Spa: 1993? Great lakes spa 5 person
230v single 2 stage pump and blower
control: brett aqualine EM-100
Air push button
1 main pump 230v 2 speed
thermostate: knob on topside control, pushbuttons on topside control, knob on side of heater / controller
heater: 2" Stainless Flow Thru, 15" long

My heater light on the controler wont come on. The light on the top says the heater is on and when i turn the temp sensor( on top of spa) down and up the heater clicks and kind of stutters if i hold it at the threshhold of on and off. The pump is running fine but the heater is not working. Thanks
Nick

check your pressure/flow switch for continuity when the topside calls for heat. No continuity, no power will get to the heater circuit.