Quadrafire Classic Bay 1200i Vacuum Switch/hose help

I was hoping someone here can help me diagnose my stove problem.

I have a 5 year old Quadrafire Classic Bay 1200i, installed by the stove dealership, and ran well with no major issues until this week. Use about 4-5 tons a year.

The Combustion (exhaust) fan bearings started to go bad. A replacement is on order, will arrive later this week. The fab completely seized during operation the other night, but the stove still delivered pellets. I shut it down, and all seemed fine. Since the stove is my primary heat source, I was fortunate to find a spare fan from a friend.
Cleaned it up and installed it. Had to reuse his gasket, but it is in good shape. Powered up and the temporary combustion fan ran fine, had the red feed light one, but no pellets. Hit reset to see if that fixed, but to no avail.

So that's my problem. What I've done so far:
Based on some other posts, I checked the vacuum switch. It appears to have power because I can jumper the switch and the unit will deliver pellets. Check the vacuum hose line and tried to blow it out, but to no avail. Can this line get clogged (at the stove side?) I tried some compressed air also (60 lbs), but no luck there either.

What's my next step? I don't know where the other end of the vacuum line is, or how to get to it. If I was able to blow through the line, I would suspect my gasket isn't as good as I thought, but looking there, it doesn't seem to be a leak (Hard to tell with the two external impellers). I also do not believe my exhaust line is blocked to prevent a vacuum, so I'm focusing on the vacuum switch. (hopefully that is correct)

(also, since it is an insert on an elevated hearth, space is kind of tight to trouble shoot: to get to the back, I can't open the hopper lid, and vice versa.)

Any help or guidance is appreciated. Thank you.

Doug Doty said:

If you cannot blow through it it is likely plugged at the stove end, and you just have to get to the end that pierces into the firebox area. Something else and this does not happen on it's own but these are often very soft silicone tubing and I have twice monkeyed around and put a kink in mine and it prevented vacuum from reaching the switch. I think your on the right path. You might try a flash light and a mirror and looking from the front side in the areas the hose is leading to, I bet you can spot it and give it a poke and then re-blow it out from the tubing side so not to contaminate your switch.

Click to expand...

Thanks Doug for the quick reply. Just struggling with finding the firebox side: whether I have to go in from the hopper (through the auger recess), from the back (remove sheet metal), or from the firebox side. I was not able to find anything on line that showed how to access is. Due to my set up, I can only try one at a time! Was hoping someone else had the same issue. Never knew how much I liked the pellet stove until it goes down!

Thanks again.

Thanks for all your help, the stove is up and running: a solid plug of fine dust in the vacuum line about 3 inches from the auger end.

I should have been more clear on my first post. I removed the vacuum line from the pressure switch end and blew towards the firebox, expecting to see a puff of dust.

I would not have thought to look at the auger for the other end of the vacuum line. Thank you kap.

I didn't fully think of the low exhaust pressure issues (took it for granted that if it was burning, it was venting). Thank you Lake Girl.

And the pellet stove is my supplemental heat, unfortunately my primary is electric baseboard - hence the stove!

This a great community with an incredible wealth of knowledge.
Thank you again for all your time/thoughts/inputs.