Second extruder question

I have an I3 rework running on ramps 1.4/mega 2560. I am running Marlin 1.0.2.
I intend to use the 2nd extruder thermistor to control a heater in my enclosure, which is currently running off an external controller.
As I have a heated bed I intended to use the D9 output to run the heater. My print fan was running off D9 so I have added a fan extender to the d4 pins, and changed fan_pin in pins.h to 4 from 9, the fan works just fine.

I have changed the number of extruders to 2 in configuration.h and set motherboard 34 (extruder,extruder,bed) but I ran into a problem compiling "unable to find a register to spill in class 'POINTER_REGS'" I did find the solution online which was to enable the thermal runaway protection for extruder, which then threw a different error until I enable it for heat bed also. Having done that I have managed to write the firmware to the arduino.

However my second extruder now reports 483 Deg C connected or 500 Deg C if I disconnect it. Even stranger the temperature reading goes down if I warm the thermistor in my hand.
This thermistor reports around 135 Kohm resistance at 18 deg C.
I am using the same thermistor as I have used on my heatbed (I bought a pack of 5) which were supposed to be 3950 thermistors (type 11 in Marlin).

I have obviously missed something obvious does anyone know what it is? I have attached my config, pins and thermistortables.

The other question was that since my enclosure heater is a hairdryer I intended to switch it by bang bang control via a mechanical power relay, as a PWM signal via an SSR would not work for a hairdryer with a fan in it, correct? Can I enable PWM for E0 and bang bang for e1?

Edited 3 time(s). Last edit at 01/13/2016 07:33PM by DjDemonD.

There is an odd logic to this in that when I short the extruder 2 thermistor pins on the ramps I get a reading on the lcd of 0 deg c. When these pins are open (no thermisotr attached) it reads 500 deg C and with the thermistor atteched 483 deg C. My ambient air temperature (and the reading on my other two thermistors) is 17 deg C. So it is of a fashion working, but the output seems to be inverted.

SOLVED - had to define it as temp_sensor_1 not temp_sensor_2.
and ensure redundant temp sensor 1 was commented out

But anyone got any thoughts on best way to switch a hairdryer on/off using e1 thermistor and d9 output on ramps and marlin 1.0.2?

Edited 2 time(s). Last edit at 01/14/2016 06:12PM by DjDemonD.

Seems that selecting slow_pwm in configuration.h will allow more reasonable control of the hairdryer. It does make the hotend a little less precise in heating up. It's a shame the settings for all extruders are the same, it would be very useful if each extruder could be configured independantly.