Motor question

"oh shit" mode. However I found that the run capacitor was bad and it is up and running fine for about twenty bucks from the local W.W. Grainger. A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R22 system which compicates matters even further. I would have had to convert to R134 or wait months for a compatible condensing unit.

last year it seems. Now I know capacitors don't all go all at once and I wonder now if decreased capacitance or high ESR might have been adversely affecting the unit's efficiency.

capacitor, it is a run capacitor. Would it be worth it, in these days of ever increasing energy costs to go out and actually check these capacitors and change them when they get marginal ?

Yes, it would cause the motor the exert more current than should be, if the run cap were reduced in value. Also, makes it harder to start and the compressor would operate slower..

Jamie

I have not measured it this year, but I have been drawing 6 amps on my compressor. If something changes the current should change. Good to monitor.

Greg

n the "oh shit" mode. However I found that the run capacitor was bad and it= is up and running fine for about twenty bucks from the local W.W. Grainger= . A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R22 s= ystem which compicates matters even further. I would have had to convert to= R134 or wait months for a compatible condensing unit.

gh as last year it seems. Now I know capacitors don't all go all at once an= d I wonder now if decreased capacitance or high ESR might have been adverse= ly affecting the unit's efficiency.

o 1,750 or 3,450 RPM or whatever, so if less efficient then it would stand = to reason that they would be pulling more current than they should.

capacitor, it is a run capacitor. Would it be worth it, in these days of e= ver increasing energy costs to go out and actually check these capacitors a= nd change them when they get marginal ?

I also have 3 zones of R22 A/C's. What brand is yours? Someone 'diddled' with the valve on zone 3 and f$500 worth of R22 [9.5 lb.] went into the atmosphere. To replace unit to 'more efficient and environmentally friendly' is at least $1700 arrrgggg!

Without freon the unit would not run. Repair people [from their office] said probably capacitor, because it's the first thing to go out. Hmmm.

When the guy came out he checked pressure on the working units, and verified lack of freon prevented zone 3 form operating, but I never saw him check the capacitors! Since a bad capacitor can impact efficiency and is always the first thing to go, I'm surprised it's not one of the first items to check. Any thoughts?

in the "oh shit" mode. However I found that the run capacitor was bad and = it is up and running fine for about twenty bucks from the local W.W. Graing= er. A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R22= system which compicates matters even further. I would have had to convert = to R134 or wait months for a compatible condensing unit.

high as last year it seems. Now I know capacitors don't all go all at once = and I wonder now if decreased capacitance or high ESR might have been adver= sely affecting the unit's efficiency.

do 1,750 or 3,450 RPM or whatever, so if less efficient then it would stan= d to reason that they would be pulling more current than they should.

rt capacitor, it is a run capacitor. Would it be worth it, in these days of= ever increasing energy costs to go out and actually check these capacitors= and change them when they get marginal ?

If the system has a relay that opens the circuit to the compressor when the pressure is low, the tech might have made the correct first move.

as in the "oh shit" mode. However I found that the run capacitor was bad an= d it is up and running fine for about twenty bucks from the local W.W. Grai= nger. A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R=

s high as last year it seems. Now I know capacitors don't all go all at onc= e and I wonder now if decreased capacitance or high ESR might have been adv= ersely affecting the unit's efficiency.

to do 1,750 or 3,450 RPM or whatever, so if less efficient then it would st= and to reason that they would be pulling more current than they should.

tart capacitor, it is a run capacitor. Would it be worth it, in these days = of ever increasing energy costs to go out and actually check these capacito= rs and change them when they get marginal ?

I was referring to the GOOD units. Why weren't the caps checked in any manner on those units.

in the "oh shit" mode. However I found that the run capacitor was bad and it is up and running fine for about twenty bucks from the local W.W. Grainger. A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R22 system which compicates matters even further. I would have had to convert to R134 or wait months for a compatible condensing unit.

high as last year it seems. Now I know capacitors don't all go all at once and I wonder now if decreased capacitance or high ESR might have been adversely affecting the unit's efficiency.

do 1,750 or 3,450 RPM or whatever, so if less efficient then it would stand to reason that they would be pulling more current than they should.

capacitor, it is a run capacitor. Would it be worth it, in these days of ever increasing energy costs to go out and actually check these capacitors and change them when they get marginal ?

