Burnt Electrical Smell from ICP Air Handler Model# BMM036XKA1

[Brad Anesi]

I've got a 2-zone conventional central air system with Heil compressors outside and ICP air handlers in the attic. It's about 30 years old. Upstairs zone works fine. When I went to first use the downstairs zone this year, very quickly I got an acrid, burnt-electrical smell from the downstairs vents. Obviously, I immediately shut the system off.

The next day (once the smell had cleared), I tried to do a short running of the system, and the fan didn't come on at all nor did I smell anything. The breaker at the house panel never switch off, so perhaps there's some sort of breaker at the air handler, or maybe something just burnt through and isn't even making a connection at this point.

I need to head up to the attic and see what I find. My best guess is a seized up motor, but what else should I be looking for? I can't find an exploded diagram on-line but here's a listing of the most common parts....

https://www.repairclinic.com/ProductDetail/1290190

Appreciate any suggestions...

 

[Brad Anesi]

Just doing some more digging on-line, this video points to the transformer and/or circuit board as likely failure points...

 

[Sponsor]

 

[Fitter30]

Bad motor, burnt wiring ( loose connection) or a bad capacitor..If replacing motor don't go by hp alone look at name plate amps. If replacement motor has less amps even .1 either pick a different motor or go to next size in hp and replace capacitor even if it's the same size. If the motor has ears for mounting to housing they make a retro kit to add ears. Manufacturers play with rated hp but not name plate amps.

 

[Brad Anesi]

Bad motor, burnt wiring ( loose connection) or a bad capacitor..If replacing motor don't go by hp alone look at name plate amps. If replacement motor has less amps even .1 either pick a different motor or go to next size in hp and replace capacitor even if it's the same size. If the motor has ears for mounting to housing they make a retro kit to add ears. Manufacturers play with rated hp but not name plate amps.

Good call on the bad capacitor! I had already removed it when I took the pic, but you can see in the background that it scorched the fan housing it was attached to. Motor turns effortlessly and still looks new, so I'm hoping that's fine. It would appear that the part has been superseded by capacitor part# 1094240, available here...

https://www.repairclinic.com/PartDetail/Run-Capacitor/1094240/2767789

Do these just tend to fail on their own rather than being a symptom of something else failing? As you can see from the additional pics, it appears that the Blower Delay Control IC and transformer look to be fine.

Thanks for the input - greatly appreciated.

 

[Jeff H Young]

capacitors commonly go bad , id throw 11 bucks at the problem even though i hate to take chances . should be able to test it easily and if bad I would buy a new. Im not much with electricity but wouldnt hesitate to spend 11 bucks I dont have anyone to come fix it for free. Hope whichever way you choose its back running soon

 

[Brad Anesi]

capacitors commonly go bad , id throw 11 bucks at the problem even though i hate to take chances.

That's the approach I was leaning towards. Just figured I'd do a little detective work first and see if there was a significant likelihood that something else was failing and the failed capacitor was more a symptom rather than simply being the root cause itself.

I also want to head back up in the attic and see if the other air handler still has the original capacitor. If so, I'd order two and proactively replace that one too.

 

[Fitter30]

Any brand capacitor, any shape as long the mfd and the voltage rating is the same or higher can be used if it will fit in the space can be used.

 

[WorthFlorida]

Plastic housing cap? Never seen one. The replacement probably be all metal housing. On the outside compressor units usually will have a three pole cap. One is common, one for the compressor, the other for the fan motor. If it all metal, the top part of the cap will bulge when it goes bad but can also swell a bit and still be good. Plenty of YouTubers out there with pictures.

 

[Brad Anesi]

Plastic housing cap? Never seen one. The replacement probably be all metal housing.

Yep, the updated part is indeed in a metal housing. I'm guessing ICP had issues with these caps which is why the original part is no longer available. That's also why I'm going to check my other air handler to see if it might have already had the cap replaced. If not, it will be.

 

[Brad Anesi]

Good thing I didn't just blindly order two of the capacitors. I only realized today that the upstairs air handler is a slightly smaller unit, ICP Model# BMM024XKA1. It uses a different cap, original part# 1200020, 7.5Mfd, 370V.

The original cap is still in place, and yes, it is the same, Made in UK, plastic type, so I think it would be a good idea to replace it. Do the Mfd values need to match, or will the 12.5M spec'd for the larger unit work fine?

 

[Reach4]

You may find https://www.supplyhouse.com/Motor-Run-Capacitors-19702000 of interest. This one gives different capacitance, depending on which terminals that you use. https://www.supplyhouse.com/MARS-12...Oval-Universal-Replacement-Capacitor-370-440V

I don't know how closely the mFd numbers need to match.

 

[Fitter30]

UF is the same as mfd
12.5 UF = 12.5 mfd

 

[WorthFlorida]

Inside the air handler, usually on the back side of the door will list components with a diagram.

 

[Brad Anesi]

Got back up in the attic this morning and replaced the capacitor. We now have a working air handler again for the cost of a $12 capacitor! The new cap' was shorter than the original and bigger diameter but I was still able to use the original bracket by just using some longer sheet metal screws.

Thanks for all the help here. I can only imagine what this would have cost if I brought in a HVAC tech.