should work. Maybe it's bad out of the box.

Good sleuthing. I followed the same path and came up with the same conclusion. The fact that the fan works but the compressor doesn't seems to bear out MarkZ's comment that your new capacitor may be defective.

Thank you all for the help.

I am beginning to wonder if the problem is something else because the fan turns, but starts slow. It never seems to reach full speed then after a while stops. After a little while starts the cycle again. The compressor just makes a constant struggling sound like it's working but not as correctly. I assumed since they are both on the same Capacitor it was the Capacitor. Now I wonder if they are suffering from low current/voltage or the compressor is failing and drawing so much current the fan is starved for power.

I'm going to check the voltage at points through the circuits, replace the fuses (just in case, even thought thy have continuity) and bypass the relay that turns the system on. Any other ideas? I do not have an A/C Ammeter but I will buy one if I need to.

Thanks again.

The compressor could be mechanically dragging, quite common on older hermetic compressors. I would put a hard start capacitor on the compressor, and use the 5 UF 370v side of the capacitor you have for the condenser fan motor. Check all of your electrical connections for loose and or corroded terminals.

MarkZ (or anyone else with A/C knowledge), could a plugged up condensation line make it act like that?

I had to clean mine yesterday.

It could also be a stuck Thermal Expansion Valve (TXV) that is preventing refrigerant flow and jamming the compressor.

The 35/5 should have done the trick if it was bad
Sometimes on real old compressors i put a booster on .
Fan runs or doesnt ??

Uh, oh. I assumed from your posts the fan was operating normally and the compressor wasn't. If the fan is still having problems this puts an entirely different light on the problem. I'd concentrate on the fan first. It's really simple, it's a permanent split capacitor motor.

Single Phase Motor Starting

The fan could not start without the capacitor, there would be only one winding energized. The fact that it will start but then stops, and then restarts sounds like either a capacitor problem or a connection problem. If you can get the fan to work, whatever you find will probably apply to the compressor also. I'd recommend disconnecting the compressor and working with the fan alone until you find out what's going on. Don't what to shell out the compressor with your troubleshooting efforts..

Okay Update time....

Initially the fan wouldn't spin and the compressor struggled.

I dug into it today and the Capacitor seems to have resolved/helped the Compressor problem. Coils are getting hot but airflow is low through the condenser.

The fan spins ok by hand. With the new capacitor the fan now starts slow but never gets full speed. Eventually it slows to a stop and the cycle begins again. When it stops the fan is hot hot hot. Compressor is cool (not hot or cold just cool).

I am beginning to think the Cap and the fan died at the same time. So you are correct to fix one problem and then the other. I am going to get a new fan this week and see if we are good to go. If not I will look harder at the compressor but hopefully it will be ok.

I am still going to get a whole new unit but I would rather shop ahead of the failure instead of in an emergency situation.

Thank you all for the help and advice.

I still wouldn't rule out a bad cap. Especially if the fan isn't coming up to speed.

If the fan is working at all, the motor is probably fine. The fact that it's cycling still points to a capacitor problem or a poor connection problem.

With the additional information
it points toward your 1/4 HP at 1075 RPM FASCO fan motor having developed a short in its winding
and opening its internal thermal protection switch as the electrical arc inside heats things up.

You might be able to smell the internal arc burning.

Pulling an old fan hub off an old motor shaft can inspire you to invent new curse words,
especially if you do not have the right puller and rust penetrant spray.

Sometimes it is better to just buy new hub and fan.

Lau parts makes a new super quiet fan design that also uses less power.
This fan series is called the Cobra Blade.
It looks like wild Klingon double bladed killing weapon.

Starting on page 23 here:

https://www.lauparts.com/-/media/la...2017BlowersPulleysWheels_REV08062020.pdf

A plain multimeter without a capacitance measuring position
can still be used with a clock that can measure seconds
to roughly find a capacitance value.
Google or youtube search for that.
You now have two “double” capacitor cases which have 4 capacitors that can be tested and compared with this method.

There is an old moparts post on doing this capacitance test with Harbor Freight “free” digital multimeters.

I had to replace ours for the first time last summer. The original did not say anywhere where it was made, nor does the replacement. The replacement is a TOTALINE brand which is the replacement components division for Carrier. It's a 40+5 MFD. Worked perfectly on our 16 year-old Goodman.

Thats how ours went out. I thought it was strange too.

Thank you all for the responses.

Today I finally had time to replace the Condenser fan and all is well.

Apparently the Capacitor and Fan went bad at the same time. After replacing the Capacitor, compressor & fan worked better but the fan was still bad.

All your help was much appreciated, without it I would still be in a pickle.

System is still crappy and old but your help bought me a month or two to pick the replacement system I want and not whatever I could get.

Depending on its age you might be better off fixing the old one. The new ones are cheaply made with thin copper tubes.

I am glad you found and fixed the problem.

Keep in mind with new HVAC systems:

1 The inside tubes of new evaporators and condensors have “cut spiral groves” that slightly save electricity but can greatly shorten the time before leaks come. Bad trade off.

2 Freon 410 is less efficient and as a mix of 2 gases more complex than older Freon 22 which is only available reclaimed and more expensive

3 New systems have more complex and costly parts and inherently harder to be reliable

4 New systems can be much quieter and dehumidify better

5 I am leaning toward two, three, four Minisplits rather than one central AC unit because
I do not want 100% of the cooling system down,
and I want to be able to use a smaller, quieter generator to run at least one cooling unit during sleep when the power is off.

I agree the long term dependability of the old stuff is probably better but this unit is undersized for the house and always was.
Besides having an undersized AC unit, I have had to clean the gas burner heat exchanger several times of rust which means that heat exchanger is 30+ years old and on borrowed time.

On a plus side to this system, in 30 years I have had to replace the condenser motor and capacitor twice. I also had to rebuild the drain tray under the evaporator, replace the condensate pump twice, several thermocouples, and the house fan motor once. No single part was more than $90 and was easy to replace. I do not think a new system will be so kind and that is why I hate to see it go, but it is time. Nobody has parts books that include it anymore, so finding parts is problematic when the labels disintegrated years ago.

Even though installing a new one is easy enough, I may pay someone to install it for the extended warranty.

Thank you all again.