Time. The tech woul have had to kill the power to the other two units, open them up, and check the cap. Under ideal circumstances that would add another half hour of labor to the bill. Of course, you appreciate the benefits of preventative care and would not have questioned the extra $50 on the bill. Other, less intelligent people would simply accuse the tech of padding the bill.

PlainBill

I was in the "oh shit" mode. However I found that the run capacitor was bad= and it is up and running fine for about twenty bucks from the local W.W. G= rainger. A simple dual AC 440 volt capacitor, not a compressor. Plus it's a= n R22 system which compicates matters even further. I would have had to con= vert to R134 or wait months for a compatible condensing unit.

t as high as last year it seems. Now I know capacitors don't all go all at = once and I wonder now if decreased capacitance or high ESR might have been = adversely affecting the unit's efficiency.

ng to do 1,750 or 3,450 RPM or whatever, so if less efficient then it would= stand to reason that they would be pulling more current than they should.

a start capacitor, it is a run capacitor. Would it be worth it, in these da= ys of ever increasing energy costs to go out and actually check these capac= itors and change them when they get marginal ?

ot

I never mind an added cost if it is 'additional', announced as additional, and undertaken at my request.

However, I contracted with this firm to come out and CHECK my units at a fixed price. Words mean something. "Check my units at $49.95 cost." is exactly that. And, if this component does fail as often as claimed and if this component does eat power as it fails; then it is reasonable for me to assume that this component is and should be part of the check when a tech comes out. After all, there's not much difference between checking the cap and measuring the pressure except one is electrical and the other mechanical. Retrospectively, surprised power during operation was not measured and noted at least for future reference.

Don't get me wrong, I got my money's worth with the single pressure measurement that I can't make and enjoyed the education. Impressive to me was after the tech measured the pressure he told me the temp inside my house! May be obvious to those in the business, but pure magic to me.

was in the "oh shit" mode. However I found that the run capacitor was bad and it is up and running fine for about twenty bucks from the local W.W. Grainger. A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R22 system which compicates matters even further. I would have had to convert to R134 or wait months for a compatible condensing unit.

high as last year it seems. Now I know capacitors don't all go all at once and I wonder now if decreased capacitance or high ESR might have been adversely affecting the unit's efficiency.

to do 1,750 or 3,450 RPM or whatever, so if less efficient then it would stand to reason that they would be pulling more current than they should.

start capacitor, it is a run capacitor. Would it be worth it, in these days of ever increasing energy costs to go out and actually check these capacitors and change them when they get marginal ?

I beg to differ. The only 'cost' that was fixed was the amount you were charged. Perhaps you have heard - 'Time is Money'. You MIGHT have meant "Check all the units and bring them up to peak performance for $49.95". What they certainly heard was either "Fix the non-working unit for $49.95", or more likely "Find out what is wrong with the non-working unit of $49.95 and tell me how much it will cost to repair it".

Now, if you were taking advantage of a 'Spring AC checkup for $49.95', I would agree you had a valid point.

PlainBill

No, in general, I don't think the run caps are any more failure-prone than any other part. I have had exactly ONE run cap blow in 40 years. I have had a number of other things fail over that time. Also, if the cap is not blown open like a grenade, exactly HOW do you check it? Probably any time up to a minute before exploding, no test that won't harm it will detect a unit nearing failure.

Jon

nd I was in the "oh shit" mode. However I found that the run capacitor was = bad and it is up and running fine for about twenty bucks from the local W.W= . Grainger. A simple dual AC 440 volt capacitor, not a compressor. Plus it'= s an R22 system which compicates matters even further. I would have had to = convert to R134 or wait months for a compatible condensing unit.

not as high as last year it seems. Now I know capacitors don't all go all = at once and I wonder now if decreased capacitance or high ESR might have be= en adversely affecting the unit's efficiency.

going to do 1,750 or 3,450 RPM or whatever, so if less efficient then it wo= uld stand to reason that they would be pulling more current than they shoul= d.

ot a start capacitor, it is a run capacitor. Would it be worth it, in these= days of ever increasing energy costs to go out and actually check these ca= pacitors and change them when they get marginal ?

one

.]

nd

go

nd

er

s not

ou

Wow! and, English is my primary language! Your last paragraph was closest.

