Yes, to test the system by simulating a sensor call for heat, connect a short jumper wire between terminal block terminals 25 (sensor signal) and 24 (sensor ground). Now the Heat LED should turn on within 10 seconds and the control relay should close. If the Heat LED does not turn on with terminals 24 and 25 connected, then the EUR–5A is defective. The snow and heat indicators will come on and relay or contactor will be pulled in. If the Heat LED does turn on there is a problem with your sensors or sensor wiring.