Unit : Intertherm / Nordyne, forced air , nat. gas furnace - about 15 y.o. : Mod # XXXXXLately, this unit seems to be ' re-lighting' [ cycling on and off.... during a normal heat cycle] too frequently.I replaced the ' scorched ' flame sensor ; installed a new Honeywell , non-progammable , digital wall-mounted thermostat .... to replace the original 'mercury/bulb' old style thermostat ; replaced/installed a new ' dust-filter' in the return air duct ; vacuumed out the interior of the furnace ; and replaced a cracked hose that connected to the pressure/vacuum switch.... after seeing the red blinking light , on the p.c. board , flashing.... " twice " .. indicating a problem with that part.Original problem... still exists !!!!!!! Or....should this furnace ' re-light '.... more than once or twice,more .... during a normal heat cycle ???Do I need to replace the entire p.c. board ; the pressure switch ; the various limit [ button ] switches.... or just up-grade... with a new furnace???This unit also has a central air system..... installed with it.Thanks,Ron
Hello and welcome to Just Answer. I am servtech50 and will assist you today
over 20 yrs. experience
What Happens Now?Your chat has ended, but you can still work with your Expert to get an answer to your question if you have not yet received one.Come back to this page at any time to see additional information from your Expert. You will also receive an email when your question is updated. If you want to send a message to your Expert, use the box below.If you have already received a satisfactory answer to your question, click the Accept button above. Experts are credited for each accepted answer they provide.
Where / What is your ' response ' to my inquiry ????
Sorry for that I switched to Q&A. is this Furnace a condensing furnace? try to find manual but no luck. if so clean out condensation system from drain hose to trap to furnace. If not, turn furnace on, (call for heat), when venter motor starts and running at full speed connect the two wires going to pressure switch together and see if unit continues to run. When you changed the hose did you clean out the nipples that the hose connects to also?
Also do you have a meter that we could check some voltages? would like to check pressure switch while unit is operating.
Thank You for these ideas.Not sure about this one being a ' condensing ' furnace??? It has the a/c " A " frame condenser unit.... sitting above the furnace...in the enclosed [ ducted area ] air stream that goes to each room....???I;ll check the condensate drain line that leads from the water catch tray... beneath this " A " frame.... to the floor drain.... to make sure that it is... free-running.YES... I have an electrical test meter.... and would welcome some voltage or Ohm numbers... for the pressure switch.I'll ' activate ' the " Accept Answer " button..Thank You for your help.Ron
Please leave electrical test meter Voltage and or Ohm [ required ] readings.... for my pressure switch testing .... on my email ..... I need to leave , now , for a business appointment.Thanks , again... for your help,Ron
thanks for the accept. But in the future please do not accept until you are satisfied with the results. If you do have a condensate furnace there will be a hose coming from the furnace its self. the a/c coil will also have a hose or piping. So if there isn't any hose or piping coming from the furnace to floor drain then you do not have a condensing furnace.
Now to check pressure switch......with furnace on but "NO" call for heat.......check the two wires going to pressure switch, check each one to ground. one wire will have 24 or so volts and the other no voltage. and if you check them one to the other you should also get 24 volts. now with a "call" for heat..... if you check the wires one to the other you should get 0volts when the pressure switch closes. if during the call for heat cycle the pressure switch opens you would then get 24 volts. If this happens then you know that the pressure switch is opening during the heat cycle. During the first check of wires to ground one has 24 volts the other should not you could also just monitor the one that does not have voltage when there is no call for heat. you will start with 0volts and when the pressure switch closes you will have 24 volts. if switch drops out you will go back to 0. If this happens we need to figure out why pressure switch is dropping out. could be bad switch, intake or exhaust (venting) condensate (if you have this).