Yes, mine is located there too:
The furnace likely will run this process:
With the thermostat turned on the heater will switch the blower on and run for several seconds, then it will try to light itself from the propane tank, you should be able to hear the gas valve open, and then several clicks from the electric starter.
You appliance will have a shutoff valve at the lower right front corner. If the valve has been on all this time then with your propane tanks on it will likely start.
If the blower keeps running it is likely running. You can go outside and checkout the temperature of the exhaust. The rule is to have nothing, including your door in front of the exhaust.
Now I can't tell you about the condition of your unit. Are there cracks in the heat exchanger for example. If so then the unit is not safe and is past a usable state and needs to be replaced. You could try a gas detector to determine if you can find a gas leak, which could either be propane or combustion products. Unfortunately either leak show presence differently. Propane near the floor and CO near the ceiling.
Or you can remove the five or seven outside screw and then from the inside take the front cover off. You will find two wood screws holding the heater to the floor. Then spin off the vents, close the gas valve (front right corner), disconnect the gas line and the unit will come out. You could then put the furnace on your work bench and inspect the unit. Taking the cabinet off isn't that much more work, which will improve you inspection. When I did this on my 1986 unit I found the unit was rusted out. Once again don't bother to try and have the metal repaired.