How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Rick Your Own Question
Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 20355
Experience:  40+ yrs. experience as a licensed oil & gas technician.
94766
Type Your HVAC Question Here...
Rick is online now
A new question is answered every 9 seconds

The furnace goes thru it's calls draft motor on ,purge,

Customer Question

The furnace goes thru it's calls draft motor on ,purge, igniter,burner lights stays lit well over 20 sec,flame sensing led is constant the the gas valve clicks several time like it's trying to close some time it stays open and it run
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.

Does the 24 vac drop out at the gas valve when it shuts down? What are you getting for a flash sequence on the board LED when it shuts down?

Customer: replied 1 year ago.
Not sure didn't check gas valve vacation and the flash sequence just shows 1 hour lock out
Customer: replied 1 year ago.
Vac sorry
Expert:  Rick replied 1 year ago.

You need to check the gas valve voltage, also check the condensate drain on the unit. If it's clogged up the condensate backing up can cause apparently unexplained lockouts.

Customer: replied 1 year ago.
If the gas valve voltage drops off does that lead to a problem with the valve going bad . because the unit will heat after I have reset it once it reaches temp shuts off then room temp drops and heat is called for again it starts shutting on and off again
Expert:  Rick replied 1 year ago.

The voltage dropping out shouldn't affect the gas valve but it will indicate if the problem is with the valve or something else like a clogged condensate drain. These weird intermittent problems are often caused by a condensate back up. Could also be bad connections too. So you could also check all the connections.

Customer: replied 1 year ago.
OK I will do that.One more thing the trouble shooting guide say that after all check have made at flame sense that it may be the ifc
Expert:  Rick replied 1 year ago.

This unit has a blocked drain switch, similar in shape to the draft pressure switch and attached to the condensate drain (lower left). If the drain backs up this switch will shut down the unit. A bad board is always a possibility but it's a pricey replacement. Best to eliminate all the other (cheaper) causes first.

Customer: replied 1 year ago.
OK I can see when unit calls for valve to open it has 25 volts it then drops off.i am going to check for any block on condensate drain if I find no blockage where next
Expert:  Rick replied 1 year ago.

Try jumping the drain pressure switch

Customer: replied 1 year ago.
OK no sure how to jump switch
Expert:  Rick replied 1 year ago.

Connect the 2 leads on the switch together. Did you remove the tubing that connects the switch to the condensate trap? was there any water in it?

Customer: replied 1 year ago.
There was water in the trap cleaned all hose
Expert:  Rick replied 1 year ago.

There should be water in the trap

Customer: replied 1 year ago.
OK yes water in trap
Customer: replied 1 year ago.
What am I looking for when I jump switch
Expert:  Rick replied 1 year ago.

See if it it shuts down prematurely

Customer: replied 1 year ago.
Jumped switch got a code 4 blinks book say that means switch closed
Expert:  Rick replied 1 year ago.

Wait until the inducer fan starts up to jump it

Customer: replied 1 year ago.
Thanks will contact you again
Expert:  Rick replied 1 year ago.

You're welcome