Need help-Window AC unit down...

[ModRob]

I have an old Gibson window unit that has acted up on me and would like to attempt to repair it if at all possible.<p>The unit is powered by 220 volts, and says on tag that it has a 16,500 BTU cooling rating. Last summer the motor started acting up; I oiled it up good (it has two oil ports on each end of the motor) and it worked fine all summer. Now this summer when switched on, the motor turns smoothly, but much slower. Too slow to really put out any air flow. When the switch is engaged to either low or high, there is a very slight change in the speed, I think. And the shell of the motor gets very hot. The compressor seems to be working fine and switches on ok.
I had started working on removing the motor, but the terrible amount of rust and corrosion has me hindered for-the-moment. With that, I thought I'd ask for further info.<p>The unit has a very large cap with three 4-spaded heads on the top of it for the wiring. I'm afraid of this thing..lol...so I'm asking for details on how to proceed. Is it possible that this cap has gone bad and causing some problem with the motor's speed? Here are the details printed on the side of the cap:
JARD
CLORPHEN A
25+3 UF 370 VAC
D3725/3 A24-G
Y504166-17<p>Anyone able to give me info on how to proceed?
Thanks,
Tim

[jollyrgr]

I have been fixing fans ever since I was a little kid. Have you tried to see if the fan runs normally on the FAN setting? Make sure the compressor is not dragging the voltage down and causing a local "brown out" to the motor. But let's assume there is a problem with the fan.<p>First, when you spin the fan by hand does it feel real smooth or does it take some effort to spin? When you do spin it by hand, does it quickly stop or turn a few revolutions first? The fan should move without much effort. If it does move real smooth, possibly it's the capacitor.<p>Should the fan NOT move smoothly, you might try taking the fan motor apart and cleaning the insides. The shell comes off quite easily and you know how to do that part. The window units I've dealt with have some sort of "stand" that is mounted to the base of the unit. The stand then clamps around the motor. Disconnect the wires going to the fan. There will probably be five wires; neutral, capacitor START, high, and low speeds. Label the wires carefully or draw some sort of diagram or list saying what wire went where. Disconnect the wires and remove the fan, noting which way the motor was mounted in the holder. It might be easier to remove the fan blades first. There is probably a squirrle cage blower for the inside fan and a standard blade fan for the outside blower. <p>The fan will likely have four long screws that fit through the motor to hold the shell together. Before removing any of these screws mark the shell with a permanent marker or other "permanent" means so that you can line the two halves together again. Your motor may have "endcaps" instead of being a two part shell. Adjust accordingly. Now remove the screws and GENTLY pull the two sections apart. Slide the bearings off the shaft being careful not to lose any of the spacer washers that sit on the shaft against the armature and the shaft bearing. Examine both bearings carefully. If they are real shiny and dry you are not getting oil to the shaft. (The mention of the word RUST leads me to believe that the oil journals may be plugged up.) Get a parts cleaner (DO NOT USE GAS!!!) and clean the bearings. WD-40 works great for this type of clean up job. Clean the spacer washers as well. Soak the fiber sponge around each bearing with a good motor oil. In my opinion oils like "3 in One" are JUNK. I use standard 30 weight engine oil (the stuff you put in the crank case of internal combustion engines) in an oil can to lube motors and such. Coat the shaft well, being careful not to put oil on the location of where the blade is on the shaft. Lube the washers and reassemble them on the motor shaft. <p>When putting the shells (or endcaps) of the motor back on, be alert to the fact that the bearing will "gimball" on the shaft. In other words the bearing is like a ball that rotates inside the shell. Make the shell perpendicular to the shaft as closely as possible on BOTH sides of the motor. Spin the shaft to make sure it stays free. Push the two halves together being careful to remain even on both sides as you push them together. Do not push them home just yet. Insert the screws and make sure that the sections line up correctly and the screws do no bind when being inserted. Tighten the screws and nuts finger tight. Then tighten each screw a turn or so being sure to alter to opposite corners so that you do not warp or distort the two halves (endcaps) and misalign anything. Frequently turn the shaft to see that it remains smooth.<p>Reinstall the motor and blades and give it a test. Hopefully you will be a cool guy.

[ModRob]

Thanks for the reply.
I can tell you that the motor acts the same whether in fan mode or "cool" mode. And it does spin nice and free by hand, without any dragging...

[High4Volts]

I would bet it's the motor capacitor.

[rshayes]

Since the unit is old, and somewhat corroded, it is also possible that some of the connections are either open or high resistance. Faston type connectors are often used in this type of equipment. They can lose contact pressure with age, or may make poor contact due to corrosion.

[ModRob]

So I think before I try and "destroy" this thing more trying to get the motor out, that replacing the large cap might be worth it. Again, I'm afraid of these things, as I've read over time that they can hold lethal charges. How do I go about "tiptoeing" around this unit? Like I said before, there are three connection areas on the top of the cap; each area consisting of four spade-like lugs that wires with female lugs slide onto. And then, where do I begin to look for a cap like this? I'll check around with some repair places around here; maybe there are some junk units that might have a good one or two...<p>Again, thanks for your help...

