Pressusre switch ??

[ed7978]

HI guys...
I have a Nordyne/Intertherm Model number M3RL-060A -BW.
Pressure switch question:
About once a month my furnace doesn't get past the purge fan(inducer) phase of start up. According to the manual, it's probably the pressure switch, but why would it not work once every 400 tries?
I take all the tubing off and check it, put it back together and everything is good for another month.
The tubing runs from the purge fan to one side of the pressure switch, and from the other side it runs down to a tee and then heads off to the combustion chamber and the gas valve. Once I forgot to hook the tubing up to the gas valve and the furnace ran fine for a month or more. What exactly does that tubing do if it doesn't seem to phase the operation of the furnace????
Thanks...
ed

[Robert]

Hi Ed,


The tubing is the pathway by which the air pressure is detected and monitored for the pressure to open and close.


They can get moisture, trapped air debris, etc.. and sometimes just removing and putting back will help.


With it doing that every month and operating w/o being hooked up completely, I would have a Tech come test the system to see if anything is wrong.



Thanks,
Robert