default_cooldown change shouldnt force new resource - https://github.com/hashicorp/terraform/issues/2509 - credit to

@phinze and @mzupan for https://github.com/hashicorp/terraform/pull/2147

builtin/providers/aws/resource_aws_autoscaling_group.go

@@ -59,7 +59,6 @@ func resourceAwsAutoscalingGroup() *schema.Resource {
 				Type:     schema.TypeInt,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
 			},
 
 			"force_delete": &schema.Schema{
@@ -219,6 +218,10 @@ func resourceAwsAutoscalingGroupUpdate(d *schema.ResourceData, meta interface{})
 		AutoScalingGroupName: aws.String(d.Id()),
 	}
 
+	if d.HasChange("default_cooldown") {
+		opts.DefaultCooldown = aws.Long(int64(d.Get("default_cooldown").(int)))
+	}
+
 	if d.HasChange("desired_capacity") {
 		opts.DesiredCapacity = aws.Long(int64(d.Get("desired_capacity").(int)))
 	}