The pointer points to the beginning of the scale.

The "+" and "-" poles of the thermocouple are connected incorrectly;

Thermocouple or wire disconnection (moving coil instrument);

The thermocouple and instrument models do not match.

Replace the "+" and "-" poles. Repair the thermocouple and connect the wires. Replace the thermoelectric fan or instrument.

The pointer points to the upper limit of the scale.

Thermocouple or loop wire disconnected (electronic potentiometer).

There is DC interference signal entering.

The thermocouple and instrument models do not match.

Repair the thermocouple and connect the wires. Eliminate DC interference. Replace thermocouple or meter.

The pointer does not move at zero.

The measurement line is short-circuited. The thermocouple circuit is broken (moving coil instrument). Loose terminals (moving coil instrument).

Check, fix. Check, fix. Tighten.

The pointer stops moving.

Thermocouple or circuit break (electronic potentiometer).

The terminals are loose or have poor contact (electronic potentiometer).

Check, fix. Tighten.

The pointer swings, sometimes not, sometimes high, sometimes low.

Poor contact between connecting parts.

The insulation of the thermocouple measurement line is damaged, causing intermittent short circuit or grounding.

The hot electrode will break but not break.

External interference (AC leakage, electromagnetic field induction, etc.).

The thermocouple is not installed securely or vibrates externally.

Wipe the connections clean and retighten them.

Find the fault point and repair the insulation.

Repair hot electrode or update.

Find out the source of interference and shield it.

Tighten the thermocouple to eliminate vibration,

Or take vibration reduction measures.

Indicates low temperature

The thermocouple does not match the instrument.

The compensation wire does not match the thermocouple.

The polarity of the compensation wire and the thermocouple are reversed.

The hot electrode deteriorated and the measuring end was severely corroded. The insulation is damaged, causing leakage between hot electrodes or wires.

The thermocouple is installed in an improper position or inserted into an insufficient depth (the measured temperature is higher than the ambient temperature).

Replace thermocouple or meter.

Replace the compensation wire.

Reconnect.

Reprocess or replace the thermode. Repair or replace insulation.

Reinstall as required.