Gas and Oil Home Heating Furnaces - sporatic working blower?

a repairman was called for this problem, thought it was fixed but same problem and too difficult to come up with another service charge for nothing at this time. The air handler unit I have that sits up on a stand in corner of living area at times will sound like it sticks, a humming like sound but the blower wont come on.I will turn the thermostat off and wait till everything shuts down and turn it back on. It will then start up and maybe keep on working for a long time. I cannot leave the house as am afraid it will do this when away so I turn it off during the night and when away. I am always afraid of electric so will not mess with it. The air handler is maybe 6 or 7 years old it makes a loud noise when the blower kicks on and it does have one of the old thermostats not the digital kind.any suggestions would be appreciated thank you

sound like more likely weak starting capatior or interal starting switch is weak one of the two depending on the type of blower motor is set up.

you may have to get the HVAC guy to recheck the capaitor on the motor or starting switch this is the safest way to do this because it kinda little over the head for average DIY to deal with it

You have a motor bracket that may be broken or mis-aligned causing the blower wheel to get hung up inside the blower wheel housing. If it makes a loud noise it's definitely mechanical. When the blower wheel gets hung up, of course the motor starts to humm. "somebody un-stick this blasted hung up blower wheel before I go of on my internal overload ". Two cents from a HVAC tech hope this helps. Of course if your "loud noise" is a squeeky noise then motor bushing would be the problem

This makes sense to me, I cant believe the repair man didnt check this while here, I sure m ade it clear what was happening.
I had taken off the side panel at top and could see one wire looked burnt, and pointed that out to him. He replaced that wire, never looked at the bottom where blower is then preceeded outside to compressor where he replaced relay switch, checked freon and hosed out ; Came back in turned on at thermastat and of course it worked as this it does, just will take a fit and not turn on blower fan!as I said before I will turen off at thermastat wait till all shuts down and click back on; it will then start up okay again. However it makes one paranoid not knowing when it will happen again.Is this a very expensive repair for one of little means not to mention old and handicapped! also if one wanted to check out the condition of the blower I assume it would have to be turned off at fuse box not thermasta alone? Thank you

Pulling out a blower motor housing on most residential upflow furnaces (the kind in a closet) ussually takes me about 15 seconds to remove for inspection. 1) disconnect 3 or 4 wires, take out two 5/16 sheet metal screws and pull. The whole assembly (if it's supported on 2 slide bars) pull right out) You can also unplug the unit and reach into where the blower wheel is and give it a good spin. If it hits the housing well then___ you have one of two conditions that I described. Price I would guess anywhere from 120 bucks (if the repairman is a decent fellow and your motor is O.K.) to 275 or more. The bigger the ad the more you will pay. (a lot of Air Conditioning Co.s are out of control with their pricing and then you may get a rookie whose primary purpose to be at your house is to collect as much as he can wether he fixes your problem or not) I believe a good Handyman, if he knows a liitle bit about circuitry and has good common sense could easily do this. I will finish of here. You may be transferred to the HVAC dept. Good luck.

akjoha,

It sounds a bit like the bearings may be gone on the fan motor.
This is the most common cause of a humming fan motor.
It could be the capacitor but they commonly outlast the motor.

I can understand your reluctance to call a service person back but it may be a difficult repair for you to do.

If you want to check the motor bearings you would turn the power off to the furnace and remove the blower compartment door.
It will either be a belted fan or direct drive.

Either way get a hold of the end of the motor shaft see if there is any side to side play.
A bit of end to end movement is ok but any detectable sideways movement can cause it to not start.