I see this was a question from yesterday too. Some help would be much appreciated. I have a rheem rgph 07EAMGR. The blower comes on, them the ingnitor lights, then the gas (natural gas) burners start up. A few seconds later the whole thing shuts off. After a few minutes the whole cycle begins again.
I called out a repair guy who came out on friday, looked at it for a few minutes, announced that I need a new circuit board that he would order and get back to me on monday. now it is thursday and still no repair guy.
I read a few other posts and saw a suggestion to clean the flame sensor. So I removed the screw that held it in place but couldn't pull it out. I tried to wipe it off with out removing it but I'm not sure how thorough the cleaning is supposed to be. some guidance would be great.
Thanks

 

I had a short cycling problem last winter and learned a few things that may be causing it. I'll post them here, because the repair guy should have checked them before declaring a dead circuit board.

~ dirty filters
~ clogged / blocked return air ducts (some systems have filters on these, too, so that may bear some looking into)
~ dirty A/C plenum (very often the A/C system shares part of the furnace; if this is clogged or blocked then it will cause short cycling too)
~ defective flame sensor
~ defective temperature sensor
~ blocked vent (through the roof to the outside)
~ dirty squirrel cage blower

Cleaning the squirrel cage blower was the answer to my problem: the fins had accumulated enough dust that they were no longer aerodynamically correct, and couldn't move air properly.

All these are DIY fixes but will require some research on your part to find out how to investigate them, and then acquire replacement parts as necessary- I'm not an HVAC pro or else I'd be able to give more guidance. It took me a few days and a lot of help from a helpful patient friendly DIYer on this board.

Please make sure the repair guy has checked for all these things: the circuit boards are $100 to $200 if you buy them online and install them yourself- I suspect it will be more if the repair guy does it.

Good luck with it!
Dave O

 

It sounds like your flame sensor. We just change them out because they are cheap and we don't want a call back (and a mad customer). They can be cleaned with steel wool as a temporary fix. Also, make sure you have a good connection to the sensor. While the other items in the previous post are very important, they would generally not cause the flame to go out in a few seconds after ignition. The second possibility is a bad circuit board. If all other components check out ok, then your board is likely bad. In other words, condemning a board is usually done through the process of elimination. Board problems can be a lot more difficult to diagnose especially when the problem is intermittant. Be thankful your problem is consistant.