Help wiring new condenser fan motor


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Old 09-23-14, 06:39 PM
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Question Help wiring new condenser fan motor

First off- thank you for taking the time to read this.

I purchased and replaced the old 5.0 cap with a new 7.5 cap to match the demands of the new condenser fan motor and wired it according to the way my previous motor was wired. I believe I have determined why it is not working but am inexperienced and could use a more educated eye. I've attached a picture of the new wiring diagram and the schematics for my AC.

Old motor has the following wires: brown, purple, black, red

New motor has the following wires: brown, brown/white, black, white, green (chassis ground)

Here is a picture of the AC wiring diagram (old motor on upper right):

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Here is a picture of the new motor's wiring diagram:

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(note: these are large photos. You may need to zoom out)

If anyone has a moment to review these I would *very much* appreciate the help. Let me know if there's any other information you need. I know these schematics are dense but can say a lot more than I can likely tell you about the unit! Thanks very much for reading this!

~L
 
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Old 09-23-14, 07:28 PM
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Welcome to the forums.

Apparently the old fan motor was two speed and controlled by an outside fan thermostat.

Assuming you're using the existing wiring......

New motor black connects to both old red and black wires.
New motor brown to old motor brown.
New motor white to old motor purple.
New motor brown/white gets capped off.

Your new motor states 825rpm. Make sure that spec matches your old motor.
 
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Old 09-23-14, 08:40 PM
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Thanks for the quick reply! Should I return the motor or wire it as you suggested? What would you personally do?

The old fan was rated (EDIT) at 825rpm. I was told that a small difference is okay, but using my inventory/1100 rpm could potentially damage other parts in the unit.

Thank you again for all of your time!
 
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Old 09-23-14, 09:36 PM
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I'm not really sure what the two speed fan accomplishes. Houston, the forum pro, should stop by and he may shed some light on it.
 
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Old 09-23-14, 10:06 PM
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Thanks again for your help, PJmax- Have a great evening. That'd be great if Houston or anyone else can share some knowledge with me regarding the best course of action.
 

Last edited by sacul001; 09-23-14 at 10:50 PM.
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Old 09-24-14, 09:39 AM
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I would remove the OFT from the circuit. Brown and brown/ white on new motor to cap. Black on new motor to BK/BL wire. White wire on new motor to Red wire.
 
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Old 09-24-14, 09:58 AM
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Thanks for weighing in on this, skaggsje. I noticed that 825 rpm 2 speed fans cost approximately $175 more than this single speed motor (local supplier wants $275). What are the drawbacks to removing the OFT and "downgrading" to a single speed fan, other than price? Here is the closest match I can find on Amazon (I hope this isn't against forum rules). Problem is- it's .8 amps over and 1/3 hp.

http://www.amazon.com/Fasco-D936-5-6...productDetails
 
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Old 09-24-14, 10:48 AM
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If I were to bypass the oft- where would you attach white to red? New white directly to open T1 terminal? The owner would rather entirely bypass OFT-A than attach new black to red at OFT-A and likes the idea of eliminating another variable that is OFT-A...

Obviously I am not getting paid for this, just trying to learn more about central heating and air in the process of helping a family member save $$$.
 

Last edited by sacul001; 09-24-14 at 12:23 PM.
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Old 09-24-14, 12:23 PM
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I'm not a pro, however I suspect that the advantage of the two speed, thermostatically controlled fan is one of noise. When it's warm but not sweltering, the low speed should be sufficient to keep the compressor cool. When it gets really hot, the thermostat will cause the fan to kick up to high speed to provide better cooling. Obviously, the slower fan speed will make less noise and will accommodate most of the daily operation.

You mentioned 825 rpm. Is that the low or high speed? If you go with a single speed motor, you should go with one that is equivalent to the higher speed. It will be a little noisier, but will be required to keep the unit cool on really hot days.
 
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Old 09-24-14, 12:47 PM
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Old motor only reads "825 rpm". The old motor's label did not even say "2-speed". It just reads 1/6 hp / 825 rpm / 5.0 cap / 370vac / etc. Thank you very much for weighing in on the matter. All opinions are appreciated and I will post final results/course of action.

My understanding is that it decreases noise, saves energy, and decreases rh by allowing longer run time.

