Hello,

My carrier furnace is on the fritz. I am receiving a 34 code which states"ignition proving failure"
The blower fan starts and the hot surface ignitor lights but no gas flows. I replaced the ignitor with a new one-no help. The flame sensor is clean.When I check voltage at the gas valve connectors I see 12V. Is this the problem? Should I be seeing 24V?

Any help appreciated

Yes, normally you should see 24VAC. Is this the first time you started the system up this year? Some times these valves will stick. Try tapping on it while it is in a call for heat.

Hi Mark,

Actually it's seeing 15V. What's my next step if tapping on gas valve doesn't work? Possible flame sensor? How do I test it?

Thanks

Eh if you're not getting ignition then the flame sensor isn't going to make a difference. It only proves ignition.

Well I just noticed voltage to gas valve is at 15V *prior* to ignitor lighting up. When it does light up voltage jumps to 28v. Sounds like I need a new gas valve

Sounds like a good decission.

Hey I got same problem BUT when I tap on gas value it clicks then lights. It might run for a couple days then it starts all over again. My question is can I take apart and clean gas valve?

My question is can I take apart and clean gas valve?

NO NO NO NO. Got the idea yet. That is a super big no.

Even if you have the proper tools for the special screws there are no gasket kits or parts available. It is far to dangerous to try to reuse one.

Now I do take one apart once in a while but that is for class just to show the people what is inside and how they work. After the class is over it is tossed in the garbage can.

Before they started to use the special tamperproof screws back in the 60's people would try and repair them. They even had a few rebuilding companys but after a few fires and explosions they all went out of business. Way to dangerous to try to fix.

hvac1000 said it. NO NO NO No. Buy a new valve and live. It is not like a carburator on a vehicle. They are not rebuildable.