The furnace is a 1989 Comfortmaker GUA Series gas furnace with a White Rodgers Model 58E47-148 Hot Surface Ignition Module. With the burners unlit, the forced draft fan runs all the time. The LED light blinks constantly, which the information that came with the furnace says means "External Failure (Ignition lock-out)". It seems the cycle can be re-set by turning off the thermostat (or the furnace) and then turning it back on. It will go through the following cycle... the forced draft fan comes on immediately, there is a click, the igniter glows, the burner flames come on, there is another click, then the flames go out. It repeats this three times, then the ignitor does not come on anymore and the LED starts blinking and the draft fan stays on.

Sometimes the furnace will work fine for several days, then the house gets cold, and I can hear the draft fan blowing. I turn it off and on, and everything is fine for an hour, or maybe several days. This has been going on since late last winter. Today, it took three or four re-starts to get it going. I have had our furnace guy out three times, and he says it is working fine when he is here. Any suggestions?

The furnace is a 1989 Comfortmaker GUA Series gas furnace with a White Rodgers Model 58E47-148 Hot Surface Ignition Module. With the burners unlit, the forced draft fan runs all the time. The LED light blinks constantly, which the information that came with the furnace says means "External Failure (Ignition lock-out)". It seems the cycle can be re-set by turning off the thermostat (or the furnace) and then turning it back on. It will go through the following cycle...the forced draft fan comes on immediately, there is a click, the igniter glows, the burner flames come on, there is another click, then the flames go out. It repeats this three times, then the ignitor does not come on anymore and the LED starts blinking and the draft fan stays on.

Sometimes the furnace will work fine for several days, then the house gets cold, and I can hear the draft fan blowing. I turn it off and on, and everything is fine for an hour, or maybe several days. This has been going on since late last winter. Today, it took three or four re-starts to get it going. I have had our furnace guy out three times, and he says it is working fine when he is here. Any suggestions?


Try cleaning the flame sensor that can cause the problem you are having. It is the easiest item to do for starters. Post back with results.

So far, so good. I cleaned the sensor about 8:00 last evening and the furnace has worked since then. Thanks a bunch for the quick answer! BTW, my sensor is the straight one, not the angled one.

Jim

Also, while I had the power off to the furnace, I took off the sensor connection to the module and put it back on, just in case the contact at the connectors degraded.

Jim

Glad you got it going. The sensor pictures are just to give a general idea as to what to look for.

It is now Thursday morning, I cleaned the sensor on Monday evening and it is still working like it should. Again, thanks for the quick response! I think my issue is fixed.

Jim

No problem. I am glad you got it going.