In the meantime I may take the old motor apart and see if I can pull/replace bearings. You know, just for sh**s and giggles. I'll also be cleaning the coils with a foam coil cleanser. This should help tremendously as they're not even visible in most places.
 
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Old 09-24-14, 01:16 PM
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The Amazon motor shows 825 rpm, so I assume that is the low speed. I have replaced alot of motor's but don't recall every seeing a 2 speed on a condenser. I bet Houston has seen this and I hope he stops by tonight. My guess is when outside temp rises above set point of the stat the motor goes to high speed.

Really dirty coils are hard on the fan motor.
 

Last edited by skaggsje; 09-24-14 at 01:19 PM. Reason: added info
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Old 09-24-14, 01:32 PM
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Interesting- thanks very much. If this is the case and low= 825 / High= ~1000, perhaps I could return the new motor and simply replace with my 1100 rpm motor w/fan blade left over from a 2012 package york unit of mine. Or perhaps 825 is max speed and the "low" setting is regulated via another factor such as voltage (like a DC computer fan)? I'm anxious to hear what Houston thinks
 
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Old 09-24-14, 02:22 PM
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According to the wiring diagram it runs on high or low speed. You would have to have a variable speed motor to to speed it up and down.

Just curious, how old is the unit? If you could post make, model, serial number I could find out. I'm thinking maybe the old motor might be a replacement to the original motor.
 
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Old 09-24-14, 02:47 PM
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EDIT: I understand you'd need a variable speed motor, but wouldn't they spec both high/low rpm if the high/low setting was predefined by a given motor and not governed via the OFT? I'm unable to find any replacement motor that specs two different rpm.

Its a 2002 "Allegiance 14" by American Standard.

Here's the sticker on outside of unit:

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And here are two shots of the old condenser fan motor's label (This is all the writing on unit/ taken through grate prior to removing motor):

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And here is a link to the updated model/ same motor:

OEM Upgraded Emerson 1/6 HP 230v Condenser Fan Motor K55HXJAE-8958: Electric Fan Motors: Amazon.com: Industrial & Scientific

BTW, I'm relieved to hear that I'm not the only one taken off guard by the presence of a 2-speed motor. When I purchased the replacement I simply went by the printed label, wrongfully assuming it would state 1/2 speed.
 

Last edited by sacul001; 09-24-14 at 03:16 PM.
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Old 09-24-14, 04:19 PM
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A 2 speed condenser fan motor is great for keeping the head pressure up when you try to cool a hot house on a cold day.

Old GE condensers used to use them and Trane bought out GE in the 80's.

If this was an old GE condenser I would definitely use a single speed motor (and have many times)but with a 14 SEER unit I would use another 2 speed if it were my house.
 
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Old 09-24-14, 06:13 PM
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Thanks, Houston! I just boxed up the new motor and will return it tomorrow.

Would this fan be a suitable replacement? If so I will order it tonight.

"Fasco D936 5.6-Inch Condenser Fan Motor, 1/3 HP, 208-230 Volts, 825 RPM, 2 Speed, 2 Amps, Totally Enclosed, Reversible Rotation, Sleeve Bearing" $144
 
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Old 09-24-14, 06:25 PM
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It looks like it should work. The strange thing is that motor is sold all over the internet and not one company has the two speeds listed.
 
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Old 09-24-14, 06:36 PM
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Fasco D936 5.6-Inch Condenser Fan Motor, 1/3 HP, 208-230 Volts, 825 RPM, 2 Speed, 2 Amps, Totally Enclosed, Reversible Rotation, Sleeve Bearing - Electric Fan Motors - Amazon.com

Does your motor mount with 4 bolts sticking out from the lead end as shown in the picture?

Seems like I remember some models that had predrilled holes that you tapped the 4 black fine thread screws into.

I didn't see the frame size of the fasco motor but I will see if I can find it.

I have always use OEM motors for 2 speed applications.
 

Last edited by Houston204; 09-24-14 at 07:07 PM.
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Old 09-24-14, 06:37 PM
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You're right... am downloading fasco's catalog right now to make sure they actually manufacture 2 different models.
 
