Turning on FAN causes Heating cartridge to go OFF. What could be the reason.

Turning on FAN causes Heating cartridge to go OFF.

What could be the reason. I am using RAMPS 1.4

Within the default programming of Merlin (I’ll assume you’re using Merlin firmware) there resides:

#define FAN_PIN 9

#define PS_ON_PIN 12
#define KILL_PIN -1

#define HEATER_0_PIN 10
#define HEATER_1_PIN 8

Now we know that the pins responsible for the fan & heaters are sequential. So as a minimum, check your Ramps’ connections for your thermistor, hot end & fan. Pull them off, inspect the connectors & pins, put them back on (no need to blow on them).

Hopefully that helps. If not: either your software is mal-configured; your connections are poor; or a component has failed on your Ramps. Check out http://reprap.org/wiki/RAMPS_1.4 for more information.

Thanks @Woody_Williams , I will check as per your suggestion.