Simply pre-load the ELSE condition into the variable before entering the IF loop...
Code:
module_rel_out=0
if level<=high_level then
	if thermiko1=0 then
		if thermistor1=0 then
			if auto1=0 then
				if onboard_an2<=pres_limit then
					if pump=0 then module_rel_out=1
					endif
				endif
			endif
		endif
	endif