MCC EM-1 Manual page 40

Table 3-5 TROUBLESHOOTING ALARM CODES (TOTAL CONTROL) Cont::
AL 47 Not Used
AL 48 Heating Valve
malfunction
If the controller calls for cooling (green led is on), the condenser and evaporator fans are running, but
the compressor is OFF without any alarm code, this indicates one of the following has occurred:
1. The freeze stat is open. The compressor is disabled when the freeze stat is open and will be enabled when the
freeze stat is closed.
2. The low pressure switch, also present in the evaporator (GEN 5 units) which is in series with the freeze stat is
open.
3. The compressor is disabled by minimum off time. When the compressor is turned OFF by temperature con­
trol, freeze stat, low or high pressure switches, it will remain OFF for a minute (60 seconds) before it is re-en­
ergized. This protects the compressor clutch from short cycling.
© 2012 Mobile Climate Control
Malfunction is detected on
the HV output.
NOTE
3--7
T-299 Rev. 08/2012