Bosch HBL3450UC Wall Oven - PCB Cooling Fan - Intake Location?

[baumgrenze]

I am doing due diligence preparation for a future repair.

Cleaned the cooling fan in the PCB compartment of our Bosch HBL3450UC when the PCB board failed. I did not check out the source of the "fresh air" intake for the cooling air. 

The fan was greasy, as though the air intake might pull hot air from the oven. This does not make sense to me since it is a 'cooling fan.' I've looked and I can't find a cross-section view of this part as installed.

Masters, what is the source of the 'cooling air' for this fan? 

Why was it greasy?

thanks

baumgrenze

 

[LearningTech]

 Usually takes air from below the door and exhaust above or below.

 Air comes from room and goes to room. 

 Gets greasy from room air,  it just that you clean everything else, cause you can see it and the fan you do not see. But a ceiling fan or other in the kitchen will get greasy the same way. If not cleaned and ran long enough

[baumgrenze]

Thank you for your explanation. It makes sense that 'low down' should be cooler.

I looked more carefully. This oven has a horizontal vent across the top of the oven that vents into openings at the top of the door. The air flows down the door and out of vents at the bottom.

If you look carefully with a good flashlight you can see what must be the exhaust side of the squirrel cage. It is on the left and at the back and projects down over the top of the oven chamber exterior.  The linked image was shot with my iPhone 5 through the leftmost slot while my assistant lighted it with a good flashlight. The items to the right are part of the powered latch lock for the self-cleaning feature.

https://imgur.com/a/ziMM5x4

We found it 'interesting' how much dust had accumulated around the vents in 8 years but we saw very little grease. Perhaps the mess I saw on the fan was only dust. The control board replacement was done by a certified independent repairman.

If it is dust, I wonder if one could clean the blades of the fan with a length of copper refrigerator tube with a vacuum cleaner sucking on the other end?

thanks for your interest,

baumgrenze

[LearningTech]

Canned air. Is ok to clean it with, generally its too stuck for vacuuming.

[baumgrenze]

Thanks for the suggestion.

baumgrenze

[LearningTech]

Your welcome