Hi All,
I very much apologize if this question is inappropriate for the All About Circuits. The reason I am asking here instead of a HVAC forum is to get an answer from people knowledgeable in PSC motors.

The run capacitor for the PSC condensing fan on my house's air conditioner reads Open on the capacitance meter, thus the fan is inoperable. The run capacitor's label shows it as 8 microfarad / 450 volts. Searching for a run capacitor with 8 microfarad revealed only one from one source and it costs $54.00.

The motor is 208/240 volt, single phase, 1/3 HP
It was made by Zhongshan Broad Ocean motor Company LTD & is part number YDK-200S64026-01. I can;t find capacitor data for it.

The question is:
Can I substitute a more common 7.5 or a 10 microfarad without damaging the motor?
Which direction is safer- 7.5 or 10?
And, can I substitute a 370 volt instead if 450? (If memory is correct, that is OK)


A Second Question:
If you don't mind a second question, I'd like to pose it here.
For over a year, the indoor fan motor when on the highest speed will periodically hesitate. The hesitations are a slight, but noticeable audibly, slow down. They are brief at perhaps a second in duration. That capacitor is rated 15 microfarad. It reads the same on the meter. The voltage reading stays constant coming into the air handler.
Could this be a capacitor problem? Or, is there a more likely cause?


Thank You All for helping me select an appropriate run capacitor for the outdoor motor and for any ideas of what to look forward solving the indoor fan hesitation.

Paul

 

Yes you can use 10uf it should work OK.
Where are you located, (OK I see Detroit) Btw, I Have a whole shelf of these N.A. made 10uf start caps doing nothing now im retired. (Canada)
Whatever you use, ensure it is a motor run rated!
Re: Second questipn .
Are you sure it is not a friction problem.?

 

Yes you can use 10uf it should work OK.
Where are you located, (OK I see Detroit) Btw, I Have a whole shelf of these N.A. made 10uf start caps doing nothing now im retired. (Canada)
Whatever you use, ensure it is a motor run rated!
Re: Second questipn .
Are you sure it is not a friction problem.?

Thank You MaxHeadRoom for taking time to reply and to explain. I very much appreciate your advice.

To replace the 8 mfd, I'll do as you suggested and use a ten. It's 25% over, but as I understand from memory being over with a run capacitor in a PSC motor is better than being under (the 7.5).

Regarding the hesitation on the indoor motor, the fan spins freely when off. I neither hear nor feel rubbing or tight spots. With a volt meter on, the hesitation is too short for the min/max or display to catch it. I was hoping to find that there was a voltage drop problem. The run capacitor for this PSC motor tests good.

One interesting thing is that this air handler is a mini-duct unit by Hi-Velocity in Edmonton. Unlike a standard air handler, pressure builds up in the unit in order to push the air eventually through 2" ducts. The indoor fan motor works hard!

Thinking along the lines of restricted air flow, I briefly opened a section of duct to remove back pressure while on high speed and the hesitation stopped. I also noted that it only happens when the fan is on its fastest speed- cooling or humidifying in winter. On the slow speed that it is on 24 hours a day, the fan runs smoothly. And, the hesitation is not rhythmic. It may appear once in a minute or several times in a minute.

Since the motor is 19 years old and moves 24 hours per day, perhaps the motor is the problem.
But, note that the above is a guess since I can't find a verified problem.

Thank You Again for helping and for an idea about the motor surging problem. Hopefully I will find the cause.
Thank You also for suggesting the appropriate capacitor for the outdoor fan motor.

Paul

 

"In Edmonton" Canada??

 

8uF 450VAC

But it does not say motor run. @MaxHeadRoom, What characteristics make it (un)suitable as a motor run capacitor?

 

I purchased a 10MFD motor capacitor at my nearby hardware store. FRENTZ, if the TS is in my area.
The characteristics of a capacitor to make it suitable for motor use are an AC rating, and the ability to handle the power (heating) from AC operation. That usually is associated with physical size. apolarized cap is not suitable for ANY AC motor application!!

 

The OP requested a PSC so obviously should not be electrolytic.
The motor run style are best purchased from a N.A. manuf. NOT China!
The ones I use are quality oil filled paper type, Never lost one yet!

