Pilot on, gas fires up, no fan comes on.

https://manualzz.com/doc/47948376/bonaire-vulcan-quasar-manual-wall-furnace-owner-manual

The igniter may be bad and needs replacing.

Make sure the local gas valve is on some heaters take the pilot gas before main valve.

Has the Gas Control Knob been turned from the Pilot position to the ON position? If not, it won't light the burners.

What do you mean by the pilot light is on but won't light. Do you mean that there is gasbut won't light. If so the spark may not be hitting the pilot properly or it may not be getting enough gas. If lighting but continuing to spark the sensor may need cleaning. This can be cleaned with steel wool (not sand paper), probably will need to disassemble the pilot asembly The pilot may also be dirty reducing gas flow. If this is the case dis-assembly will be needed and the pilot cleaned.

Simply clean out the jet tube with a fine wire, the sound you hear is the gas blowing by the irregular edges, and swirling and not mixing and producing sound waves, (Bit like a flute) So, you need to clean the tube right out, and smooth off the end again, & sorta "Countersink", Flame the end too, at the end.use a very fine needle file, and make it look like new, that will sort your problem out. Then adjust so you have a good gas flow. Also check out it isn't blocked too.

Have a gasfitter bypass the clock. The clock is the source of the problem. You will then have a manually operated heater.

Hi the problem you have is your heater is cutting out due to the over temp switch getting to hot the reason for this is that your fan is not working thus not enough air flow is getting through the heat exchanger to keep it cool
your heater is designed to not exceed a certain temprature so as not to become a fire risk
to solve your problem you will need to replace your fan
this will solves your problem

Replace the fan thermal switch located at the top of the heat exchanger. Unplug the power first as the switch is 240V.
Available from any plumbing trade shops e.g. Reece & Tradelink

Look for dust and lint. Look for them in places where gas should be freely flowing. I had a similar problem with an Empire Corcho wall-mounted propane ceramic catalyst heater. First it was the pilot light, then the #2 ceramic mantle. After horsing around with the gas lines and pressure regulators and trying to re-aim the pilot, it all turned out to be dust and lint in the gas passages. A little dust bunny in the brass pilot tube gave me a pilot light the shape and color of a banana. One puff of compressed air, and I got back my razor-sharp pilot. And some dust in the chimney of the #2 burner kept it burning blue/yellow and blistering paint off the upper surfaces of the heater. A bit of cleaning with a shop-vac put that right. "Passive" heaters are very much prone to this sort of problem because they rely on convection currents (i.e. LOW velocity) to get the job done. Convection currents are notorious dust collectors, as in COBWEB CITY.