View Full Version : Motor control in the attic
07-10-2006, 08:02 PM
I have an older unit. The compressor runs without a problem but the motor in the attic is the problem. I shut down the unit at the switch where there is also a fuse (I told you it was older) and when I turned it back on the motor ran .... for a while but would not restart after the unit cooled and shut down. The capacitor looks fine, it is not swollen and the motor did start with it. I removed the contactor which I think is the problem but I'm wondering where to find a replacement. I have been to the web and several sites that offer parts but I do not find a part to match this part number. It is an Essex/RBM and says Coil 24V 60 HZ with what looks like a part number 91-102000-13300. It has five wiring attachments. The other side says Contact rating 12AFL 60ALR 125V on one line and 6AFL 35ALR 250V on line two with 60HZ on line three.
Can anyone give me a hand on a part that would work and is actually available? One side of the part has three wiring blades and the other has two.
Am I even in the right ballpark in looking to replace this particular part?
07-10-2006, 09:35 PM
Why Don't u replace the unit if it is that old , or maybe try using a meter and trouble shoot , it sound like you are doing a lot of guessing.
07-11-2006, 09:09 AM
you are lucky to have fuses! safer than breakers!
better get a pro --
elec can be hazardous
working in attic in summer can be hazardous
guessing about parts can be hazardous to the equipment
07-11-2006, 09:45 AM
Many of the major components of this system have been updated. The compressor unit has been replaced, the condenser unit has been replaced so most of the unit is in good condition. There are only three or four things that could be causing the motor to not run and the contactor seems to be the logical choice since the motor did run and the capacitor looks to be fine. The thermostat is a programable digital and jumping red to green does not statrt the blower motor. I feel confident it is the contactor I just am not sure how these are sized and rated. The catalog companies have them, I just need some guidance on which one is appropriate to replace the model I listed. I can't find a crossreference. I can just go to an AC supply house but I'd prefer to actually learn something here, if possible.
07-11-2006, 09:50 AM
Unfortunately, due to site rules (http://hvac-talk.com/vbb/showthread.php?threadid=1241) we as members can neither discuss technical issues with the general public nor provide DIY guidance.
Thank you for your cooperation.
07-11-2006, 09:55 AM
I can't tell you how but if you have a contactor operating the fan even if the coil was bad it would be easy to determine if the motor was bad, good luck.
07-14-2006, 06:13 PM
Well, I took the contactor to an A/C supply house. The guy knew exactly the part I needed. It cost $8.02 including tax. I installed it and the unit is now running perfectly.
It was a Type 91 relay.
The new part number was 90-340.
Don't be inimidated by DIY but recognize your limitations and always be VERY careful around electricity.
This relay is used in tons of applications and the catalog houses had it as well. I just needed someone who would cross reference it. Evidently it is a well known part and a well known replacement.
To the guy who said he could help me determine if the motor was good. I know you meant well and I read between the lines as far as jumping the wires, but I felt the motor was good so I didn't go there.
07-23-2006, 03:54 PM
i have the same problem, i have an older compresor unit that i want to instal in my house, but the problem is that that relay is disconnected and i don't know how is wired.
can you help me with that?
i have the unit diagram but haven't that part ...
my email is firstname.lastname@example.org
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