A G.C. only works if things are constant. Constant pressure to create constant flow. Oven temp must remain constant.........
The wires on the right come from the relays up in the top where our electronics are and go to the heaters inside and then wires carry the voltage to return.
The wires on the left are going to the thermistor's. One is control and one is overtemp. If we overtemp then it open up that relay which will not let 120 go down to the heaters.
After looking at the picture above, where does the air come in and then exit?
As long as we are not in overtemp or we have a bad thermistor bead then we will have 5 volts will come off T1 and land on relay 2 at point 3 and then exit it off 4 and then go to ground. With that voltage it closes the top side of the relay. Relay one is the control and voltage landing on 3 and out 4 will turn on and off as needed to open and close the top which lets the 120 go to the heaters. Notice that there are two wires coming off relay 2 and to the heaters and then it's one common wire from both of them to heater return. 

So from SSR up to relay 1 on 2 with closed to 1 and out to relay 2 on 2 and with closed to 1 and that carries 120 to both heaters and back together for a common return. 

If you ever have to change one of these out. Cut the wires in the oven from the old and then fish tape the new ones up. Otherwise you are screwed and will be trying to push up a hole that won't cooperate.........