mobilehomerepair.com

Hello.

Nordyne M1MB 09A AW

Just recently I noticed two things:

1) The transformer is buzzing, even when the unit isn't running, so I'll replace that.

2) Just before it fires up and the blower comes on, I'll get anywhere from 1 to about 6 loud clicks. It's not the relays on the circuit board, as I used a paper towel tube up to the circuit board and it's not coming from there. Besides, the clicking sounds are much louder and much "stronger" than a relay sound.

Anyone know what that clicking is, and should I be concerned about it? Or perhaps the transformer is weak, and it's not giving enough power to whatever "switch" keeps trying to engage?

Thanks.

I'll look into more, but I'm thinking it's the ignitor.

Does the ignitor make a loud click when it engages?

I'll just continue talking to myself here. lol

Looking into the combustion chamber, the ignitor glows red hot, the gas valve opens, the gas ignites, then goes out. This is accompanied by the loud clicking, and that cycle happens about 4 to 6 times before the gas stays lit and the furnace runs fine.

So now I'm thinking it's the gas valve or flame sensor.

Anyone?

On the M1 the igniter is the flame sensor. Not real sure about all the clicking but there is a fair amount as the unit cycles up. Check for a spider web in the main burner oriface before replacing any parts. That will cause a small flame and the igniter will not prove flame thusly shutting the gas valve down.

Thanks for the reply Dale.

I did find out that it is indeed a combination sensor and ignitor.

There is no problem with gas pressure or flame strength. So unless there is some weird electrical issue, the problem seems to be the sensor that sometimes fails the flame, thus closes the gas valve. The ignition module then opens the gas valve again, the gas ignites, but the sensor fails it again and shuts off the gas valve. This cycle repeats 3 or 4 times before the sensor passes the flame, and then the furnace runs fine. I've also checked, and yes, the gas valve has got 24VAC.

The furnace is 6 years old and under heavy use, so I've ordered the 3 main parts that will most likely fail. That is, the transformer (currently buzzing very loudly), the circuit board (I've had to replace it once before), and the sensor/ignitor combo. I don't want to be stuck in the middle of winter with a huge service call and local parts that literally cost 4 to 5 times more than what I can get online.

Now I'm by no means an expert, but does that make sense?

Makes perfect sense to have those on hand. I would replace the igniter in your case. Probably glazing over and not reading well enough to prove flame. Some guys claim you can lightly scuff them with steel wool but since I have a business I prefer not to have a customer go down during the night or weekends. Call backs are not good for business.

Thanks Dale.

I'll let you know how it works out.

Did you get this figured out?

Our furnace was double cycling intermidantly a couple years ago and after many hours of trying to catch it when it happened and get over there to trouble shoot it I ended up cleaning the flame sensor with some steel wool and it has worked good since. I found out furnaces are not my strong points in trouble shooting!