I found the zone 3 not working, called the company. THEY offered the fixed price to review ALL the units *and* "...while he's there doing the two working units, the tech can see if he can find out what's wrong, that way you won't be charged for just coming out to look at a non-functional unit." so it was my understanding, and I blelieve their understanding, that the tech was coming out to check 2 functioning zones and while he's here take a look at the non- functioning unit to see if he can see what's wrong and quote on repair.

But, after reading about the cap, seems like the 'health' of the cap is more important than the exact pressure values.

Test the ESR, like any electrolytic.

cap

Interesting, the service/repair company claimed cap was one of the major reasons for a unit to fail to run at all.

In electronic applications it is often possible to measure the cap in situ, and determine its 'health' to a degree. My understanding is that the standard failure mechanism is the esr starts increasing, the cap dissipates more power, getting hotter the esr continues to increase, and eventually POP. Starts as low as 10-30 milliohms then can climb up passed 1-2 ohms depending. There are a whole bunch of DIY projects to make inexpensive esr cap measurment instrumentation.

was in the "oh shit" mode. However I found that the run capacitor was bad and it is up and running fine for about twenty bucks from the local W.W. Grainger. A simple dual AC 440 volt capacitor, not a compressor. Plus it's an R22 system which compicates matters even further. I would have had to convert to R134 or wait months for a compatible condensing unit.

as high as last year it seems. Now I know capacitors don't all go all at once and I wonder now if decreased capacitance or high ESR might have been adversely affecting the unit's efficiency.

going to do 1,750 or 3,450 RPM or whatever, so if less efficient then it would stand to reason that they would be pulling more current than they should.

start capacitor, it is a run capacitor. Would it be worth it, in these days of ever increasing energy costs to go out and actually check these capacitors and change them when they get marginal ?

First of all, in the situation you describe, you are correct. If the cap is a known high failure rate component it should have been checked.

My Dad was the refrigeration expert, but from what I understand there are a few tests that can be done to detect problems. The two most common are the temperature drop across the evaporator and the high side / low side pressure differential. The current draw may be an indicator of the health of the system, but comparative readings would probably have to be made.

A little research indicates the start capacitor is always an electrolytic, while the run capacitor is usually a film cap. The most effective test would be to check the capacitance, which would involve more work than checking temperatures, pressures, or even current. Which is probably why the tech didn't do it.

I'm not sure about the capacitance vrs expected life curve, but the odds are it is very non-linear - with the final drop being very abrupt.

PlainBill

There may be certain brands or manufacturing date ranges where the run caps are the most common point of failure. Most of my experience is with older systems, in fact my house has two zones of 36 year old Bryant A/Cs, and each year I expect to be the last for them, but they keep soldiering on. I did blow a compressor run cap about 5 years ago.

But, my understanding of these oil-paper caps is that through thermal cycling they eventually develop pinholes in the paper and the cap goes from completely nominal to shorted within a single power line cycle. So, unlike electrolytics that suffer slow loss of water in the electrolyte, you DON'T get any warning or measurable degradation of the cap.

Jon

e,

Good explanation.

Interesting challange: how to 'stress' test for 'weakness' WITHOUT destroying.

I wonder if low energy HV would do it. At least IF a pinhole were developing. the test would pop through, possibly without killing the cap, then again, if the cap died while you're there testing it, maybe that's better, since you're there and can replace it. Hmmm, rates up there with the car mechanic who pulls on your radiator hose to tear it loose to show you that your radiator hose is aged and will break ...some day.

Run the rated AC current through it an monitor the temperature. That will also have it at the maximum operating voltage.

Why not just replace it if you think it's old enough to fail? I've seen them with bad connections to the foil, and they arced until the heat blew the terminal board off the end of the can. New caps should be film, not oil & paper.

Rubber hoses are reinforced with cotton fiber. If the hose is so bad that he can pull it apart, it's already defective.

cycle.

electrolyte,

In oil-paper capacitors the paper is just a physical separator and the = oil is the dielectric. The oil would refill the pinhole and little change results. They are considered self-healing for this property. ESR from "foil" degradation is the real enemy. They are designed to blow open = when there is excessive heat build up.

?-)

to

te,

om

hen

That means simply monitoring the esr will indicate 'health' of the cap.