Thermocouple

If your multimeter is designed to display temperature when connected to a thermocouple, it will incorporate circuitry to perform cold junction compensation (click to read about it in wikipedia).

Measuring the thermocouple voltage with a multimeter and using a lookup table to find the temperature will not give an accurate result.

Thank you john

Depending on the CJ temperature of the meter, you may be introducing errors by using a meter in temp mode.

Make sure the meter CJ temp has equalised with the ambient temp before taking a reading.

The most accurate method is to only measure mV, and measure the CJ temp accurately (hi resolution laboratory glass thermometer, or RTD in a CJ box), then use your tables.

You check millivolts from Thermocouple and than check on table where is temperature against millivolts

if both mv against chart and temperature displaying on multimeter r same than thermocouple giving prob. if differ in reading on multimeter than change multimeter, by ranjha