Rheem 90RJ12EHS01 will not ignite.

[hoogerhs]

Hello, my name is Steve, I'm new to these forums. Like many I'm here in search of some help. It's getting colder so I decided to test out the heat before it gets too cold. Luckily (or not) I found that my unit is not starting up properly. The Unit is a Rheem WeatherKing 90RJ12EHS01.

So here's what I'm seeing after pressing the safety switch on the -
1> The inducer fan starts up.
2> A moment later I hear a click then the ignitor begins to glow.
3> This glows for a moment then a second click is heard. Is this the gas valve trying to open?
4> Shortly after the ignitor turns off and the inducer fan turns off.
5> A few seconds later, the process starts over.
6> After two or three times though these steps, the furnace will start the main blower and then shut down after 3 to 5 minutes. It'll then stay off for a while before starting over from step one.

I never hear any gas flowing (or smell it). The gas valve is in the normal operating position. I've replaced the ignitor with a brand new one, I see the same failed startup sequence.

Any suggestions on what to try next?

I've taken a video of the sequence I've tried to describe, if it is helpful I will post it somewhere for reference.

Thanks,
Steve

[Freon]

2> A moment later I hear a click then the ignitor begins to glow.

Since the ignitor is new I will assume it's hot enough to ignite the gas.

3> This glows for a moment then a second click is heard. Is this the gas valve trying to open?

This sound could very well be the gas valve opening. Next time you try and start the furnace, put your hand on the gas valve and you should feel the vibration of it opening when you hear that sound.

4> Shortly after the ignitor turns off and the inducer fan turns off.

Since there is no flame, the flame sensor is shutting down the system. Check the burners to be sure they're clean and nothing is interfering with the gas flow. Make sure you have gas at the furnace. Any work done on the house since last winter?

If the noise you hear is the gas valve, then it appears the solenoid is operating. If you're willing to try, CAREFULLY jumper the gas valve using the 24 volts from the R terminal and the C terminal on the control board. Be very careful so you don't break the control board. Turn off power, install jumpers, then turn on power and listen for the flow of gas. If you hear gas flowing you need to check for any debris and check that the HSI is correctly installed.