[Edd]

ModRob:
Looks like you have found yourself a run capacitor and as for worrying about retention of charge on that unit, it is discharged almost as soon as power is depleted from its circuitry. However,if you totally insist........place a screwdriver across its term sets when there is no power, see no sparkee. With your water splash and rust situation, I think you have developed shorted turns in the motors winding(s) thus your excess current consumption and heating. If you have a clamp on ammeter , a sample current reading compared to your specs should reveal this. As far as the motor run cap I don’t suspect that........less robust motor start caps.....however...thats another story. If you happen to have a newer generation multi purpose dig voltmeter, it may incorporate a cap test scale/function. At the least it will have an ohmmeter function where the cap can be tested for short....which I don’t expect in any way, since that motor would really be humming. Seems like others covered the mech aspect well, which should not be your nature of problem with a free wheeling rotor. <p>73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
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[ModRob]

Wow Edd..you always come through for the folks on here. (and the other guys do too) After thinking about your text, it makes perfect sense to me. I was hoping that it would be something easy to get to like that cap...haha...no such luck. I can't for the life of me begin to get the motor out. I finally got the set screw in the basket-cage fan at the back of the motor loose, but it won't budge off the shaft, even after terrible amounts of WD40. From what I can guess, it looks as if the frame that surrounds the motor on the front and back sides of it have to come away with the motor. I can't seem to see where they are attached to the bottom floor of the unit, but there is so much loose rust down there, it's hard to tell. At this point, I can't get much movement to happen by pulling on it. It looks impossible to get the front circular fan and the basket fan off because there are radiator units right beside them...<p>Yes, it's probably a lost cause, but my landlord says he has a motor for it, and the darned thing does cool very well when it works. Plus a model of the same size is a lot of money if not totally necessary...haha...<p>Thanks again guys.<p>Tim

[Edd]

HEY!.....I just realized I don't know what a ModRob? is.......another cryptic little psuedonym to mull over in the mind.<p><<I finally got the set screw in the basket-cage fan at the back of the motor loose,>>
Double check down inside its collar within its tapped captive hole and see if possibly they didn’t double set screw it, as is sometimes commonly done on equipment subjected to a vibrational environment.
Otherwise its mo-mo-mo W-Dee 40 along with a judicious application of pinpoint propane torch heat to the fans collar with a simultaneous chilling of the motor shaft along with some tap-tap- tapping of that collars end on its longitudinal axis , as in respect to the length of the motor shaft. Sometimes its tough tough work. Heck at times I have had to hacksaw off the motor shaft between the stuck collar and the motor proper….since I knew the motor itself was history. Then a placing of a hardened deep tool socket on the short end of the shaft resting against the collar and backed up against a vise/or/concrete, then the shaft can be tapped loose from the collar without the collar being unduly subjected to any deforming.
<<From what I can guess, it looks as if the frame that surrounds the motor on the front and back sides of it have to come away with the motor.>>
If it incorporates the conventional NEMA 48 motor and its support bracket/basket, look at the end plates and confirm the half round support ends with half round companion spring steel clamps that come down encircling the large O / hex rubber(neoprene) damping donut and then clip over side protruding dogs on the top support tip apexes. It takes the deft application of a pair of plier ends to pull one of the spring bottoms out and away and then the whole tensioned spring will pop upwards and typically FLY loose.
<<It looks impossible to get the front circular fan and the basket fan off because there are radiator units right beside them>>...
Would that be interpreted as the the over condenser pulled chilled air being driven by a rotary squirrel cage configuration of blower vice a conventional 3-6 bladed fan .?
AC longevity….???... in my woodwork shop window I am still running a ’64 Fedders 2 1/2 ton unit. Three blower motors being required within that period of time, all salvaged functionally….for free from other discarded window units. That big Tecumseh compressor just keeps a purring.<p>Aside: Jolly Roger: a magnificent tutelage on the fine mechanical intricacies/aspects of motor disassemblage, covering almost every quirky little nuance one would typically encounter.
Might add a situation of very,very initial minor onset of scoring of the motor shaft within the porous bronze bushings running area. A radial axis dressing down of that affected area within the motor shaft, via clamping the extracted rotor shaft end in a electric drill and using it in ones lap lathe style to dress down the affected shaft area with oiled 800 grit Wet’n Dry.
Almost all my encounters of end cap oil reservoir pads encircling the bushings were multilayered felt pads.
On very small motors my favorite oil medium is automatic transmission “fluid”, it certainly proves itself well in the high temperature subjected to within its automotive use as well as its phenomenal anti-gumming characteristics.<p>73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
[email protected].........(Firewalled-Spam*Cookies*Crumbs)

[ModRob]

More good info Edd..thanks again. I think the motor fastening scenario you mention is a little more than what this appears to be. This would seem to be just three mounts, with a nut visible on the outside, and rubber bushing, and the stud itself. I can't see where it's any more complicated than that...<p>I'm tackling this a little every day or so...I'm thinking it's going to be a real bear getting that whole assembly out, but I think that the whole motor and it's front and back "walls" have to come away from the bottom "floor" of the unit before it can come apart...I for the life of me can't seem to see any other way. Now, where's my extra big crowbar...?....<p>and "Modrob" is for my dated, seventies hairdo (Mod) and "Rob" is short for Robert...
So there you know the...."rest of the story"...
Good day, I'm Paul Harvey......<p>Tim

