Intertherm MGHA 056ABFC-01 Blower Problem

[kart18]

This is a natural gas furnace. The fan is cycling on and off. The furnace comes on and shortly there after the fan comes on and runs for about 30 seconds and then shuts off for about 10 seconds and then back on for 30.........I replaced the fan switch and it is still not working right. It is still cycling. 30 seconds at first and the more it cycles the longer the fan will stay on before it shuts off. I think it actually got up to 2 minutes last night. I don't know what to check or replace next. The furnace is 16 years old. I don't remember ever replacing the high limit switch. Could this be the problem? Does the high limit switch have anything to do with the fan cycle?

Thanks, Todd

[Robert]

Hi Todd,

If you have a/c, make sure a-coil is clean and filter is clean.

With both clean and new fan switch, if it still doesn't work, need to see if something inside chamber has come loose and allowing air to blow across fan switch cooling it down quickly causing it to cycle.



Thanks,
Robert

[kart18]

Good Morning Robert,

Thanks for the reply. I don't have air conditioning through my furnace. Filters are new. Even when they are not new I clean them once a month. So, I will check tonight and see if there is in fact anything 'loose' inside the chamber. I am however thinking I may have gotten a bad 'new' fan switch. I know this is slim in none, but it does and can happen. I have someone coming on Saturday to check the voltages and do some test. I'll get it sooner or later. I also checked the temp rise last night. It was 70 degrees going into the furnace and after about 4 or 5 cycles it was 135 coming out of the closest register. Well with in range of the 70 degree rise listed on my furnace. Thanks again and I will let you know what I find.

Todd

[Robert]

Hi Todd,

Sounds good and yes it does sometimes happen.



Call Nordyne and ask them if there are any shields inside furnace that may have come loose allowing air to blow across switch cooling it down and opening it.



Thanks,
Robert

[kart18]

Hello Robert,

Well, I thought I found the problem with my fan and extremely high gas bill. I'll explain - I took the fan out on Sunday morning and looked down into the fire box area. There is a shield over the high limit switch but not over the fan switch. I couldn't really tell if there was one there or not so I decided to look down through the furnace and see if I could find a shield that had fallen off. When I took the damper out to look down into the cross over tube I found that the tube had in fact actually fallen off the vent tube and was lying under my home on the ground. Hence the high gas bill and the fan cycling problem, so I thought. I hooked the cross over back up and it seemed to fix the fan problem and I actually got a ton of heat into the house now that I was done heating the outside. OK, here's the thing, my fan is still cycling to much. Robert, do you have the number for Nordyne or know where I can find it? I need to find out if there is supposed to be a shield over that fan switch and how exactly the furnace should run when it is running right.

Thank you in advance for all your help, Todd

[Robert]

Hi Todd,


They should be side by side and if so, is the fan switch on the right or left ?



Thanks,
Robert

[kart18]

Hello Robert,

They are in fact side by side and the fan switch is on the right hand side.

Thanks, Todd

[Robert]

Hi Todd,

The shield over the limit may be wrong or may not be. Go here to find closest Nordyne dealer to you and call them and see what they say.

http://www.intertherm.net/IMHDL.htm


They may require that they come out, but that is best way to find out for sure.


There has been some problems like this, not sure it is the case here, but may be.


Would need to confirm through Nordyne or be able to test temps and fan switch to see if it is cooling down to soon.


Thanks,
Robert