Opens for 1 second and resets just as quick and then loses vacuum from .9 to .6 in another 4 minutes and repeats, added new switch and new press hose still doing it, pulled vent pipe and still doing it, stopped main blower in mid-cycle and still trips, vent mtr. Pulling normal amps, possible weak mtr.?

How long does the vent motor run, and what is the .9 and .6 is this the amps on that motor or the amount of vacumm.

About the 4 minute wait, if you are diagonosing and want to shorten that time just unplug the unit and replug it.

Take the vent pipe off the connection coming out of the furnace and use a vacuum hose from your vacuum and clean out all of the housing where the assist motor is. Reassemble and try.

.9 is beginning vacuum, 6 in. w.c. is the trip point, when vent gas is 1st vented the vacuum is high and as it runs longer it begins to trip, inspection of interior of inducer revealed nothing out of the ordinary, but I did not vacuum out as of yet.

Answering my own questions now.. went back today and took off ventor mtr. Assy. And cleaned and vacuumed wheel etc. etc.. . found the bearings to be tightening up and causing press. sw. trip, replaced mtr. Assy. And all is well once more.. thx. letmetellu..

You did good, on that little motor it is hard to tell when the motor bushings are slowing the fan enough not to work the switch.