| Depending upon the model of alarm, there could be a few "upgrades" available.
The early evo + alarms suffered with water entering through the siren. There is a new cover available with a sealed unit fitted.
The later alarms have a potted circuit board that is very reliable. These are usually retro fitted under warranty circumstances. If the alarm is still warranted, it may be worth a call to your installer. | 
Threaded Mode