Question about Bosch HBN 455 Stainless Steel Electric Double Oven
We recently moved to a house that has a Bosch HBN 455 double oven installed. I've noticed that after we have finished cooking (so far only in the top oven), the oven's cooling-fan repeatedly cuts in and out for some time afterwards. I'd expected the fan to stay on, but ours cuts in and out as often as every few seconds, barely getting up to speed before slowing again... and then restarting (sometimes almost immediately, sometimes after a few minutes). Between each change in state I can hear a slightly buzzy electrical click, which I guess is a thermal switch triggering all this. It all sounds kinda odd -- I had assumed that the cooling-fan would simply stay on until the oven had cooled to a certain temperature... and that THEN the thermal switch would trigger (which is how the newer Thermador oven in our old home behaved). Is what we are experiencing normal behavior for this particular Bosch oven? Or is there likely a fault? Many thanks.
After the oven is switched off, the after-run of the cooling fan is controlled by an electromechanical thermostat switch. The fan can switch back on, due to residual oven heat that accumulates within the oven's outer case and reactivates the cooling fan temperature switch. Considering yours is making buzzing sounds and activates on and off, the fan's thermal switch may have dirty contacts or just be defective and require replacement.
Posted on Oct 02, 2007
Our HBN655 had similar issues- the upper cooling fan would cycle on and off on a relatively quick duty cycle until the whole mess cooled off enough and it shut off.
My workaround is to turn the temperature dial off but leave the oven function dial on to BAKE. This seems to force the fan to stay on; then we shut it off a while later and avoid the annoying fan cycling.
(note- 2 years ago, our fan became intermittent, varying speed, etc... for about 2 months before it quit entirely. When that happened, the oven started to heat then the thermal cutout kicked in and the oven shut down entirely. We ended up replacing the fan and that fixed the bug... except now it's starting to act up again...)
(also note- the racks on this beast have a faulty design. if you have a heavy casserole and slide the rack out all the way, it tends push the sidewalls apart and the rack drops. I spoke with Bosch about this and they sent me new racks, no charge... so they know there's a problem. But the new racks don't fix the bug; they just make it harder to reproduce. I have actually had one rack fall with 2 piping hot casseroles on it. Fortunately no one was hurt.)
Posted on Nov 04, 2007
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