Check High Temperature Thermostat
refrigeration
Description
With the Main Power switch out of OFF, the EVHTS circuit is open, and the unit alarms with no heat allowed.
Activation Conditions
With the Main Power switch toggled out of the OFF position, the EVHTS circuit is open.
Unit Behavior
Engine and Electric Operation: Alarm and no heat allowed.
Reset Conditions
Auto Reset when the EVHTS circuit is okay for 15 minutes, or alarm may be manually reset via keypad or by turning the unit off, then back on again.
Corrective Actions
1. Check Evaporator Area for High Temperature - Check Evaporator temperature using a test thermometer. EVHTS opens when the temperature of the evaporator becomes very high (Refer to Section 2.9). (for example, if the heaters are on when the fan is not running.) If the temperature of the evaporator section is very warm (hot), it will have to cool down before the EVHTS closes. 2. Check High Temperature Thermostat (EVHTS) - Inspect thermostat and connector. (See wiring schematic Section 10.2) No damage to thermostat. No damage or corrosion in connector. 3. Check High Temperature Contacts a. Contacts must be closed when temperature is normal. Unplug EVHTS and check for continuity. Must be 0 (zero) Ohms. Cannot be opened (infinite ohms) or shorted to ground. If EVHTS is open below temperature, (Refer to Section 2.9) replace EVHTS. b. Check ground at A2 on both 1HTCON1 and 1HTCON2. If ground not good, check connectors and wiring between terminals for damage, moisture or corrosion. c. Check for continuity from CCB-2 to 1HTCON1-A1 and CCB-20 (feedback). If the circuit is open, inspect all connections for damage, moisture, or corrosion.