Quote:
Originally Posted by #1 tech
sounds like your motor is interaly bad (thermal overload). most any HVAC store will carry a replacement. be sure to take the old one with to get a correct replacement. if it is heat only then use the low speed. if it is heating and cooling then use low for heat and high for cooling. sorry i did not post sooner getting ready for summer at work  |
Thanks for your reply.
It was indeed the fan motor, which I diagnosed without any help from APP.
BTW, are you an appliancepartspro employee ?
For anyone else who gets down this path;
At some point it occurred to me that, but for the new switch, the motor was hooked pretty much directly across 110 VAC. Since I had already replaced that switch ....hmmm, kinda/gotta be the motor, so I did in fact wire it directly across 110 VAC (with the shutdown switch set to OFF) and sure enough I got the same symptoms. The whole lower blower unit is mounted on rails that slide out after removing a couple of small retaining screws. The squirrel cage is mounted to the (1/2 inch diameter) shaft with a set screw to the milled flat, the motor is mounted to the opposite side of the housing with 3 bolts to arms that are held to the motor with a band. All of this is quite intuitive once you have it all out. The 3 arms and retaining band had to be transfered to the new motor, of course I took care to be sure that I got it on STRAIGHT, tight and as close as I could to the same distance from the motor face as it was on the old one. I took the old motor with me and picked what little brain I could find in the local sales counter staff. Well, it came with a schematic anyway. The new motor came with a longer shaft, which didn't matter because it just sticks farther into the fan cavity. I also turned around the 4 thin screws that run through the motor and hold the end plates on, to get their excess length away from the face of the motor where it MIGHT have mattered.
I now (for 2 days) have a very quiet and seemingly efficient heating system. It cycles more evenly, I suspect partly the new motor and partly the cleaning that I did are responsible for this.
About $200 total for switch and motor, the neighbor paid some $5500 to replace his about 5 years ago (same symptoms), but I only found that out yesterday (-:
What to do with the $5300 I saved ?
I'll think of SOMETHING I'm sure, some of it should probably go to converting it to pilotless ignition (hot surface), something I've thought about every few years as the co$t of natural gas has continued to rise.