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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8258
Experience:  Furnace, A/C and heat pump specialist.
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I have a Furnance, model 395cav048111. The Thermostat starts

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I have a Bryant Furnance, model 395cav048111. The Thermostat starts to turn the inducer fan and then the glow plug turns red, but not gas comes through. It goes through this cycle a number of times before it quits.

I am about to leave office tonight but it sounds like we have one of three problems.

1.Board is not sending voltage to gas valve.

2. No gas supply to valve

3. Gas valve is defective and not opening

Customer: replied 8 months ago.
it randomly works. Sometime it does come on and other times it does not.I do have multimeter if needed.Thank you

First step when it does not work is to check for 24v at valve as ahown below when igniter lights.

If we get 24v but no gas we have either a pressure problem or bad valve.If not a failing control board

If we are getting 24v and you are confident you have good pressure to valve or have a manometer or pressure gauge to verify, replace valve.

I have to leave tonight but will be back in the morning.Would you like to check these things right quick before I leave? Or can we continue tomorrow?

Customer: replied 8 months ago.
If the attached pic is the correct wires, then it is reading 14 volts as I touch each of the wires. When the igniter light comes on the voltage jumps to 26 volts. I pulled the green wire off as I was checking. After I checked, I place the green wire back on and then the gas came on and the heater kicked in. So I am not sure why sometimes it kicks on and other times it does not.let me knowRick

Make sure the conctions are clean and secure.,If it gets 24v everytime the solenoid is sticking in gas valve.If not issue will be a failing board. Often when board starts going bad it will be sporatic.I am leaving for the evening but will check in with you in the morning. If i

Customer: replied 8 months ago.
Chat tomorrow.thank youRick
Customer: replied 8 months ago.
When you get this tomorrow, is there a way to check the sticky valve or if the board is going bad? Or do you have to replace one, and if not fixed, replace the other?Do you have parts for both of these items?Thank youPS: It would have to happen the first snow fall of the year.
Customer: replied 8 months ago.
I did more testing tonight and attached my multimeter to the two wires connecting to gas valve. Each time the glow plug kicks in the volts jump from 14v to 26v and then back to 14v. I also used my amp detector to see if there is a draw when the 27v kicks in, and there is.Out of 10 tests to ignite the gas, it ignites 4 times. The others failedThat is my report.Rick

Good morning Rick.AS for checking to see which is the issue.You have done this.

" Each time the glow plug kicks in the volts jump from 14v to 26v "

That tells us board is doing its job.

Valve is the culprit that is not responding every time.

I do not have the part number but there should be a label on valve like a 36C03-300 or similar.

Customer: replied 8 months ago.
The only label that i find on the valve is on top of the valve (not the large metal piece that the gas line connects to) is:
36E 24 209
Press Max 1/2 PSI
3.5" WC
.3Alet me now. If I need to replace the whole gas valve, do I nee dot have someone do this? Or is this something that I can do. I worked for the gas company 30 years ago.Let me know if you know where I can purchase the valve from.Thank youRick
Customer: replied 8 months ago.
Just a quick question on this part. This is the gas valve part that is part of the whole gas valve assembly. Should just replacing this part take care of the issue, or does the whole assembly need replacing?Let me knowThank youRick

Yes Rick you will replace the whole gas valve .They are not considered field repairable.It will come complete as pictured at link I sent.

Customer: replied 8 months ago.
Ok, I just ordered the new gas valve. I will keep this opened until I get the valve replaced to make sure I don't have other questions/issues come up.Thank youRick

No long as question does not time out we are good.If you are happy to this point, you can rate now and that keeps from timing out.You still have 30 days to follow up after rating at no cost.

Customer: replied 8 months ago.
When replacing the gas valve, do you recommend using the pipe dope or the teflon tape rated for gas?Thank youRick

Personally I have never been a fan of the Teflon tape although many like it because of the no mess use.I prefer rector seal pipe dope.

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