Question on capacitor size on Trane AC unit

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pexhouse

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Hi all,

I have a Trane TTX036C100A1 XL1200 A/C unit. I decided to purchase each of the 3 capacitors to have on hand so when one blows I got it ready to go! ...because one blew August last year and it was a $190 service call. ouch
fr_733_size880.jpg

Well, when I opened it up I noticed one was leaking. That specific capacitor was installed with the label non-visible (the other 2 I could read). I went online and ordered the 3 capacitors that were on this unit. Problem is when I went to replace it today (killed the breaker, tested to make sure power is off, shorted capacitor contacts with screwdriver) the MFD is different than what everything says.

This is what is in there currently:


fr_742_size880.jpg


This is what I purchased: http://www.ebay.com/itm/400467149138

Looking at the parts list I took out of the outside unit it appears to me that the 12.5mfd is for the 42, 48 and 60k btu models, while the 5 is for 30 and 36k btu and 4mfd is for smaller.

Also what is in there has some added wording that mine doesn't have ("internally protected", "1000 AFC","SH capacitor")? Looking up sh (self healing) and the others doesn't seem like it's a necessity?

Anyone have a bone they can throw me? I didn't want to put the wrong one in (what I bought) and I go to turn it on and the 4 sides fall off while the compressor, condenser and motor sail off into the air and my neighbor mistakes it for a drone and shoots it down. Not sure if someone has an official book to look this up in...??

Thanks all!

Kevin
 

JerryR

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Kevin,

I feel your pain paying for a capacitor change. I had same thing happen to me at my daughters house. A contactor went out and I got charged $170 for a $10 part. The tech tried to sell me a start cap for another $150 since it read a little low. I said no thanks and ordered another spare contactor and all new caps to keep on hand.

Your unit was manufactured in 1994 so it's getting a little old. The cap was manufactured in 2006 so it's looks like it's not original. I'd go by the parts manual since it is obvious that the cap is not original.
 

DonL

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I agree with Jerry.

If you use the lower value the worst it will do is not work. I would not keep it on for a very long test, if it does not come up to speed in a second.

You can go up in capacitance, but you can not go down if more power is needed to carry the load.

The lower cap value may make it more efficient if it runs.

Is that the Fan motor Run cap ?

If the cap gets hot, something is wrong.

Good Luck
 
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pexhouse

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Thanks for the replies!

Before I give info to the replies above I just want to say I was thinking and did some searching and came across this:
An over or under-sized capacitor will cause an imbalance in the magnetic field of the motor. This hesitation when operating will cause noisy operation, an increase in power consumption, a drop in motor performance and eventually overheating or overloading motors like compressors. The run capacitor should have the exact microfarad (uf) that the motor is rated for.
From here: http://homeenergypros.lbl.gov/profiles/blogs/correctly-sizing-a-capacitor

This is interesting because the outside A/C unit is either on its 2nd or 3rd fan motor (don't remember for sure...I *think* it's on its 3rd). The guy last time showed me the motor had oil all over it and he said the motor just burned up. I wonder if the fan capacitor being over-sized could be what is frying the fan motor??? The guy at the time showed me the voltage coming into the unit was 258V (I saw the display myself so I know he was correct...I told him it's rarely that high, for instance my wall meter right now is showing 116V) and he said that was the reason but still wondering now if too large of capacitor doing it or at least contributing to it... BTW I've been after the power company about looking at the transformer on the pole behind my house...long story short the odds of me dating Kate Upton are greater than the power company changing out that transformer so the occasional high voltage will just be how it is sometimes.
I took a picture of the parts list:

fr_743_size880.jpg



It just says "fan capacitor" so not sure if that is the run or start or what? One thing that is popping in my mind is I wonder if when the fan motor failed if they put in the larger motor (maybe all they had on the truck?) and thus that is why the larger capacitor is in there? Just thinking out loud here.

Even though the unit says it was made 7/94 it was installed 10/97 so that outside unit has only been used since summer of 1998. With that said it's been through several capacitors, 2 or 3 fan motors and the contact switch went bad summer of 2012 (unit would stay on after the inside unit turned off).

Question: would 15 seconds or so be too long for the motor trying to start if it doesn't turn? I turn my outside unit off at the house breaker box. I don't have a breaker box next to the outside unit. It's just some little box on the side of the unit that has some thing that is pulled out. The box cover is hard as **** to get off and put back on so I don't touch it. So with my inside unit going I'd turn the outside unit on, run to the window, it's it's not turning I'd run back to the breaker box and that would take a total of 10-15 seconds.

One last thing I'm not sure about is the 40mfd capacitor that it shows on the list. I assume that is a single? What's in there is a dual run capacitor 40/5mfd. This is what the guy put in last summer. Maybe I just don't understand the lingo and the parts list means a 40/5? Here is the picture:

fr_436_size880.jpg


whew...Now I know what Lloyd Bridges meant in "Airplane" when he said, "Looks like I picked the wrong week to quit drinking..." lol This stuff is confusing.
 
