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Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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I have an Amana 90 furnace that will run but not bring the

Customer Question

Tom, I have an Amana 90 furnace that will run but not bring the temp up to what the thermostat is set at. It runs a short cycle 6-8 minutes and then cuts out and will try to relight for 3 attempts and go into lockout. I reset and then the same thing happens again, bad high heat sensor??? Changed filters, etc. but to no avail.
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to help answer your question(s). Please provide all the information I ask for since I'm not onsite. At the end of our dialog you will be asked to rate my service, but please wait until then and all your question(s) have been answered satisfactorily. Thanks for your business!

Have you tried cleaning the flame sensor?

Customer: replied 1 year ago.
sir
Expert:  Tim H. replied 1 year ago.

What did you clean it with, can I ask?

Customer: replied 1 year ago.
Steel wool
Expert:  Tim H. replied 1 year ago.

OK, that sounds right. Can I get full model number, please? What LED flash code are you getting when it shuts down?

Customer: replied 1 year ago.
Model # *****1-flash
Expert:  Tim H. replied 1 year ago.

Are the burners lighting at all?

Customer: replied 1 year ago.
running a short cycle 6-8 minutes then goes into lockout. I reset it and then same thing.
Expert:  Tim H. replied 1 year ago.

When they light, watch them. Do they light smoothly and all the way across quickly?

Customer: replied 1 year ago.
they do. Flame is steady blue without color change.
Expert:  Tim H. replied 1 year ago.

OK, the 1 flash code is ignition lockout. There are many things that can cause this. You may have already seen this, but here are some of the possible causes of an ignition lockout.

Expert:  Tim H. replied 1 year ago.

One thing to check is that front cover pressure switch. Is the front cover on securely when you try to run it?

Customer: replied 1 year ago.
That was my initial thought too. I will double check it and get back to you.
Expert:  Tim H. replied 1 year ago.

OK, thanks.

Customer: replied 1 year ago.
Tim - Front cover pressure switch does not appear to be the culprit. What is the best way to rule out an issue with the thermostat?
I have a honeywell 5+2 day programmable model.
Thinking that I should jump the wires and see if it stays going. It is probably not the issue, but...I have a 4 wire system, the back of the thermostat has G-W-Y-R/Rc, which ones should I jump to call for continuous heat?
Expert:  Tim H. replied 1 year ago.

If it was a thermostat issue, it would NOT lockout with a flash code. It just wouldn't be on at all.

Customer: replied 1 year ago.
Ok, thanks. I have been watching it for the last few attempt and the thermostat calls for heat, blower kicks in, igniter lights, but no fuel. I cannot hear the valve try to open. Any thoughts?
Expert:  Tim H. replied 1 year ago.

You may have a bad gas valve. Get a voltmeter and set to "volts AC" and put one probe on each of the two terminals of the valve. Watch it through a few cycles. If the valve gets voltage, but no gas, and you have good gas pressure, valve may be bad.

Customer: replied 1 year ago.
Did a complete 1min reset, flipped main and the furnace fired and ran for 7 and a half minutes then abrupt fuel shutoff. Main blower ran for 2-3 seconds and stopped. Now it's trying to restart, but the gas valve is not opening.
Customer: replied 1 year ago.
What could be telling the gas valve to close and then not allow it to open?
Expert:  Tim H. replied 1 year ago.

The valve could be getting voltage from the board, but if it's working intermittently, could cut out, hence that's why we need to confirm voltage.

Customer: replied 1 year ago.
What sensors/switches would shut the gas off, then sit idle for a period of time and then allow it to open? There is something not allowing the gas valve to open for a set period of time. It seems like the furnace operates once every hour for 6-8 minutes and then goes into lockout for an hour, runs... Any ideas???
Expert:  Tim H. replied 1 year ago.

Please start by checking voltage to the valve through several cycles. I want to confirm that we don't have a bad valve. What we are looking for is voltage to the valve (24 volts), but no gas coming out, and yet the gas supply to the unit is still there.

Customer: replied 1 year ago.
When burners light I have 24 volts, when it doesn't no power to the valve.
Expert:  Tim H. replied 1 year ago.

As long as there is a call for heat, you should have 24 volts to the valve. If it drops off, you may have a bad board.

Expert:  Tim H. replied 1 year ago.

You can try jumping R to W at the board after first shutting power off. This will simulate a call for heat when you power back up. The inducer should start, pressure switch will close and then ignitor will light and you will get 24 volts to the valve. This voltage should remain as long as you have R to W jumped.

Expert:  Tim H. replied 1 year ago.

It s also possible that the furnace could shut down if flame isn't sensed. Even though you cleaned flame sensor, it may need replacement. Make sure you have a good ground from the board to the burner area.

Customer: replied 1 year ago.
Ok Tim, I definitely follow your thought on the flame sensor. I have 24v at the gas valve. Furnace comes on runs 6-8 minutes and then gas valve closes and system tries to relight 3 times and then is locked out. Approx. 1 hr goes by and then the system starts again runs 6-8 minutes and then gas valve closes, tries to relight 3 times, lockout and then the same cycle... What changes over the course of an hour, system reset of some sort?
Expert:  Tim H. replied 1 year ago.

Yes, it will try 3 times, then go into a lockout for a period of time. Again this could be a weak ignitor or even the flame not being sensed (poor ground from board to burner area, bad flame sensor.). The problem with this 1 flash code is there are SO MANY THINGS it could be. You saw the list. I'm just trying to eliminate some of them.

Expert:  Tim H. replied 1 year ago.

Did you have additional questions on this?

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