Only issue MAXTEMP when heating

Marlin/temperature.cpp

@@ -1809,7 +1809,7 @@ void Temperature::isr() {
 
     for (uint8_t e = 0; e < COUNT(temp_dir); e++) {
       const int tdir = temp_dir[e], rawtemp = current_temperature_raw[e] * tdir;
-      if (rawtemp > maxttemp_raw[e] * tdir) max_temp_error(e);
+      if (rawtemp > maxttemp_raw[e] * tdir && target_temperature[e] > 0.0f) max_temp_error(e);
       if (rawtemp < minttemp_raw[e] * tdir && !is_preheating(e) && target_temperature[e] > 0.0f) {
         #ifdef MAX_CONSECUTIVE_LOW_TEMPERATURE_ERROR_ALLOWED
           if (++consecutive_low_temperature_error[e] >= MAX_CONSECUTIVE_LOW_TEMPERATURE_ERROR_ALLOWED)
@@ -1828,7 +1828,7 @@ void Temperature::isr() {
       #else
         #define GEBED >=
       #endif
-      if (current_temperature_bed_raw GEBED bed_maxttemp_raw) max_temp_error(-1);
+      if (current_temperature_bed_raw GEBED bed_maxttemp_raw && target_temperature_bed > 0.0f) max_temp_error(-1);
       if (bed_minttemp_raw GEBED current_temperature_bed_raw && target_temperature_bed > 0.0f) min_temp_error(-1);
     #endif