Furnace clicks on and off (alot)

[swheele]

Hi,I'm new here and have found this to be a very informative forum and would like to see if someone can help me out.I have a intertherm model # MGHA-056ABFC-02 HEAT AND A/C unit. My problem is Thermostat kicks on,heat comes on and builds up to temp. in the unit,Fan comes on and runsbut it just runs for about a minute and cuts off ,then comes back on and runs for another minute.It does this about 8-10 times per heating cycle.(fan off and on) This can't be to efficient! I replaced the fan switch part #626337 and it still does it. Do you know anything else it could be? Any help will be greatly appreciated. Thanks Scott

[Robert]

Hi,

Take the middle black Line power wire off the middle terminal on the furnace fan-auto-on switch and also remove the blue wire from the 1 terminal.

Connect them together. You can also jumper across the 1 and middle terminals.


See if that resolves it.


Thanks,
Robert

[swheele]

That seems to have fixed it,I'll know for sure the next real cold morning we have. Thank you so much for sharing your info and knowledge on this board,money is tight and this sure helps! Hope you and your family have a great christmas. Scott

[Robert]

Hi Scott,

You're very welcome, happy to help. That switch is a common intermittent problem area. Hopefully that resolves it, if not, may be a short in wiring.

Another possibility was air getting to the fan switch cooling it down too quickly.


Merry Christmas to you and yours as well !!


Take care and best wishes,
Robert

[homebuff]

Robert!
Seems as though he's having the very same thing happening to his as I am with my Intertherm unit.
The switch you were referring to is the limit switch inside the metal power box on the burner?
I will be paying close attention to this post to see if he gets his resolved or not.

[Robert]

David,

His was just the fan going on and off, not fan and burner.

The switch is not a limit switch, it is the fan-auto-on switch at the furnace.



Thanks,
Robert

[homebuff]

Hey Robert!
Had to try the jumping the blue & black wire myself But when I did the unit fan & burner would not come on.
Took the original factory 6262920 limit switch out of the chamber & it had a large amount of dust on the 2 switches & plate.
Just got through reinstalling the limit switch Robert & it weems to be working now.
No cycling on & off & the burner does come on when turning up thermostat & then burner goes off when lowering the themostat.
Will go ahead & reconnect the Hunter digital back up the way it was before & disconnect the wires from the Intertherm thermostat & see if its still running ok.
The dust being all caked on the swtches inside the unit cause this to happen?
Thanks for your support.
David
You've been a great help.
Happy Holiday's

[Robert]

Dust can restrict the air getting to switch and change operating temps. Those two switches are a limit and a fan.



Thanks,
Robert

[homebuff]

Thanks!
It appears to be working ok now.
I'll bet the dust on the switches made a diiferance.
Had to clean it off with a rag cause the dust was kinda stickey & not dry where yo could just blow it off.
Of course the Hunter thermostat is bad anyway cause when it's hooked up the unit keeps cycling on & off like I mentioned earlier & doesn't when I have the old Intertherm standard thermostat hooked up.
Going with a standard type, don't trust those digital type unless you recommend the HoneyWell as being the best & more reliable.
Read my original post.
Left a message there.
Sorry to intrude on this one.

[Robert]

You're very welcome, happy to help.


Thanks,
Robert

[homebuff]

I'm happy now that everything is back to normal.
Your the best.
Case closed!

[Robert]