[ModRob]

Ok fellas...I've finally been able to remove the motor from this unit. And the basket fan along with the five-blade fan are off the shafts as well (several days of soaking with WD 40..)<p>I've opened up the motor just to observe. It came apart with the above-mentioned four bolts, but the case comes apart as pretty much the whole shell on one end; a flat end cap on the other. Along with the flat endcap came the shaft and an armature different from what few I've seen; it's pretty much a solid piece. The field inside the big cap looks to be ok (no obvious abnormalities). There are four wires that leave this unit, and a small ground wire that attaches to one of the casing bolts.<p>Now that this unit is out, is there a way to "test" it to see if an obvious malfunction? My landlord says he has a motor that should fit--if not he'll buy one--but I'd like to see know for sure before going that far. <p>Until the next step....

[Edd]

Well, now I see that I had omitted one tidbit of data on my previous post that might have eased matters. Specifically, a tip on the freeing of the setscrew(s).
Agreed that the application of WD-40/menstruating oil to the problem area is of great import in permeating into the deepest crevices. With the wizardry of chemical additives mixed within our car motor oil , some of them really do work down into metal pores even more thoroughly . So I initially get max penetration with the lower viscosity WD-40 and then place the item so that gravity can then drain back out as much of that as is possible along with a little boost by wicking out by touching toilet tissue to the gravitational drain area. Optimally then, if you have it, a final blow out/off with an air hose. Then place drops of 30 wt motor oil back on the same area , but mechanically reversed so that downward gravity feed can aid in getting the new oil medium into the problem area. However this time the oil will make a capillary transmigration with the WD40 and work down into the same depths that the WD-40 initially penetrated. This has always worked great for me.
Now, back to the torn down motor, any visual evidence of burnt winding wires, or that distinctive odor of same….that is if your olfactorys are not overcome by the strong reek of WD-40.
Also, you must be more familiar with DC motor/generators/alternators and with their contact media than with fixed split phase,etc electric motor construction.
Well you are now down to the stage of teardown where, if you were a motor rebuilder, you would enact a test of all of the stators poles by the use of what is called a “growler”, which is basically just a small strip of transformer laminate. The stator winding (case) is powered up at a reduced voltage due to the rotor not being in place and then the strip is walked around the circumference of the internal adjacent pole pieces. There will be a buzzing sound as the strip is moved laterally and one can differentiate the absence or disparity of magnetic strength when moving between adjacent segments, both aurally by its chatter/”growl” and by manually feeling the magnetic pull on the strip. A good unit will be uniform between every pole set. I personally like to use a pocket screwdriver with a magnet encased in the end of its plastic handle…it is a quantum leap in sensitivity. Since you have done the max work to date seems only right to make the owner at least spring for a new fan motor. If you should be so lucky to have one locally, WW Grainger has always been my source.
Good Day……a la Paul Harvey<p>73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
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<p>[ June 23, 2004: Message edited by: Edd Whatley ]</p>

[ModRob]

Again, thanks Edd. Your insights are always a joy to read, although many times a bit over my head...haha...I've always been a "jack-of-all-trades" kind of tinkerer. I've been awfully lucky at fixing things with my limited knowledge.<p>I find your description of the "growling" test very interesting. I'd like to see that done just to satisfy my curiousity. "Pocket screwdrive with magnet encased in the middle of it"?? Is that a special type of screwdriver, or just a normal magnetic one? And then, how would I go about supplying power to the case unit? There are four wires the are emitted from the motor. And how much power? I understand how the test is done though after that. It's probably too much for me to get into, but again, it would be interesting to see for myself how the motor acts.<p>Yes, the landlord says he already has a new motor that should fit. If not, he'll buy a new one. If that don't work, he'll just get a unit. But this is such big unit that works very well, it would be a shame to not give it a try. I do work like this around the house for him--it keeps my rent more manageable, as the house is surely worth more...<p>Thanks again Edd...<p>Timbo

[Will]

My ten cents worth - I'm no expert on these things so what I say may be mostly BS - Firstly - you have said that the fan/motor assembly turns over quite freely - which eliminates mechanical problems- secondly - this may show how little I know - I thought that free running low/zero start applications for single phase motors usually didn't have RUN capacitors - only START capacitors - Where you only have a start cap there is always a switch of some kind to switch out the cap when the motor is up to full speed - sometimes the switch is a timer but mostly it is a centrifugal switch on the fac shaft - when the motor gets up to speed it simply cuts out the winding. Single phase motors have little or no starting torque available because, being single phase, they have no intrinsic rotating field - this is furnished by the capacitor putting one part of the motor winding out of phase with the other. If I were doing it I would check for the presence of such a switch and see if it was working - then I would disconnect the capacitor, put an AC ammeter in series with it and then try to strat the motor - see if you have a capacitir current. My suspicion is that you have not otherwise the motor would be running.