I cannot find any info on the given model number.
Are you sure it is not a HTS18BB.
Also there should be additional digits at the end of the model number.

They usually do not run all the time.

Even more important is to check that the compressor and it's fan are not running all the time. If they are then it will cost a small fortune in electricity.
You can usually hear if the compressor is on and you should be able to feel it vibrating.
Since this is a GE unit getting tech info on it is nearly impossible but on most older units the fans and the compressor are all on one circuit.

Check your temperatures. The freezer should be about 0 to 5 degrees F and the fresh food should be around 40 degrees F.

If the compressor is running all the time then possible causes are:
1. dirty condenser/compressor coils.
2. the condenser fan is not running when the compressor is on.
3. doors seals are not sealing correctly
4. a defrost problem. Remove the cover in the freezer so you can inspect the evaporator coils. if they are iced/frosted over to the point where the fan cannot pull air through them, then you have a defrost problem.
5. a sealed system problem. Again pull the cover and inspect the evaporator coils. But this time the symptom is that there is just frost in one area on the coils (usually where the freon enters the coils).