The MMTS measures the current temperature over a range from –55o to +125o F and compares it to the highest and lowest values stored in the memory of a microcomputer. If the current temperature exceeds the previous highest or lowest reading, then it becomes the newest maximum or minimum temperature.
The current temperature (85.4) is displayed if no buttons are pressed.
Depress the "MAX" button to display the maximum temperature that occurred since the MMTS was last reset. Depress the "MIN" button to do the same for the minimum temperature.
Simultaneously press the "RESET" and "MAX" buttons to reset the stored maximum temperature. Do the same with the "RESET" and "MIN" buttons to reset the minimum temperature.
Record the maximum, minimum, and current temperatures on WS Form B-91. Record to the nearest whole degree, even though the readings are displayed to the nearest tenth degree. If the last digit is a 5 (e.g., 85.4), round the temperature upward to the next higher whole degree (i.e., 86).
"HELP" and Blinking Displays
If the "HELP" message appears on the display, press the "RESET" button to clear it and to show the current temperature. "HELP" indicates an interruption to the A.C. line voltage has occurred. The microcomputer enters a "power down" condition in which the internal backup battery is used to preserve the maximum and minimum values stored in memory. These values are stored up to two hours without power. However, no updating of new maximum and minimum temperatures occurs during or after the power interruption until the "RESET" button has been pressed.
Blinking of the tenths (right-most) digit on the display indicates that the internal backup battery is charging. If the blinking persists and is not caused by power outages, the battery is probably defective, and the NWS representative should be informed.
Record the temperature data on the day read not on the day maximum (and occasionally the minimum) temperature occurred.