Often this is just dirty condenser coils.
See the link below #18
http://www.applianceaid.com/refrigerator.html

Also check that the condenser fan is running.

The way I clean mine is to remove the kick plate and the lower rear cover.
I then roll it over to the open kitchen door and blow it out with my compressor, most of the dust ends up outside. Also a leaf blower works.
This may not be possible for you inwhich cae a vacuum and a brush works.
They do make special long brushes just for this job.
Also clean the fan and it's blades.

Some units do have a similar set up but there is usually an energy saver or econo switch on the control pane to shur this off.