MiniMax 400 NT/ LN blower last leg?

[jimshew]

I've been rummaging through all the old postings on the troublesome ancient MiniMax NT ... This one was working "fine" until massive rains, now:

On the 6800 analog dial control panel ...
* Shows TFUSE light
* Does NOT show a PV light
** I checked the vacuum sensor and tubing, seems to work as expected
** *Might* have a gas supply issue-- can't smell any gas

All switches and sensors replaced recently. I realized the blower speed is slower than it was originally, don't hear an ignition attempt at all, blower just keeps blowing at a less volume than it used to ... currently thought is more likely to be blower capacitor or ignition module than the actual gas valve. I was close to tearing out the burner tray and all that to clean it, but maybe somebody has a different idea based on the blower running slow?

 

[ajw22]

Blower running slow may be the bearings in the blower getting corrosion and friction. The blower motor is not very powerful to overcome any friction.

@swamprat69 may have thoughts.

 

[swamprat69]

Helps greatly if you have the appropriate test instuments. Check that the capactitor is within + or - 10% of the stated rating. Check that the amp draw of the motor does not exceed the rated FLA of the motor. Spin the blower wheel. It should move freely and slowly come to a stop. Even if it moves freely, it should not spin and come to an abrupt stop. It is OK for the motor/wheel shaft to have some play along the axis of the shaft, but should have no play opposite the axis of the shaft. Check that the pressure that the pressure that the pressure switch is seeing exceeds the stated set point for the pressure switch.

 

[jimshew]

The capacitor checked out OK, even though it looked like something from FallOut ... all rusty and steam punky ... turns out the bigger blower wheel was barely there, it was turning, but only 1/3 of the time because the half of the rusted blower wheel was always making contact with the other half. Apparently the last two big rainstorms just had water sitting here and it fell apart completely as I removed it. Got exact replacement, used blower+motor for $120 including shipping (didn't trust the rest of the motor, even if I could find a workable correct blower fan). That did the job. Apparently my jerry-rigging around the vacuum switch wasn't good enough, she's burning now!

So I figure that might have bought me another year, two tops ... while I enjoy the Fallout vibe on this thing (heat exchanger both rusty and blue/green from build up), I have low expectations and expect the heater to be the first thing goes out again ... So as far as tribal knowledge goes, trust the design of the serial lights to find the first failure, not enough air flow and no PV light was indeed spot on -- not enough air from blower.