My bladeless fan has an intermittent fault, sometimes not turning on. If I lay it down and roll it back and forth this usually fixes it. Now there's a green symbol flashing next to the speed number.

SOURCE: Intermittent Lights, Speedo, and Fan Problems

HI...
On your VOLVO 850.
The Head Lights are Relatinated Directtly with the Ignition switch.
The ignition switch send 12v. Power to the MAIN HEAD LIGHT RELAY and BULB FAILURE WARNIG SENSOR. Incorporated in the Same relay.
Very Important check the Battery terminals, And few ground Below the Battery Holder.
The turn signal switch , has the Funtion to Change the Head lights to LOW or HIGH Beam.
Check for proper funtion.
On left side of the Engine compartment In the Fuse block.
Check the FUSE # 13, 15amp. Replace if need.
The TURN signal work with the Same FUSE # 13. 15 amp.
Related with the Turn Signal switch.
Ok. The blower MOTOR.
Some times work And some times not.
Check the ground wire "BLACK" Below right side of Instrument Panel. If the ground is OK..
Turn the Ignition key to RUN position,
SET the A/C fan to MAX position or HIGH position.
When the Fan is set to High The system make a BY pass At the Blowert motor REsistor. and use a Blower motor Realy to give a High speed.
Using a TEST LIGHT,
Check if There a POWER 12v. at the Green/red Wire.
If you found Power . Check if there a Negative 12v. at the Black WIRE. If you found negative 12v.
Replace the BLOWER MOTOR..
For the Instrument Panel. I recomend Check the FUSE # 3
In the fuse box, Left Rear of the engine compartment.
If the fuse is ok. Check for Power 12v. if you found power
check all the grounds. But if NOT. I recomend Replace the Ignition switch. Because can be the Cause of the Electrical problem in your car.

OK.. I hope this help to try diagnostic your vehicle.
Thank you for use fixya.

SOURCE: oil gauge fluctuates back and forth. sometimes

You'll need to determine if the oil pressure is actually changing, or if the sending unit or gauge is lying to you. Be certain the oil level is up to normal, then check the actual oil pressure with a test gauge. If the pressure varies (drops) at engine idle, perhaps your pressure bypass is defective, or perhaps the oil pump is worn. Testing with a known good pressure gauge should lead you in the right direction.

SOURCE: How to fix 1999 lincoln TC heater/AC fan speed.

You have a problem with the resistors on your blower motor. 95% of AC/Heater blower motors are located under the glove box in the passanger foot well. When you remove the motor you should see a resistor plate. Resistors are not servicable and will need to be replaced. This is a relatively cheap part, that you can replace yourself if your handy, if not take it to your local tech.

SOURCE: Passenger window rolls down window but does not roll up

replace the switch. They have parts made of plastic pressing on the contacts softing these babies up making them useless in a few years

SOURCE: '01 e39 525i a/c blower motor intermittent fan

BMW blower fan stop after sometime then start up again by itself.