Owner Manual

11.1.2 Limit Switches
The Dallas board has independent inputs for low limit and high limit switches.
The auto-reset high limit switch is designed to trip at 550 psi and will shut the compressor down
for 5 minutes after the switch resets. A RED light will blink on the LED board labeled “HIGH
PRESSURE LIMIT” while the limit is tripped and will turn solid RED when the switch has reset. If
the switch trips 3 times in any 30 minute period, the board will lock the compressor out. When
this occurs, a RED light will blink, indicating the unit is in lockout status. Power must be cycled
to reset the lockout but SHOULD ONLY BE DONE AFTER THE CAUSE OF THE TRIP HAS
BEEN DETERMINED AND CORRECTED!! FAILURE TO DO THIS CAN DAMAGE THE UNIT
AND VOID THE WARRANTY!!
The auto-reset low limit switch is designed to trip at 75 psi and will shut the compressor down
for 5 minutes after the switch resets. A RED light labeled “LOW PRESSURE LIMIT” will blink on
the LED board indicating the switch has been tripped and will turn solid RED when the switch
has reset. If the switch trips 3 times in any 30 minute period, the board will lock the compressor
out. Power must be cycled to reset the lockout but SHOULD ONLY BE DONE AFTER THE
CAUSE OF THE TRIP HAS BEEN DETERMINED AND CORRECTED!! FAILURE TO DO
THIS CAN DAMAGE THE UNIT AND VOID THE WARRANTY!!
11.1.3 Freeze Protection (lack of water flow)
The Freeze stat helps protect the liquid to refrigerant heat exchanger from freezing internally.
Freeze protection is accomplished by measuring the refrigerant temperature exiting the water
coil in the heating mode. If this temperature drops below the freeze set point, a RED light
labeled “FREEZE PROTECTION” will illuminate and the unit will lock out until manually reset.
RESETTING SHOULD ONLY BE DONE AFTER THE CAUSE OF THE TRIP HAS BEEN
DETERMINED AND CORRECTED!! FAILURE TO DO THIS CAN DAMAGE THE UNIT AND
VOID THE WARRANTY!!
On closed loop units WITH ADEQUATE ANTIFREEZE, the tab labeled “ANTIFREEZE” will be
broken off, lowering the system freeze setpoint to 20 degrees. Use a small pair of needle nose
pliers to break the tab (see image on page 13 for location).
IMPORTANT!!! Once the tab has been broken, the system will always be set to 20 ❄
degree protection and can not be reversed!! Removal of the tab on open loop systems or
closed loop systems without minimal freeze protection will VOID all warranty on system!!
❄
On open loop units, the tab MUST remain in place, giving the system a 38 degree freeze
setpoint.
11.1.4 Condensate overflow switch
Page 22