Another reason of such blockage is the presence of air in the gas line.
Propane wall mount heater shuts of after 30 sec.
Also there may be a pilot adjustment valve on your gas valve.
If so replace the entire valve.
Step 2 close the empty propane tank if it is small enough to remove by turning the handle counterclockwise as far as it will go.
Gas valve are allowed 30seconds to fall out.
This might happen due to corrosion to the orifice and you don t have any choice apart from replacing it with a new one.
If heater keeps shutting off have it serviced.
Turn the control from the on position all the way over to the off position.
How to troubleshoot gas wall heaters.
The third reason of why your propane heater keeps shutting off can be a blocked up gas valve orifice.
On wall mount heaters it is usually located on the front of the heater near the floor.
If heater shuts off do not relight until you have provided fresh outside air.
Gas wall heaters whether vented or unvented can supply enough heat to warm a small or medium sized room and they can operate with propane or natural gas.
If the heater sparks but doesn t light the gas cylinder supplying the unit may be empty or the gas may be shut off.
There could a fault in the gas valve s main burner solenoid causing it to draw excessive power and starving the pilot flame solenoid.