central air blower wont turn off - help

[timaishu]

We ran our heater last night because it was very cold in the house. First time we have used the heater in years. Havnt used the unit itself in over a year. Well when it was time for bed, I turned the thermostat to off, but the darn thing wont go off. The furnace turned off but the blower fan is still going.

It has been running all night and now the fan is making a really obnoxious squeaking sound every few minutes and it it driving me insane.

I went outside to the breaker box and flipped the one label AC but it did do it. It must be on the main switch.. Is it okay to straight up unplug the furnace? I can access its wall outlet plug.

 

[Flash Gordon]

We ran our heater last night because it was very cold in the house. First time we have used the heater in years. Havnt used the unit itself in over a year. Well when it was time for bed, I turned the thermostat to off, but the darn thing wont go off. The furnace turned off but the blower fan is still going.

It has been running all night and now the fan is making a really obnoxious squeaking sound every few minutes and it it driving me insane.

I went outside to the breaker box and flipped the one label AC but it did do it. It must be on the main switch.. Is it okay to straight up unplug the furnace? I can access its wall outlet plug.

I don't see any reason why you shouldn't. It might even reset itself if you try plugging it back in after 30 minutes or so

 

[cartman57]

Some tstats have a 'fan on' option, make sure it not that first then turn off the main breaker for the furnace, or a switch on the unit somewhere.
Remove the cover where the blower motor is, it probably is a direct drive (no v-belt) the bronze bushings are dry or worn out, easy fix is to spray some thin oil in the end of both sides. Some motors have a drip capilary tube for this reason.

 

[timaishu]

The fan is set to auto right now. It either "on" or "auto". The thermostat is set to the off position right now. Im going to try the main breaker in a bit as I assume that will get it. I dont just want to reset all my clocks. lol

 

[timaishu]

The fan is set to auto right now. It either "on" or "auto". The thermostat is set to the off position right now. Im going to try the main breaker in a bit as I assume that will get it. I dont just want to reset all my clocks. lol

Update: Turning it off at the breaker box didnt reset it. Gonna have my neighbor take a look when he has a chance, I believe he does or did HVAC work in the past.

 

[cartman57]

Internal fan relay contacts might be 'welded' closed, hopefully it won't cost you too much $, good luck.

 

[1oldsalt]

It's no problem to unplug the FAU (Furnace).
Sounds like you need what is called a Fan and limit control switch. They are between 50 and 70 bucks.
I'm going through the same thing with my mothers heater but it's a little difficult finding parts for a 40 year old unit.
The squeaking sounds like you may need a new blower motor as well.
If you are handy and want to do it yourself, Johnstone supply carries whatever parts you need.

 

[jpegs13]

The tstat is bad. Just replace it.

 

[Setec Astronomy]

Internal fan relay contacts might be 'welded' closed, hopefully it won't cost you too much $, good luck.

Timaishu, this sounds like good internet troubleshooting. Unfortunately, there is usually a reason the contacts weld, and one of them is the fan motor is no good (and as mentioned, the squeaking is a good indicator of that). Also these days that relay is sometimes on the main board for the unit (ask me how I know), which can be big bucks. I've also seen inducer motors that fail somehow into this "on all the time" mode.

What make of air handler is it and how old? I have found that motors aren't what they used to be. My Carrier is 12 years old and I've had to replace the blower fan multiple times, including the time it blew the control board.

EDIT:

The tstat is bad. Just replace it.

Now that you mention it, I've had that as well, where the fan relay in the thermostat welded.

 

[cartman57]

Timaishu, this sounds like good internet troubleshooting. Unfortunately, there is usually a reason the contacts weld, and one of them is the fan motor is no good (and as mentioned, the squeaking is a good indicator of that). Also these days that relay is sometimes on the main board for the unit (ask me how I know), which can be big bucks. I've also seen inducer motors that fail somehow into this "on all the time" mode.

What make of air handler is it and how old? I have found that motors aren't what they used to be. My Carrier is 12 years old and I've had to replace the blower fan multiple times, including the time it blew the control board.

EDIT:



Now that you mention it, I've had that as well, where the fan relay in the thermostat welded.

Yup, too many things to try and troubleshoot without knowing what brand, age, etc.
Good forum is HVAC-Talk: Heating, Air & Refrigeration Discussion use it all the time for work.