BGU07516A FOUR FLASHING LIGHTS

[stew5978]

Issues with furnace running short cycles, blower runs constantly through entire process.

Process

Solid green light
Burners ignite
Runs for approx 3 mins.
Burners shut off
Four flashing green lights (limit switch)
Blower continues for approx one min.
Green light returns solid
Burners ignite
Runs for approx 3 mins
Repeats process

So, as far I can tell something it tripping the limit switch. I assume the switch is good because it resets and allows to run again. I believe it automatically resets but I can't be sure that is what its doing since I am not experienced at this. I also cannot locate where the switch is to manually reset, nor do I know what it looks like. I vacuumed and blew out entire furnace unit, replaced filter. It is still running and heating, just not like it should.

Any thoughts on what else I should clean or check before calling tech?

thanks
stew

[furnaceman]

Vacuuming it out and changing the filter is a good start. Don't take this wrong, but how long was it prior to this change did u last change filter, if it was quite awhile, or its been awhile since a tune up was done, the blower wheel could be dirty.
usually when a unit goes off on limit, its because its to hot in the furnace. This could be the result of filter neglect, dirty blower wheel, the fan motor could be going bad or its cap could be going out. There are a few other reasons , but they require some technical skill to test for.
Now its possible the linit is getting weak.

If u have changed the filter, cleaned out the unit, made sure air is flowing normally out of all the ducts, i would suggest calling a tech so he/she can ck for the other causes. It is possible that u have a bad limit, and u could order on from this site, however, its better not to part change to try and fix a problem, if it turns out it is the problem, the price for it here is very reasonable, and they have a great customer service

[Robert]

IF you have a/c split system, be sure a-coil is clean as well. Great airflow at the supply registers will give insight on airflow problem.


Does furnace seem overly hot when it kicks off ?


Thanks,
Robert