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Air Handler blower won't start - hum from transformer?
Asked Jun 23, 2009, 07:38 AM
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16 Answers Air Handler: Armstrong 40528C093 Transformer: Basler Electric BE321640GEK (photo attached) - a quick web search found it here: Amana, Goodman Transformer 208/230 Volts 24 Volt Secondary: Best Buy Heating and Air Conditioning (note: although that webpage shows the primary voltage as 208/230, the sticker on my transformer actually shows it as 208/240 - they both match in showing the secondary as 24V and the sticker on mine also indicates 40VA) Blower control? / time delay module (photo attached): Heatcraft FTC8-ECO3 or Armstrong P/N 39971B001 Situation: (Note: outside unit is running properly.) Turn on thermostat and sometimes air handler blower doesn't start. When this happens, I've opened the control panel section of the air handler and a very loud hum is coming from, I presume, the transformer. I say I presume because the module listed above is right beside it so it's hard to tell which of them is producing the hum. I tried moving the blower a few times and that did NOT result in it starting up, so I am guessing it's not a dead spot. Additionally, it turns freely so apparently it's not a problem with bad bearings. Lastly, a bit of history... Last summer it first started this intermittent problem. The air handler is in an attic storage area and the problem seemed to happen more often in the afternoon (so much hotter in there). I thought perhaps the transformer was overheating so I attached a spare PC CPU heatsink to it and that seemed to solve it. But now it is happening again even in the early morning when it isn't hot in there. Turned the blower motor a half turn again (it still turns freely), but still didn't start. Left off the circuit breaker for a while (half hour to an hour) and it did start after that. At this point, my best guess is the transformer is going bad, but I am definitely not an HVAC or electrical expert. Again, the transformer is immediately beside that 90 second fan off time delay (is it also a blower control?) module so I can't be certain which is the source of the hum. If it would help, I recently got a digital multimeter. I'm only just learning how to use it so I'm happy to test anything but please tell me what/how bearing in mind I'm new to it. Thanks in advance! |
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| Was there anything printed on the side of the capaitor? May need to pull the mtor to see the caps mf rating. The motor will say what size is needed. Blowers take anywhere from 5 to 15 usually for residental. I will try looking up the system and see if I can find the cap it needs. | ||||
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| Thanks for all your help. It's seems at this point it must be the motor. Since this is an intermittent problem, I'm reluctant to replace it unless I have to. So, I checked the wiring and as I expected the motor is wired to run at high speed. I expected this because it is rather loud. Since this unit only serves 2 bedrooms and a bathroom, low speed (900 RPM vs 1100 for high) seems adequate and will have the side benefit of being quieter. And correct me if I misinterpreted what you said earlier, but it seemed like each speed has its own winding. If that's the case and there's an issue with the high speed winding then possibly the others could be fine? Therefore, I hooked up the low speed wire in place of the high speed all is well so far. Will just have to wait for a while to see if it continues to repeatedly start as it should. If I've overlooked anything or misunderstood the windings issue, please let me know. Thanks again for all your help and insight. | ||||
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| Hum from transformer usually indicates that you you have lost 120v feed to system on 1 side or the other .....a complete 230v feed may not exist. Check that you do in fact have 230v to your system. I have found that a bad breaker or corroded conductors (cables) are your most likely problem. | ||||
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| I just had the same problem. It turned out to be a bad capacitor. It is recommended to replace the capacitor anytime you replace a motor. I would try replacing the capacitor first. It is a lot cheaper that a new motor. If that does not fix the problem then you can get a motor. No harm, no foul. The slow start/no start of the motor is a common symptom of a bad capacitor. The motor is not getting enough voltage. The capacitor increases the voltage like a transformer. It will boost it to almost 400 volts, depending on your unit. | ||||
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| I am having this same problem. After about five cycles of off and on the blower wont turn on. I dont think its my thermostat cause I tried jumping the wires when the fan would not start. The blower only has two speeds. I switched it from slow to high today to see if it fixes the problem. I used a voltmeter on the transformer and it seemed fine. I also had an ac guy check the the capacitor with a voltmeter and he told me it was ok. the evaporator coils freezes when this happens. I am scared it is going to damage the compressor. I hope it is not the control board cause I dont have the money for a new board/relay. | ||||
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