Bosch oven cooling fan is continuously on at the same speed and is on always no matter what the temperature is. Upper heating element does not turn red hot in broil mode.

SOURCE: Jenn Air w30400b with F2 code

Since the elements are working fine, the thermostat seems to
be in question or, the contacts and connections to the thermostat
are loose etc. This seems to be a controller / temperature thermister problem and since it is intermittent, it might just be
bad contacts in that area of the circuits. see this description below.

INGLIS Royal 100 STOVE F1 F2 F3 ERRORS
Mode lUP 48500 ( thats eye you, not ONE U )

I got the dreaded F3 error on the Display Panel,
every time I pressed BAKE or BROIL, BUT, I could
hear the three relays click in, and then kick out in
sequence, just before the F3 appeared.

I called Westinghouse ( that services INGLIS ) and
was told that F3 " means unpug for 1/2 hour and then
press CLEAR 5 Seconds to reset ". Which is nonsense.

All functions on the clock and timer work fine, and the
three relays were working, so its not a computer problem.
I called service REPAIR companies who said it was the
THERMOSTAT, and replace it - $147.99 ... The Glass tube
of the display is $200 with no circuit board, the relay board
is $300 and the computer/display is $400.

I did tests on the thermostat, first heating it with a propane
lighter, and it raised from 475 Ohms at room temperature,
to 600 ohms, so I knew it was functioning.

Then, I plugged in a variable resistor where the thermostat
plugs in. I went from Zero Ohms resistance to 5000 Ohms in
200 Ohms steps.

Zero Ohms ( equal to burnt out or unplugged) gives you
an immediate F1, which you cannot clear.
From 100 Ohms to 400 Ohms, you get Error F2, which
means thermostat too low.
From 400 Ohms to 665 Ohms there is no error.
At 665 Ohms, the BAKE will beep twice, stating that you
are setting the temperature at or lower than the actual temperature
of the oven ( you cant set the oven at 200, for example, if it is
already at 450 Degrees )
Using this 2 Beep code, I raised and lowered the resistance
and made a graph of the reading on the display versus the
OHMS that the thermostat would send to the controller:
665 Ohms = 170 Degrees Farenheit, which is the
lowest reading in the BAKE MODE.
800 Ohms = 240 Degrees
1100 Ohms = 380 Degrees
1400 Ohms = 500 Degrees, which iis the maximum that
the unit showed in the BAKE MODE.
1430 Ohms to 2750 Ohms, there was no reading, an NO ERRORS.
ABOVE 2750 OHMS, the F1 ERROR appeared again, meaning
thermostat out of range.

Note that the computer module supplies 5 volts DC to the thermostat,
to see the changes in current with changing resistance.
You can easily check the thermostat to see if it is OK, with an
Ohmeter across the thermostat, which should read about 475 Ohms
at room temperature. If it reads Zero, it is burnt out. If it reads
over 2750, it is defective. Check to see if the thermistor in the
tube is SHORTED to the steel outter case as well, as this should be
infinite ohms ( no contact )- if it reads ZERO it is shorted to case.

I found that on the Internet, there are hundreds of people looking for
the F3 code for the ROYAL 100 ( model number IUP 48500 )
and a general search shows that for 400 " other" models of all kinds,
F3 = REPLACE THERMOSTAT ! Not on this model, and all typical searches
for technical support or diagrams or troubleshooting did not even list
the Royal 100 AT ALL, as if it never existed.

I then did tests on the relay board, and replaced the capacitors, a few diodes,
some resistors that were a bit out of value, and two transistors that were
a bit out of value. There was no change in F3.

I cleaned the contacts on the three relays using a typical board fingernail
file that ladies use for their finger nails ( I keep a supply for cleaning
relay contacts, since there is sandpaper on both sides, and they are
tiny enough to fit between most contacts ). THEN, I realized that the BROIL
contacts were bouncing apart - they were too far apart, and not closing
properly, so I bent the stationary contact a bit closer, and plugged in the
stove = NO ERRORS..

I analysed the circuit, and after turning on the 3 relays ( NOTE, when you
turn on BAKE, as in a regular oven, THE BROIL ELEMENT goes on at first
to quickly help the BAKE element get the oven up to temperature )
there is a feedback circuit that feeds 250 Volts back into the 5 Volt computer
chip ( ! ! ! ) It uses two 22 Meg Ohm resistors in series for a total of 44 Million
Ohms, which shows about 46 volts accross the resistors. Since the gas
tube display uses 30 volts to light up, the 46 volts is within the computer
board's ability to lower it enough to feed into the computer. There are transisors
on the back of the control board and Zener diodes etc. to " compare " the
voltage, where 46 volts in = 250, and Zero volts, means that the element
is burnt out, the element fuse in the fuse panel is burnt out, or, the relay
contacts are dirty. The relays are absolutely standard 24 volt relays,
with a plasic cover that snaps off if you pull and wiggle it. You will see
the round silver contact pads are blackened and probaly pitted.
Sand these flat until silver/brass shiny, and test to make certain that
when you press the metal lever that the magnetic coil pulls DOWN,
that the contacts touch! If they do not touch tight, bend the
stationary contact in a tiny bit and test again.

