Big Maxx no fan

[ROCKNMUD]

I have a 40K BTU Big Maxx heater and it has worked great for many years but today my shop was cold.
The unit fires but the fan does not turn on to blow heat. It must trip a sensor as the unit shuts off instead of the fan starting.
I then remove power for 5-10 minutes and it will start again but no fan.
The fan does spin by hand with no power. As for the LED codes it is fast flash.
Thoughts?

 

[BurtEggley]

know how to use a volt meter? See if the fan is getting power or not. Could be a bad capacitor, bad fan, bad relay etc..

 

[Chuckster in NJ]

Can you "jump out" the limit switch and see if the fan starts?……. "IF" it starts blowing you have a bad limit switch.

"IF" the blower doesn’t start (after heating up) the unit is most likely shutting off due to a high temperature.…… This is a safety feature.

 

[fitter30]

Taka pic of the wiring diagram. Need to see if it cycles on of by time or temperature.

 

[ROCKNMUD]

Here is the requested picture

 

[ROCKNMUD]

I do get a click sound when the fan should turn on but no power present where the fan connects to the board.

 

[PoorUB]

I do get a click sound when the fan should turn on but no power present where the fan connects to the board.

Toss a control board in it. Before you do that I would make certain the fan motor is ok by connecting it directly to 120 volt and see if it runs. The motor may have failed and killed the board.

 

[ROCKNMUD]

I did test the fan and it works. I have ordered a new control board and will update once it arrives.
Thanks for all the advice!

 

[ROCKNMUD]

I installed the replacement control board. It definitely needed it looking at the burn mark on the back of the board.
Now the unit fires but as soon as the igniter/sparker stops clicking the flame goes out. It will do this 3 times then shows a 2 flash code for system lockout, failure to detect or sustain flame.
I assume the fried board damaged another sensor?
I hate to throw parts at something but should I replace the flame sensor next?
Thanks for all the help!