 

8uF 450VAC

But it does not say motor run. @MaxHeadRoom, What characteristics make it (un)suitable as a motor run capacitor?

Quote "The run capacitor for the PSC (Permanent Start Cap) motor "
A start capacitor is usually larger uF, bi-polar electrolytic and cannot support more than a few seconds in circuit!

 

Quote "The run capacitor for the PSC motor "
A start capacitor is usually larger uF, bi-polar electrolytic and cannot support more than a few seconds in circuit!

The capacitor I linked to is an AC rated 460V film capacitor (non-polarized). I am asking what else to look at to determine if it is suitable as a run capacitor. I really don’t know, not trying to argue with anyone.

 

Generally they are listed as motor run capacitors, except the very small (low current) motors which tend to use other plate insulation mediums.

 

"In Edmonton" Canada??

Yes. They are a second generation family owned company. Very fine products, if I may be judgmental.
Edmonton, Alberta is where the company, Energy Saving Products, is located. https://hi-velocity.com/
My air handler & refrigerant coil were built in Canada. I don't know if they still build "on shore" or had to outsource.

 

8uF 450VAC

But it does not say motor run. @MaxHeadRoom, What characteristics make it (un)suitable as a motor run capacitor?

Thanks for the link to the capacitor, BobTPH!

 

my nearby hardware store. FRENTZ, if the TS is in my area.

Without question, the world's best hardware store!
I've worked all over the country, requiring an awful lot of hardware store trips. Many small town stores are great, but none beat Frentz. (Washington Hardware on Van Dyke & 28 Mile was great in the 70's, but alas is gone. Nuts, bolts and back room moonshine to go. Truly a full service store!)

Every time in the last probably 50 years I've walked into Frentz I've been greeted by an employee who is eager to help. Well worth going out of the way. My wife grew up in the area and her dad once said he'd been going there since the 40's.

I didn't think of trying Frentz for the 8 mfd capacitor. Chances are they have one in the seemingly magical back room- where at least one if everything ever made resides. Once I made an off-hand comment about heading to the plumbing supplier to pick up a radiator spud wrench for a 6" diameter nipple. "Just a minute, I think we have one." came the reply. Sure enough! B190 V-belt? Yup.

 

Until this capacitor search, I've never seen what is called a "Dry Run Capacitor". Are those intended for PSC motor use? I'm just curious.

For the motor in question, I plan to use oil filled, paper, North American Made in 10 mfd, as mentioned above by MaxHeadRoom.

Here's a link to one of the dry type:
https://www.supplyhouse.com/Packard-PDCF8-440V-Dry-AC-Motor-Run-Capacitor-8-MFD

 

The one in the link seems good, also right value!

 

The one in the link seems good, also right value!

Thanks MaxHeadRoom.
I ordered one this morning. For $3.80 it's certainly worth trying. Unfortunately, not North American made. (American company)

 

Let us know how it works out

 

Really, at "Frentz", when I asked for a motor capacitor at the service counter, the person just reached under the counter for it. Like possibly they sell a few of them.

The other thing that defines motor application capacitors is their size. Bulk is also available to reduce the heat density. The two inch diameter by six inch long run capacitor can handle a lot more power than the one by 3 capacitor, even if they are the same capacitance rating.

 

Really, at "Frentz", when I asked for a motor capacitor at the service counter, the person just reached under the counter for it. Like possibly they sell a few of them.

With the temperatures the last few weeks, I'll bet that they sold a boat load of of start & run capacitors. Maybe a condensing fan motor or two as well.
Paul
PS: Next time you're in Frentz, go to the nuts, bolts and washers aisles and look at the floor. Makes me smile every time.

 

Really, at "Frentz", when I asked for a motor capacitor at the service counter, the person just reached under the counter for it. Like possibly they sell a few of them.

Sad news to share, Mr Bill:
Frentz is closing. The last of the real hardware stores!
Wow, after the family owning it for 93 years and it having been in business (hardware & cleaners) before even that. That's a great run!

John told me that there isn't a locked in time line. They are willing to wait for a good price for the building. I think the DIA should buy and frame the floor in the nuts & bolts aisle. It's a masterpiece.

The brothers & their wives deserve some happy retirement time!
Were I younger, I'd be happy to buy it and keep every, single one of the employees that they have.
Paul