matag window air conditioner #m7x06f2d-a

[Guest]

hi. unit fan motor just hums. can turn fan blade by hand no problem. also the switch on the control board is open , i turned the stat down to 66 and waited, switch stayed open.when i jumped the line wire to the overload wire on the switch the compressor started and ran fine. it has a 3 terminal cap , but i'm not sure how to test it. i know how to test a 2 terminal one.the switch i refered to above is the compressor switch. any ideas. thanks.

[kdog]

The 3 terminal cap is merely 2 capacitors in one can (one for compressor and one for fan) - read the terminals and they will be identified on as fan,one as compressor and one as common, bad cap could be causing your fan not to run

Also, the unit may not start if temp/rel.humidity is not high enough but usually you can trick it by warming the anticipator bulb by squeezing it in your hand. The bulb will be either a small capillary or a thermister clipped to the face of the evaporator coils

[Guest]

thanks kdog for the quick reply.yes after i put it back togeather i thought i shuld have heated up that bulb to see if the comp would work, i tried it your way using my hand and the comp. started up fine. i took the leads off the cap and ohmed common to compressor terminal , needle swung all the way to the left of the scale then back, reversed leads , same thing. probed from common to fan and needle swung half way across the scale, reversed leads and again half way across scale and back. seems like cap is ok. do you think this is an acurate test? i think the motor  start windings are shot , what say you.

[kdog]

Give the blade a spin wth your hand (carefully of course) while energized and see what happens. the only sure way is to "sub a known good capacitor" - although I recall Cactus Bob once enlightening us with some pearls of wisdom in this matter, it behooves me to locate it.

I would tend to think that if the motor continues to run when helped to start, that would indicate a capaictor issue

[Guest]

thanks kdog. yes i've  spun the fan many times and it doesn't go ,thats while powered up.

[appl.tech.29501]

Cap. Seems ok by your test...most likely the fan is bad...if you have the schematic you can ohm the windings...is it a varible spped fan?

[misterfix]

I agree that the capacitor seems OK using a multimeter test in this manner, but without substituting a known good one of the correct value, it may never start.  If the value of the capacitor has fallen too low, the motor will not start.  Does it hum when trying to start?

[Guest]

the motor hums the instant i push start and continues to hum. i ohmed the low speed winding from common to low speed wire got 78 ohms. then from common to high speed winding got about 160 ohms. but theirs no where on the schamatic that shows what the resistance should be. the lady i'm fixing it for has an identical  a.c. i might just switch caps to see what happens. the other unit works fine. thanks guys.

.

[misterfix]

Let us know what you discover!

[Guest]

will do,thanks again.

[Guest]

hi guys and gals. i put a good cap in it today and she still no go. the motor is bad. thanks for your help. take care.