Check out some similar questions!

Mtumeo2000 · Feb 18, 2010, 07:06 PM

Neighbor called me this night his house is cold and it 34 degree outside and they have a 6 week old. Rheem Criterion furnace RGLJ-7 cannot rember the rest of it. The control board green light blinking 3 times and blower motor runs all the time. I read that it a limit switch is open which I found none open with my fluke by an ohms test. Of course I have try turning off the furnace by the circuit breaker wait 1 minute then back on. The only way I can get it to work. That I remove the wire to one of the limit switches and break the circuit and then put it back on I will get the unit to run ONE time. I have check out everything that can think of and the only thing I can come up with is the control board. They are dirt poor right now and I do not want to make a 200 dollar mistake. I do work on commercial Air handler and Refrigerators so I do know a little (very little) about this.

hvac1000 · Feb 18, 2010, 07:54 PM

Clean the flame sensor. Might look like the ones below or different. Use fine sand paper or steel wool.

Mtumeo2000 · Feb 18, 2010, 08:07 PM

Already did that too. Also I check voltage to glowplug it good tooand I have check the pressure switch which is good. The induce fan run all the time with the blower it seem the gas valve does not open unless I do as I stated above. After reading a few post on here the amber light does not stay on it flicker at start up then stay off and I do not see the second green light. Now it will stay on when as I stated above is done.

Mtumeo2000 · Feb 18, 2010, 08:08 PM

Thanks hvac1000

Mtumeo2000 · Feb 18, 2010, 08:35 PM

I might have come up with an answer to my problem I live in Ohio and this did not start until the second snow fall that we had which gave us 24 inchs of snow. They live is a old ranch style house could the snow preventing the draft of the gases from the flu pipe causing my firebox high limit to kick out. Is the firebox limit switch for this unit is a fuseable link or a resetable one. As I watch the pain in the butt unit go through it ONE cycle the flame was blue and did not row out.

Mtumeo2000 · Feb 22, 2010, 06:26 AM

To let all you guys know it was not the flu pipe problem it did turn out to be the circuit board problem. When I put the new one in the furance work like nothing was wrong at all and when I got the old one out it a well lighted area I notice that the chip on the board had a big bubble on it were it got hot for some strange reason.
Took temp with the down draft furance running in the blower area it was the room temp 72 the firebox, it was 160 (took it at the high limit area) then downstream at the first vent 120, it has run all weekend with no problems want to thanks all who help me on here.