Freezing your hard drive in an attempt to recover the data is commonly discussed on forums. Whilst it may help in many instances, it can also cause further problems in others. The principle is that when the user spins up the hard drive from an extremely cold temperature, they have a longer opportunity to extract the data before heat crashed the drive.

We also use a similar technique but without the freezer and this is why! A hard drive has a breather hole in the chassis.  This is to allow pressures to equalise both inside and out when the drive is spinning. Although this breather hole is only tiny and does have a filter, moisture can easily penetrate! Whilst it is true that if you can keep a failing hard drive cool, you may be able to run it for a longer period enabling you to retrieve valuable information before it crashes - once the drive has already failed, there is little that can be done by cooling the mechanics.  Indeed putting your hard drive in the freezer, risks moisture ingress.  Similarly, a sudden cooling may also cause any minute water particles inside the drive to condensate.  My suggestion would be to leave the freezer well alone!  Better to use a desktop fan on the drive whilst it is spinning!