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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 19554
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a Ruud Achiever 90 plus that won't light. When it

Customer Question

I have a Ruud Achiever 90 plus that won't light. When it calls for heat it clicks repeatedly like it's trying to light, but nothing happens. It does this twice before blowing cold air for a couple minutes and trying again. I watched the lights after and the Ok light was blinking once.
Any help you can give would be greatly appreciated.
Thanks so much,
Chris
Submitted: 1 year ago.
Category: HVAC
Expert:  Rick replied 1 year ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.
How old is your unit? Does the igniter glow? how many times does the LED blink before it pauses and repeats?

Customer: replied 1 year ago.
Hi Rick,Thanks for getting back to me. Not 100% certain on the age, but it says it was converted back in 2003, so it's at least 12 years old. If you mean the electric spark when you're referring to the igniter glowing when it starts up, I do see that. As for blinking, it only blinks one time before pausing. My understanding is that's just the one hour lock out, so I don't really have any code to troubleshoot off of.
Expert:  Rick replied 1 year ago.

Ok, that's odd because the specs for even the earliest version of this furnace (19 years old) show a hot surface igniter not spark ignition. You need to check for 24 vac at the gas valve while it's arcing. If you have 24 v then the gas valve is suspect. If you don't then you either have a bad board or the connection between the board and the gs valve is faulty.

Customer: replied 1 year ago.
Ok I remember reading that on the troubleshooting tree, but I'm pretty new to it. Do you know I would check for 24 vac?
Expert:  Rick replied 1 year ago.

You probe the 2 leads on the valve with a voltmeter

Customer: replied 1 year ago.
Hi Rick,Sorry I haven't gotten back to you sooner, it was a busy weekend. So I've been trying to follow the diagram and figure out where the 2 leads are to connect to and test for 24 VAC. I'm not having any luck. I've attached some pictures to see if that helps any.Thanks,Chris
Expert:  Rick replied 1 year ago.

Last picture. gas valve is yellow with a brown dial on top. Probe those 2 leads connected to the gas valve while the electrode is arcing. You need to put the panel back on the blower compartment or nothing will work. The blower door switch will kill the power if it's not pushed in. Also put the cover back on the control board.

Customer: replied 1 year ago.
I see two green wires, a yellow wire, and a blue wire. I'm guessing I should probe the two greens?
Customer: replied 1 year ago.
Hi Rick,Just following up. I see there are two green wires, one that is green and one that is green with a yellow stripe. Are those the two that I probe, or should I be probing the yellow and blue?Thanks,Chris
Expert:  Rick replied 1 year ago.

The greens are ground. My wiring diagram shows blue and yellow as the live leads

Customer: replied 1 year ago.
Ok thanks. I tested the blue and yellow and the reading was jumping around anywhere from 20 to 35 as it was sparking and trying to ignite.
Expert:  Rick replied 1 year ago.

Ok, the variation could be due to a bad connection or probe contact but the voltage you read should b adequate to open the gas valve. So since you have voltage to the valve while the electrode is arcing but no gas to the burners/no ignition you probably have a faulty gas valve