Rheem Criterion II won't ignite

roundstones · 10-26-2012, 11:52 PM

I have a Rheem Criterion II that will not ignite the gas. Blower comes on, cycles through, and releases gas but the igniter never glows. I put a meter on the line for the HSI and the voltage climbs to 9VAC but never exceeds that amount. Pulled the HSI and gave it 120VAC from the wall. It glowed red hot. Checked the voltage at the pressure switch and it climbs to 24VAC for a short while and then drops to zero. Disconnecting the connector to the pressure switch and checking the voltage at the connector it remains at a steady 24VAC. I can manually light the furnace and it will run normally. Does anyone have any ideas here? How do I know if its the board? Is there another test for the pressure switch? Any help would be greatly appreciated.

how · 10-27-2012, 02:17 AM

I think that unit is supposed to have a diagnostic led.

(1) BLINK FOLLOWED BY A 2 SEC. PAUSE 1 HOUR LOCKOUT
(2) BLINKS FOLLOWED BY A 2 SEC. PAUSE PRESSURE SWITCH IS OPEN
(3) BLINKS FOLLOWED BY A 2 SEC. PAUSE LIMIT SWITCH IS OPEN
(4) BLINKS FOLLOWED BY A 2 SEC. PAUSE PRESSURE SWITCH CLOSED
A FIFTH CODE IS ADDED ON DELUXE MODELS THAT HAVE TWINNING CAPABILITIES
(5) BLINKS FOLLOWED BY A 2 SEC. PAUSE - FAULT.

roundstones · 10-27-2012, 11:31 AM

Thank you. I'll check for the LEDs.

Houston204 · 10-27-2012, 04:26 PM

If you are getting gas and the hsi works with your test, you need a new board.

roundstones · 10-28-2012, 10:43 PM

The board is the only possibility at this point?

roundstones · 10-29-2012, 06:49 PM

Okay so trying to run the furnace I get a 1 hour lockout error code. Checking the resistance at the gas solenoid, I get 280 ohms resistance. I don't have a schematic and can't track down the relay for the HSI. Traced the wires from the HSI through a couple of connections and back to the board at a 6 pin socket. There's a little black Siemens component directly above the 6 pin socket. It looks like there might be a circuit trace from the 6 pin to the component. The other side of the 6 pin appears to go to neutral. Is this Siemens component the relay? Any ideas what I might be looking for? Thanks.

roundstones · 10-30-2012, 01:12 PM

Is there a source for the HSI relay and is it worth it to just change out the relay?

how · 10-30-2012, 04:49 PM

Have you confirmed what the board is trying to feed the HSI.
Not all HSI run on 120V.

roundstones · 10-31-2012, 01:17 AM

I have not gotten more than 9VAC at the HSI from the board. It (the HSI) tests out at about 200ohms of resistance. That would make the current .045 amps or 45 mA. Does this seems like it could light up an HSI? I don't know much about these but I thought this one was supposed to get 120VAC. What do you think? I was able to get it to glow when I applied 120VAC during a bench test with the HSI pulled from the furnace and given a dedicated line from the wall.

how · 10-31-2012, 01:36 AM

Sorry but folks measure things here in so many different ways.

Unplug the HSI, and measure what the board is supplying in VAC with a call for heat?

roundstones · 10-31-2012, 02:22 AM

I did. That's when I got the 9VAC measurement from the board. I disconnected the HSI and plugged the multimeter directly into the connector coming from the board. The resistance measurement on the HSI was done when it was isolated and not on the circuit.

how · 10-31-2012, 02:42 AM

Thanks for the clarification.
Insufficient voltage to the HSI with codes saying its not a safety limit or PS fault, all point to a board problem.
With board problems, always check that all your ground lines are good but beyond that I'd be replacing the board.