Hey guys, I have an old Singer CB2105 gas furnace and it just stopped working a few days ago. The blower motor will not turn on even if I set it to on. I haven't seen any fuses anywhere and the breaker is fine. The burner does not ignite either (the gas does not start coming out, no clicking noises) and the pilot is lit.

A few days ago I noticed that the blower motor stopped working and the burner would ignite so no heat would come on. I don't know how long it was like that before it, but soon as I saw that I turned off the heat.

The fan limit control switch (ehh is that the right name for it? lol) looks like it may have been melted a little bit maybe from the blower not going on, or it may have been like that all along. Could that cause the burner to not ignite and prevent the blower from turning on even if you switch it from auto to on? Any help would be greatly appreciated. I also can't find the capacitor, do all furnaces have them?

 

singer? You may not want to invest any amount of time or money in that old of a furnace. Singer has not made furnaces for many, many years!!! However, there may be a limit that is tripped which has opened up the main circuit in the furnace. Good luck......

 

If you are turning on the blower via the thermostat & it does not come on, you could have a low voltage problem. Make sure the breaker & any emergency or service switches are turned on. Also verify the furnace blower door is on & secure. Once all of that is verified, remove the thermostat & check for 24 volts AC between the R & W terminals. Report your findings here.

 

The breaker is on for the furnace, I don't see any emergency or service switches anywhere (blower motor says something about overload automatic reset, no button anywhere on it). It's been a while since I've used a voltmeter but across R & W with the meter set to 20v AC it reads 0. With just one lead on R it was reading .24v and pretty much the same for everything else, fluctuating between .23/.24. That's not 24 volts correct? I would assume it would read .24 or .024 for 24v if it were set to 200v but it was set to 20ac..

Does the limit switch need to be manually reset if its tripped? I'm sure it went off when the burner was on but the blower wasn't working. Any help would be great, my mom is freezing lol

 

Some limits are manual reset, some are not. I don't know if the limit on that furnace is line or low voltage but the blower should run in either case. I suspect more than one problem but without a wiring diagram trying to tell you how to fix it is going to be next to impossible. If you have a wiring diagram, please take a good clear picture of it & post the picture either here or on a photo hosting site such as photobucket.com then provide a link here.

 

You want to measure the voltage between chassis ground and R, and between chassis ground and W for example.

Set your voltmeter to the next highest setting above 24 volts and set it to measure AC voltage.

When the thermostat is calling for heat you should have 24 VAC at both R and W.

 

Hey I checked the voltage at R & W and both read 0v. The thermostat is calling for heat set well above +5 deg (its like 44 in here, set to 70 lol). So judging by that it seems that some type of safety switch triggered? I took several pictures of what I'm working with. This furnace does not look nearly as advanced as pictures I have seen from other sources online. I checked many times and still do not see a switch. Maybe someone could recognize some of the parts, maybe a hidden switch? lol


Picture of the limit: ImageShack® - Online Photo and Video Hosting -- I believe there was a problem with this a while ago, I think my dad just rebuilt it instead of replacing it with a new one. I'm not sure if he couldn't find a replacement or if it was just cheaper to do so. As you can tell it looks semi melted.

Picture of inside the control panel: ImageShack® - Online Photo and Video Hosting -- From what I can tell, the gold part on the left is the transformer and the black part on the right is a relay? I've followed all of the wires inside the furnace and the hot/neutral coming in is only wired to a wall mounted switch that goes to the breaker. I haven't seen a capacitor anywhere. Do all models have one?

Picture of the blower motor: ImageShack® - Online Photo and Video Hosting

Picture of the solenoid? ImageShack® - Online Photo and Video Hosting -- I think that is the solenoid correct? Where the pilot/thermocouple connect to.

Picture of the burners/solenoid: ImageShack® - Online Photo and Video Hosting


That is pretty much all that is inside the furnace, besides the burners/vents. Any ideas? =X

 

No sign of any 24 VAC to operate the furnace based on your last post.

You should check to verify that you have the power switch to the furnace turned on. Open the switch box and verify you have 120VAC to the furnace. There should be a junction box in the furnace ---- check to verify you have 120 VAC at that point as well.

Then verify that you have 120 VAC at the input side to the low voltage transformer and 24 VAC on the transformer secondary.

 

Alright sorry for taking so long to get back to you I've been gettin up for work at 4am everyday and ive been beat by the end of the day.

I have 120vac at the switch, 120vac entering the control panel. On the transformer I see the hot and neutral coming into the transformer. On the other side there are two wires coming out, one would have 16vac and one should have 8vac, combined for 24vac. I put one lead on the 16vac end with the other lead on the neutral coming into the transformer and I got about 5vac, same with the 8vac + neutral about 5vac. I tried using one probe on the 16vac and one on the 8vac and came up with 0vac (dont know why i did but hey, lol)

Judging from this I have low voltage output from the transformer and should replace it correct?

 

Something sounds odd with your description of the transformer output.


If you measure the output across the two secondary wires, you should have about 24 VAC.

It's not clear to me how you are getting other voltages, but it doesn't sound right.


Usually if a transformer goes bad, it's burned out and you will get an open circuit across the primary or secondary wires if you check it with an ohm meter.

It sounds like you need to check out the transformer in more detail to verify that is your problem.

Also, typically one side of the transformer secondary is connected to chassis ground.

 

basically, on the transformer i'm looking at, there is a wire coming off the neutral that is hooked up to the back of the transformer, and a wire coming off the hot 120vac to the back of the transformer. on the front there is a 16vac output and an 8vac output then if combined they are 24vac.

To test it, I put one lead on the 16vac output and the other on the neutral that is coming into the control box where the transformer is at (Same neutral that is going into the transformer). I did the same for the 8vac output and both read about 5vac

 

"If you measure the output across the two secondary wires, you should have about 24 VAC. "

If you mean putting one lead on the 16vac output and the other on the 8vac output, then I do get 0vac

Also, does it matter if the thermostat is set to call for heat or not? I've been doing it with the thermostat set to off.

 

no, your output should have a hot leg 24V and a neutral leg - Common. not 16 and 8. There is no such thing, because remember we are working with alternating current, not direct current

 

Someone may have put a multipurpose transformer in here (one that you use for doorbells n such). Might explain why I have a 16vac output and an 8vac

 

that might, however, 16v is not enough to run most controls...............

 

If the 16vac and 8vac output were connected though, that would give us a 24vac output

 

no, not really, it doesn't work that way, get the proper transformer.