You can first check the fuses - there are two 120 volt fuses in the
fuse panel that give you 250. Then, you can unplug the stove,
and use an OHM meter to see if the element is burnt. The two types
of elements I checked were 3000 Watt at 18.7 Ohms, and 2500 Watt,
at 48 Ohms. If the elements are burnt out, you will get ZERO ohms.
If the element is burnt internally through the insulation in the tube,
and shorting to ground, between the ends and the steel back of the
stove ( ground) you will get a reading of X amount of ohms ( which
normally should be ZERO ) If the element is burnt or shorted to
ground, replace.

The F3 error is a really dumb mechanical errror of whether the 250 volts
is on the elements. It does not involve the computer or the thermostat,
or the relay " electronics" at all - it is just simply 3 contacts that supply
250 Volts, and whether or not the contacts work, the elements work,
or the fuses work. This the same 250 Volts that is on an ordinary
dial stove, and the dumbest part of the whole unit.

When I called service, they said they would order the $147.95 temperature
thermostat, and " see if this fixes the problem", if not they would start
replacing the modules - $300 and $400, plus labour, plus tax etc., and
since the problem was on the module, this would cost $147.95 + $300,
plus $75.00 for the first 15 minutes, and $15 for each additional 15 minutes,
for a total of about $466 dollars ( CDN ) which is about $460 dollars US.

A package of 25 fingernail files is $1.00 at the dollar store. That is all that
it cost to fix the problem. You need a square ( Robertson ) head screwdriver
to remove the 7 screws on the back panel, and then you wiggle the
covers off the relays, and clean them. It takes 10 minutes.

good luck ! Damned the manufacturers for not putting this information
in the user manual.

Robin Graves, January 2008, kidbots.com

Bill Dickerson

• 979 Answers
• Posted on Jan 30, 2009

SOURCE: Heating element on upper oven of a wall Thermador Oven

The control switch may be bad on it. If there are 2 elements on the top, they both are not bad at the same time.Check to see if the wires have not burned off the control switch first. Check to see if your breakers are O.K. Turn them both(maybe 3) off and then reset.

SOURCE: GE JTP 1580W288 Set oven to Bake, switches to broil at bake temp

The F2 Error code means the oven has detected an excess temperature condition. Most often this is due to a bad temperature sensor - the sensor costs about $75 from an online repair site. 
How to remove and replace the temperature sensor. In most GE ovens, when you open the door, you'll see the rod-shaped temperature sensor sticking out of the back wall at the upper left. It's about six inches long and a bit more than 1/8" in diameter, held in place with two screws. 

Turn off the circuit breaker (built-in ovens) or unplug the range before attempting the replacement. 

The replacement sensor will come with instructions, but basically it's a matter of removing the sensor, pulling out the wires to where they are connected and disconnecting them. You may have to snip. The replacement sensor will come with high-temp wire nuts to hold the new connection. Polarity doesn't matter; it's a straight resistance thermocouple. Hook it up, be sure you poke the connections back far enough so that they're on the other side of the thermal insulation and not resting against the back of the oven. 

If you continue getting the F2 error after replacing the sensor, then the problem is likely in the control module - this is the circuit board behind the keypad and clock. 

You'll need to remove the decorative bezel to get behind the control panel. Remove screws and set off parts in order - it's not complicated. Once the bezel is off there are two more screws that hold the panel in place. Then you can lift the panel up about a half inch and pivot it forward toward you. You'll see a bunch of wires going to a circuit board. 

On the panel you will notice some black plastic boxes that say "Potter & Brumfield" on them. These are relays. Check the relays - slide the black plastic cover straight up to expose the coil and the contacts. The coil, when energized, closes the contacts - look at all the relays. You can manually close the contacts with your finger (be gentle). If the contacts of one of them are stuck, they might be welded together. You can fix the problem by prying apart the welded contacts gently with a knife blade. Take some time to gently polish the relay contacts with a folded bit of fine grain sandpaper - this will get some more life out of them. Be gentle and careful - the relays aren't complicated but if you bend the contact or rip it out, you'll have to replace the controller, which will set you back a couple hundred dollars. If you unstick and burnish the relays, they will probably eventually weld together again as the rough spot will spark, but when you burnish them with sandpaper they should be good for some more life before they need to be replaced. 

If the problem isn't the temp sensor or welded relay contacts then the problem is obviously somewhere else, but temp sensor and relay contacts will account for the lion's share of F2 errors. 

Once again, be safe, be careful, be gentle. Ovens are not very complicated and they're tough, but always exercise care. Always disconnect electricity before messing with them.
good luck,

SOURCE: Upper Oven doesn't heat in bake or broil. Lower /Ctrl panel OK

check to see if both ovens are the same circuit if they are you have a internal problem with your upper oven internal circuits or damaged wirering contact a qualified service tecnitian

SOURCE: The upper heating element does not get hot (red)

It's not broken. It is being controlled.