- Condition: The dryer has detected the temperature of the air exiting the outside of the heating chamber has exceeded 210 degrees.
- Alarm Action Taken: SHUT DOWN
- Component: Auto Reset Linear Limit
- Location: Inside a junction box mounted on the outside of the dryer at the lowest catwalk of the heat chamber of the dryer. There are normally two limits in each junction box, one that wraps around the right side and the other the left side. Some units have the capillary inserted inside protective copper tubes that are mounted horizontally around the circumference of the dryer with some type of “P-clips”.
Tools Required for Service:
- Voltage/continuity meter
- Small standard blade or Philips screwdriver (to open cover)
Tech tip: (115 vac circuit or completes a neutral circuit) (Resets automatically when cooled down)
A linear Limit is a normally closed contact capillary thermostat device that has a gas inside the capillary that expands when heated and opens up the contacts inside the limit when it detects an air temperature of 210 degrees. It is normally wrapped around the circumference of the dryer in multiple locations to monitor the air of the heating chamber as it exits the dryer.
The two limits are wired in series so a continuity meter is required to detect which of the two is the faulty unit.
(Use caution entering the dryer!! The linear limit thermostat indicates a high temperature condition unless faulty!)
Potential causes of this alarm condition:
- Over drying the commodity causing excess kernel temperature and excess heat exiting the heating chamber of the dryer
- A column of the dryer has plugged/stalled and is not flowing causing the grain to be over dried
- The dryer is not staying full allowing air to escape from the heating chamber
- Faulty linear limit
- A fire in the heating chamber!