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DonL

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The guy at the time showed me the voltage coming into the unit was 258V


If it really is 258v you should call the power company to change the transformer tap.

"Question: would 15 seconds or so be too long for the motor trying to start if it doesn't turn?"

15 seconds is way to long.

If you turn it off, then back on, it takes time for the Time Delay Relay to reset, That is normal and you should not do that.

That dual cap held by Plumbers Tape is Afro Engineering at it finest, and is not factory.

Good Luck.
 

pexhouse

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hmmm I'm still not sure what is going on. Here's an overall picture with a closeup of the dual-run capacitor wiring that is in there now. There's essentially 4 capacitors in there now when the materials sheet shows 3, right? Is one being combined to make a larger one or...??? That one capacitor (the one on the right in the main picture...currently 12.5mfd but parts list shows as 5mfd) is leaking and needs to be replaced but I'm hesitant till I get a firm grasp as to what is going on, especially since I purchased what the materials list shows (5mfd) and not what is currently in there (12.5mfd).

fr_747_size880.jpg
fr_760_size880.jpg
 

DonL

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The Dual is a Start/Run cap. 40 start 5 run. Normally

It looks like the Black cap was cut out of circuit. And the wire to the other looks to small ?

It looks like the coils need cleaned ?

Good Luck.
 
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pexhouse

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Update:

I installed the 5mfd in place of the 12.5 and it worked. However I decided to just make sure there wasn't a larger motor installed when the motor was replaced in the past (just had a bad feeling about it) and I managed to see the label on the fan and sure enough it said 1/4 horsepower which requires the 12.5mfd according to the BOM list. I maneuvered myself to read the most difficult part of the motor label and it said on there 12.5mfd capacitor. I took the 5mfd out and put the leaking 12.5mfd back in. Went to my local supply house and a 370vac 12.5mfd was $16 so I came home and ordered a 12.5mfd 440vac for $5.50.

How dirty the unit is is the result of the local Trane place (same place that installed the unit) cleaning with the maintenance contract we had on it. It's looking to me they didn't know how to clean it and/or just didn't want to spend the time to do it correctly. Looking at the Youtube videos how to clean these Trane units with their different type coils so I bought a 90-degree wand pressure attachment for the hose and will take the unit apart and clean it from the inside and that will blow all of that off. Hitting it from the outside of the metal panels (what the Trane guys were doing...I watched them) doesn't work worth crap. When I'm done with it those coils will look so clean like they were just installed.
 

DonL

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Went to my local supply house and a 370vac 12.5mfd was $16 so I came home and ordered a 12.5mfd 440vac for $5.50.

Where did you order from ?

You should support your local parts place if they have what you need. I am a old Fart like that.

Make sure you are not buying a Start Cap, They are cheaper than Run caps that are 100% duty cycle.

Good Luck. Thanks for the update.
 

pexhouse

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Thanks for your reply!

Here's the capacitor I purchased: http://www.ebay.com/itm/181765656759

The place that was more expensive is a chain that charges a lot. My friend had told me someplace around here sold it much cheaper but I called him several times yesterday (and stopped at his house) and couldn't get hold of him to find out where that place is so I purchased on eBay. I would have bought in person (wanted to get this done so as long as the price wasn't 3X I would buy it and slap it on). Also the $16 one was only rated at 370v--I prefer higher-rated ones they seem to last longer...

I do have a question, and this may get into that 'afro engineering' that you were/are talking about...lol First the picture:

fr_780_size880.jpg


That is how the thing is wired with multiple sizes just dangling there like clothes on a clothesline. I caulked where the wires go into the box so I won't fill it with water when I clean it but those wires don't look right. I re-wired to the a/c unit box last year with 8ga. The black/gray and red wires come out of the box as 10ga and then are wire-nutted to black/gray and brown 12ga, which you can see goes into the bottom of the contactor switch (previous picture) and then comes back out the contactor top as 10ga. If I had installed it I would have made it one piece of 10ga the entire way to the contactor and tied it along the side so it's not getting sucked into what is like thousands of needles lol. Thoughts?

Might go along with what you said earlier about a wire(s) being too small but I'm not familiar with all of this to know which specific ones you were talking about.

Thanks for all your help. I really do appreciate it. :)

oh and one last thing. In that new picture the large uninsulated pipe at the bottom-center is ice-cold and covered with condensate. I was going to put foam pipe insulation around it and tape it up. Seems that hot air being sucked over it is working against it staying cold...
 

DonL

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That is a great price for the cap.

The wiring for the T-Stat is ok, But it does look like the President or one of his bros wired the power.

Not really, just had to. :eek:

The wires in the unit can be small for short runs.

If those coils are not clean, your compressor high pressure will go up, That is not good for the compressor or gas system. Windex and a water hose works safely. Clean the fan blade too.

Good Luck.
 
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