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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 19520
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a RUUD Achiever 90 Plus furnace that goes through

Customer Question

Customer: I have a RUUD Achiever 90 Plus furnace that goes through start up but does not get gas to ignite.
JA: Thanks. Can you give me any more details about your issue?
Customer: I'll try. ASk questions and I can answer them
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Submitted: 11 months ago.
Category: HVAC
Customer: replied 11 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Rick replied 11 months ago.

There is an additional charge for a phone call and I first need more info about your situation. If you still feel the need to talk you can request a call later but first I need the actual model number of your unit (it's on the rating tag inside the burner compartment).

Customer: replied 11 months ago.
Remove the phone call request and put me in que for web help
Expert:  Rick replied 11 months ago.

You're already there. I need your model number so I can help with your issue

Customer: replied 11 months ago.
Rid achiever 90 plus down flow ugta-09ezajs
Customer: replied 11 months ago.
RUUD
Expert:  Rick replied 11 months ago.

How old is this unit? It's be around for almost 20 years with a number of variations along the way. If you don;t know give me the serial number I can probably figure its age from that

Customer: replied 11 months ago.
Mfg 2004, installed 2008
Expert:  Rick replied 11 months ago.

What sequence is the LED on the control board (in the blower compartment)? Do you have spark ignition or HSI (hot surface ignition, a "glow plug")?

Customer: replied 11 months ago.
2 green lights on, yellow light off.
Spark ignighter
Expert:  Rick replied 11 months ago.

Nothing is flashing? No flash indicates normal operation. If the thermostat is calling for heat, turn the power off to the furnace wait a minute then turn it back on. Tell me what happens

Customer: replied 11 months ago.
Reset power. Set thermostat to 4 deg higher than temp. 3 green lights solid. Fan comes on for 15 sec then a click and the ignition system begins clicking for 10 sec and unit shuts down and restarts the sequence to fire the burner--fails and unit turns on larger (purge?) fan and then shuts off
Expert:  Rick replied 11 months ago.

If the igniter is arcing you need to check for 24 volts at the gas valve. Do you have a multi-meter?

Customer: replied 11 months ago.
Aor
Expert:  Rick replied 11 months ago.

I don't understand your last post

Customer: replied 11 months ago.
have multimeter in hand
Expert:  Rick replied 11 months ago.

You need to test for 24 volts AC across the 2 leads on the gas valve while the igniter is arcing. If you have nothing there trace the leads back to the board and test there. You'll have to rig the blower door/panel switch closed so you have power to the unit if you have to test at the board

Customer: replied 11 months ago.
I have 24v at gas valve when arcing
Expert:  Rick replied 11 months ago.

Then the gas valve should open and the burners should ignite. This is an indication of a problem with the gas valve

Expert:  Rick replied 11 months ago.

If gas supply pressure is adequate and the burners are clean then you probably need a new gas valve. We would test manifold pressure to rule the above in or out

Customer: replied 11 months ago.
I think I tested the valve correcyl
Expert:  Rick replied 11 months ago.

Ok, the above still applies. I'd be more concerned about no voltage due to a testing error than a positive voltage reading.

Customer: replied 11 months ago.
Voltage went from 0 to positive voltage when arcing
Expert:  Rick replied 11 months ago.

I can't confirm your testing technique from here. All I can tell you is what needs to be tested. If you have 24 volts at the valve then it should open and the burners should fire up. If you don't have 24 volts then you could have a bad connection between the board and the valve or a bad board.

Customer: replied 11 months ago.
Now the green power light is solid and the OK light is slowly flashing
Expert:  Rick replied 11 months ago.

What's the flash sequence? how many times does it flash before it repeats?

Customer: replied 11 months ago.
Slow, steady flashing. No sequence
Expert:  Rick replied 11 months ago.

That's not indicating an error

Expert:  Rick replied 11 months ago.

Normal operation after an ignition failure is to try to 4 times then lock out for an hour and flash once followed by a 2 second pause

Customer: replied 11 months ago.
Back to the gas valve test: I have 2 green leads, one goes to the fan motor and the other to the door switch. Yellow and blue wires also on back side. Do I test the yellow and blue wires?
Expert:  Rick replied 11 months ago.

Green is the ground. You need to probe yellow and blue.

Customer: replied 11 months ago.
Ok that's what I did. They lead to a connection on the fan housing next to the board. They still show voltage when arcing.
What about the three limit switches or the diaphragm?
Expert:  Rick replied 11 months ago.

If you have voltage to the valve that's the only thing that's relevant. If there was a problem with the other devices you wouldn't have voltage to the valve.

Customer: replied 11 months ago.
Ok. I guess I'll call a tech.
Expert:  Rick replied 11 months ago.

I'd appreciate a favorable rating