Blodgett DFG-200 Low Fan Oven Mode Not Working

[fixbear]

That shows manufacturing date of march 1 1994 and a bottom oven, 14th built

The 54447 is the right switch

[fixbear]

be aware, that Blogett had 2 different 4 position switches. 20347 and 54447.

This is the switch positions FOR THE RIGHT ONE by the wiring diagram.

Header 1 Header 2 Header 3 Header 4 Header 5 switch position L1-1 L1-4 N-2 N-3 OFF O O O O COOK HIGH 0 X O X COOK LOW X X O X COOL DOWN O O X O

Either way with the cool down L! will work. one high, one low

 

The cook and hold one does this

Header 1 Header 2 Header 3 Header 4 Header 5 Switch position L1-1 L1-4 N-2 N-3 OFF O O O O COOK O X O X COOK AND HOLD X X O X COOL DOWN O O X O

 

Note that the hold would cause a problem.

[fixbear]

FWIW:  I’m questioning that schematic because it isn’t making sense.  I’m not seeing line going to the motor during low speed.  Their illustration of the 4-position rotary switch leaves some questions.

 

That’s because the N terminal goes around through the temp, time controller.  Both poles of the selector switch are not connected, but independent.  In low cook  L1 powers both 1 and 4 to drop the motor relay to low powering motor terminals 5 and 6 instead of 1 and 2.  Or if you prefer, motor plug pins 6 and 12 are high motor.  Pins 3 and 11 are low.  Pin one is the capacitor to both start windings.  They connect to motor terminals 1 and 6 threw the start winding’s.

[fixbear]

didn’t come out of a prison, did it?

[fixbear]

You  can easily test your old switch to confirm if it is the problem.  I suspect that the relay coil or a plug is what you will find.

[guest]

I’m coming late to the party, here. Why did you feel the switch was bad. I was wondering if maybe the low speed windings, on the motor, had failed.  Intermittent high speed problems can also be the centrafugal switch, in the motor, starting to fail. Belive me, this one has caught me once or twice, too.

[ectofix]

Thanks for your input, rico.  However, in this application (convection ovens) the centrifugal switch doesn’t have anything to do with starting the motor.

The centrifugal switch is normally OPEN – and then closes when the motor reaches operating RPM.  This energizes the oven’s heat circuit.

[fixbear]

In all my years of working on food service, I have never seen a open winding on a convection oven.  Nor a shorted winding.  This is due to the high quality of insulation required for the heat and the high power factor for all the starts that a oven goes through.  Now bearing’s,and proofing switches,  that’s a different story.  Anyone have a different experience with them?

[guest]

Unfortunatly, I have seen both, otherwise I would not have mentioned them. I have had the low speed windings fail on two Blodgett unit. Granted this was over a 10 year period with four units in each of my twenty five restruants, so a pretty low number. But its the odd ball ones that usually trip us up 

As for the switch I have had bad motor proving switches that would intermittently drop out the heat. You could turn the unit on and, no heat. Open the door, close it, and now its heating. Out of all those ovens I only had to replace three selector switches.

 

I must have missed something. It was not clear, to me, if he was saying that it would not heat or that the blower motor would not run, in high.

[wired1000]

Hi Folks,

 

I really do appreciate the advice and ideas.  Just returned from vacation

and had a pile of spare parts available to me that had arrived while I was

gone.  Luckily, first one did the trick.  I replaced the 4-position switch

with the correct # and everything is working fine again.  It must be

something about the internal wiring of that 3-position switch that wasn’t

allowing the low fan mode to work.??

 

Anyway, thanks again.  Glad it was something simple…