Tappan Furnace
#1
02-05-10, 09:13 AM
Tappan Furnace
Tappan Furnace FG6RC 120C-20C, About 5 years old --- Thermostat clicks on, induced draft fan runs, blower fan runs for about 30-seconds; then shuts down --- draft fan continuous to run --- Red LED on control board flashes a code of two (which indicates a pressure switch "stuck open" according to the info on the schematic) --- I pull the pressure switch off and blow into the air lines --- the ohmmeter shows an open condition --- How else can I troubleshoot and where can I get parts for this furnace?
#2
02-05-10, 09:28 AM
Banned. Rule And/Or Policy Violation
Time to replace the pressure switch. This is a critical safety part, and I'd replaced it ONLY with a switch specified for your furnace by the manufacturer.
Make a not of the complete model and serial number of the furnace, which can be obtained from the rating plate in the burner compartment of the furnace.
I'd shop around for the distributor who sells that brand in your area, or on line. But be sure you are getting the part specified by the manufacturer.
Make a not of the complete model and serial number of the furnace, which can be obtained from the rating plate in the burner compartment of the furnace.
I'd shop around for the distributor who sells that brand in your area, or on line. But be sure you are getting the part specified by the manufacturer.
#3
02-05-10, 04:02 PM
The pressure switch works in the opposite way that you think it does. They are normally open. Instead of blowing down that tube you must suck on it. If you do suck on it you will hear a click. Then put the hose back on the switch, turn it on and wait for that click. If you dont hear it then replace the pressure switch.
#4
02-05-10, 07:18 PM
Testing the pressure switch by blowing or sucking only varifies the switch part has the ability to close contacts. But it does not prove the reason why the switch failed to close under normal operating vacuum, and remains or goes open when running.
(Although it would prove it if you were sucking on it, and it could not close, as presumed by SP and also stated by ender.)
It can be several otherr causes, besdies the switch. Two common maladies are the 1/4 inch vacuum tube where it plugs in at the inducer nipple gets crud down in that nipple. Another cause is that condensate water is backed up. Blowing out the condensate drain lines both directions will fix the latter. There are other causes also, of course, including the switch, venting issues, something wrong with the inducer fan, heat exchanger, etc. But check out those 2 things.
As SP has often alluded to in many threads regarding thsi subject, a manometer needs to be used to deternine if the cause is the pressure switch itself.
(Although it would prove it if you were sucking on it, and it could not close, as presumed by SP and also stated by ender.)
It can be several otherr causes, besdies the switch. Two common maladies are the 1/4 inch vacuum tube where it plugs in at the inducer nipple gets crud down in that nipple. Another cause is that condensate water is backed up. Blowing out the condensate drain lines both directions will fix the latter. There are other causes also, of course, including the switch, venting issues, something wrong with the inducer fan, heat exchanger, etc. But check out those 2 things.
As SP has often alluded to in many threads regarding thsi subject, a manometer needs to be used to deternine if the cause is the pressure switch itself.
