I have an Amana PBH113A35MA the unit will not turn off even when I set the dial to off, the fan keeps blowing. Every thing else works fine.

The most likely things, in order, are:
1) There is too much dirt, dust or lint clogging the squirrel cage fan, slowing it down and causing the motor to overheat and shut off.
2) The motor is clogged with dust or dirt and is overheating and shutting off.
or 3) the ductwork is clogged, causing the motor to overheat and shut off.
God bless your efforts.

The magnetron is more than likely the problem, or the inverter board if oven is 7 years old or less. If you have a digital meter you can do a rough test on the magnetron, unplug microwave, set meter to ohms, disconnect one wire from magnetron and put the test leads across too points, if reading is .2ohms or less it is good, but if the test shows infinity or open the magnetron is bad, keep in mind it may have a short making the reading misleading.

Sounds like you might have a leak in the sealed system and it is gradualy getting worse.

If you do not have guages (freon) and have a licens to proforme this type of work you will need to have someone qualified in this area to varify.You can call sears home repair @ 800 469-4663

check your circuit breaker.

You could also try defrosting the unit completely.

Dust on the inside of the unit can cause the overload switch to shut many vornados down. Blowing the dust out of the unit with compressed air or a blower may help.

Another problem that causes vornados to stop working (light on - no heat no fan) is when one of the bearings starts to go bad in the unit. This causes the fan to be slower and less effective and the unit’s inability to move the heat away from the thermal overload switch again causes it to shut down.

Though you could remove the front and rear bearings and try to get replacements if it's even replaceable ... Once the bearing starts to go bad there is little that can be done ... HOWEVER, here is one solution to get more life out of the unit.

First, use a blower to blow all the dust out of the unit.
Then, because it is typically the front bearing that goes bad first, lay the vornado on it’s back (so the unit would be blowing air up toward the ceiling), this will relieve the front bearing somewhat and rely more on the rear bearing which tends to last longer.

The vornados I’ve had are all thermistor units ... that is, they don’t just turn on and off when the set temp is reached but in fact slow themselves down (both heat and fan) to keep some level of air circulation in the room. This is a good thing by the way.
There are usually two toggle switches .... one is a heat switch - usually Low & High .... the other is the thermistor switch (this sometimes is labeled “fan”) - usually Auto & High.

Once the unit is on its back ... Now, change the settings as follows:
Turn the Heat switch to LOW
Turn the Fan switch to HIGH
Turn the dial (with the temperature in degrees on it) to the lowest setting - which is somewhere around 60’ish.

Now turn the unit on and it should stay working.
Three things that could cause it to turn back off ...
You turn the Fan switch back to Auto.
You turn the Heat switch back to High
You turn the temperature selection dial too high ... though, you can cautiously turn the dial up a few degrees at a time ... the unit will start shutting down again when you set the temp too high ... then just dial it back down ... unplug for a couple minutes, then turn back on.

Sometimes too much dust around the heating elements can cause the heater to switch off to prevent a fire. Check for dust build up first. You can try using a can of compressed air that can be found at many electronic stores.

check freezer for frost build up and if FAN is blowing, check condenser, make sure its clean, and fan blowing, check vents in refrig. make sure no blockage, controls should be in the middle setting, make sure u didnt turn up freezer control cutting air supply to refrigertor side should be 1/2 feel vent coming from freezer see if you feel any air coming in to refrig.

Reset the unit to factory setting by take the master switch off of 10 sec.
Then press and hold the cool and heat button down while turning the master switch back on.