"maintain proper temperature" is correct and usable in written English.
You can use it when talking about ways to ensure something is kept within an acceptable (and safe) temperature range. For example: "It is important to maintain proper temperature when storing food in a refrigerator."
Often supermarkets do not maintain proper temperature in refrigerated cases for meat, poultry and produce.
The effect of wall cooling at low throughputs is to require changes in feed ratios order to maintain proper temperature ranges in dry ash and slagging reactors, and to keep the combustion zone low in the dry-ash Lurgi.
Not only must caretakers maintain proper temperature and humidity, but every so often they must regenerate, plant, and harvest the seed to keep it viable.
While LED efficiency is increasing, the energy it takes to simulate sunlight and maintain proper temperatures is huge.
The company's owner, Roger Thomas, said the company had repaired a thermostat that caused a dehydrator used to maintain proper temperatures to malfunction.
It is very important to maintain proper temperatures to secure the health of our turtles.
Maintaining proper temperature and humidity is important for retarding the growth of microbes.
The apparatus is designed to reduce uncertainty for high pressure measurements while maintaining proper temperature control in the sample.
Keep food safe by maintaining proper temperatures.
"Here, it's moose mittens". On a visit last week, it was minus 7 degrees Fahrenheit with a vigorous west wind, conditions that challenged the operation of cooling systems (making it hard to maintain proper engine temperature) as well as the technicians (it felt like 36 degrees below zero).
The creatures go into a kind of trance as they release their eggs then use their hind flippers to cover them with sand, hiding them from predators and ensuring the eggs remain moist and maintain proper incubation temperature.
