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check exchanger for sure

Originally Posted by Glennhvac

As far as the board I have seen plenty of boards fry when a motor goes bad especially those amp sucking 3/4 hp units. To me it's a wonder those micro contacts in those board relays don't die faster than they do considering the load they are switching.

Amen on that Glenn.



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Those rollout switches do not always have to have flame rollout to trip. It can get plenty hot in that area while the thing is cycling on limit. Curious if that switch was tripped when you first went on the no heat call. As far as the board I have seen plenty of boards fry when a motor goes bad especially those amp sucking 3/4 hp units. To me it's a wonder those micro contacts in those board relays don't die faster than they do considering the load they are switching.

Originally Posted by dex1

Going back soon. With the blower motor not working and burners cycling for at least 12 hrs could it have burned a hole in the HX and it starting showing up after blower was changed?

Dex1

+1 this was my message all along, but few seemed to listen.

Originally Posted by MAC AIR

is the new blower motor right rotation?

The orig call was no heat and had a bad blower motor replaced the motor and the board died replaced both and furnace ran great for several cycles and left. 24 hrs later tripped on roll out, reset and ran great. 24 hrs latter again it happend. Going back soon. With the blower motor not working and burners cycling for at least 12 hrs
could it have burned a hole in the HX and it starting showing up after blower was changed?

Dex1

is the new blower motor right rotation?

Where is the furnace getting it's combustion air from? Is it located in a closet?

Sure. But not likely this "Grand Canyon" crack appeared at the same time the blower was replace. With no symptom of the crack before.

could be the secondary hx is plugging up I had a carrier do the same thing would work ok for a couple of days and intermittently trip the rollout switch, while you had the blower out did you check the secondary hx?? I have had a lot of the secondary hx plugged with dirt and pet hair. Is it the same rollout switch tripping?? Can you try swapping it with one of the other rollout switches assuming it has more than one, to see if it is a bad switch??

Originally Posted by Frederick_Tech

If its the roll out and not the limit I would not think it has anything to do with the blower and board replacement. .

So if you have a grand canyon size crack in the HX the blower will not effect the roll-out?

If its the roll out and not the limit I would not think it has anything to do with the blower and board replacement. I would be looking at the HX and venting.

Originally Posted by dex1

kind of weird worked ok until I had to replace fan and board. Any thoughts

Not weird at all, if the blower was out, this is probably why the flame never rolled out. I would no doubt be looking at the HX really good. Why did you change the fan and board if it worked ok?

Delta T? Dirty air filters? Collapsed duct work? Dirty Evap coil?

I'm thinking airflow since the problem occurred after you changed blower motor and control board.

How did you set your fan speed?

Have you tested the RO switch to see the point that it opens? Those things are made in china.

good point maybe when the HX gets hot it open up.

Replaced the blower motor on start up the board died.

could it be a crack in the heat exchanger that's only opening up after the furnace runs for awhile?

are you sure it's a roll out and not a limit? if so, check the hx. i find it odd you changed the board and blower motor at the same time. was it flooded or something?

Amana roll out switch

Hi All,
I replaced a blower motor and a WR control board on a Amana GUCA 13 year old furnace worked 1 day then no heat fan run all the time. Tripped out on roll out reset and furnace runs great for 5 starts and no sign of any rollout. Next day no heat same thing no signs of roll out with and without cover on. kind of weired worked ok until I had to replace fan and board. Any thoughts