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Old 09-24-14, 06:42 PM
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http://www.amazon.com/Upgraded-Ameri.../dp/B00C9J0VGS

It appears that this condenser does use the 4 existing bolts for mounting.
 
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Old 09-24-14, 06:56 PM
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The old motor had predrilled holes and 4 screws. The new motor I just boxed had 4 bolt-threads sticking out that I mounted with (4) nuts and washers to grill. The grill on my AC accepts both mounting options- but kudos on the sharp eye! I just emailed amazon to see if they can verify 2-speed ability on the fasco. It's the most affordable I have found, thus far, from a reputable dealer.
 
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Old 09-24-14, 07:06 PM
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FASCO - D936 Condenser Fan Motor - Condenser Fan Motors - Motors

That price sounds too low to be a 2 speed motor. This site lists the Fasco D936 as a single speed motor.

Looks like Shortys has the 2 speed MOT11233 for $238 but I see nothing about freight charges. That beats Amazons $269.99. and ebays $259.99 but they both offer free shipping.
 
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Old 09-24-14, 07:13 PM
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Yeah, I thought that was too good to be true... Fasco's catalog also lists the d936 as a 1-speed. Even stranger, Amazon lists Fasco as selling both a $138 1 speed and a $145 2-speed... Am eagerly awaiting their reply, haha.
 

Last edited by sacul001; 09-24-14 at 07:33 PM.
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Old 09-24-14, 07:26 PM
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I see the MOT11233 cheaper on a couple of other sites but I have never heard of them.
 
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Old 09-24-14, 07:47 PM
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Is it okay to decrease the hp? Old motor was 1/4 hp & 1.2 amps. MOT11233 is 1/6 and (?) amps.
 
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Old 09-24-14, 08:13 PM
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No, we cannot decrease horsepower.
I must have incorrectly typed X70671887010 to get that part number.

I'll try again...
 
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Old 09-24-14, 08:16 PM
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The 1/6 hp motor came up again?

It is strange that your condenser nomenclature lists a 1/6 horsepower motor but the motor clearly displays 1/4 horsepower?

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Old 09-24-14, 09:23 PM
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Yes, sir. My search brought up a 1/6 hp unit with no defined amperage. Wow, you're right. The unit does indicate 1/6 hp, but my failed motor reads 1/4. Thank you for noticing that and taking the time to help.
 
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Old 09-24-14, 09:35 PM
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I'd like to see an FLA rating of 1.4 Amps as shown on the condenser nomenclature.

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Old 09-24-14, 10:12 PM
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Thank you! The last AC tech replaced it with a motor .2 amps UNDER rating, eh?
 
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Old 09-25-14, 07:35 AM
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I'm off to buy a 1.4 amp 1/6 hp 825 rpm 2-speed motor from one of the 6 local HVAC suppliers. If anyone has advice on using foam coil-cleaner in meantime, feel free to send it my way.

Many, many thanks to PJmax, skaggsje, bob14525, and Houston204 for taking the time to help a newbie repair an old man's HVAC. I will update with results after installation.

~S
 
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Old 09-25-14, 08:58 AM
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Hey Houston, does the OAT switch the motor speed?
 
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Old 09-25-14, 11:32 AM
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His diagram lists it as an OFT. Outdoor fan thermostat.
 
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Old 09-25-14, 04:48 PM
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Yes- the OFT is what cycles it under 825 rpm, the max speed [according to staff at my local American Standard dealer]

I returned the motor, then went to the AS dealer that "only sells to certified HVAC tech". They cut me some slack and/or had pity- then not only sold me the motor, but sold me their last MOT11233 for only $175! "Plug and chug" wiring, as my father would say... After installation, however, I still only heard a faint "hum" and unit behaved just as it had with the single speed motor, prior to any repairs whatsoever.

So, assuming palmetto bugs (smokey brown cockroaches) had shorted out the 24v contact coil, I replaced it as well, then wired accordingly (their feces/dried oothecas were littered everywhere within unit)... After taking the old contactor coil apart I found they had indeed shorted out the back half.

It is now fully functional! Thanks again to everyone that helped here on DIY forums!

Replaced parts:

(1) capacitor
(1) compressor contact coil
(1) factory 2-spd fan motor
 

Last edited by sacul001; 09-25-14 at 04:53 PM. Reason: spelling
 

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