5:4
LED Alarm Indicator - Diagnostic Diode
A 12v LED may be installed across the "+" and "D" (or “D/I”) terminals of the controller to indicate a
failure condition. On the Coastal MK3 one is installed on the front panel and labeled “Fault”. On the
Merlin II
a red LED is installed on the face of the PCB and labeled “Alarm”. Under a fault condition, the
compressor will be stopped and an attempted restart will be made approximately every 45 -90 seconds.
Under this condition the LED will blink between 1 and five times every 5 seconds, as follows:
1 Blink:
Supply voltage low, below 10.4v on a 12v system, 22.8v on a 24v system
2 Blinks: Excessive load on fan terminals, above 0.7 amps
3 Blinks: Compressor non-start (Common occurrence, and normal when compressor
stopped and started again too quickly)
4 Blinks: Compressor speed below 1900 RPM
5 Blinks: Controller electronics temp too high. Re-sets on cool-down
Note 1
After power is applied to the controller there may be a delay of up to 30 seconds before the compressor
starts.
Note 2
If initial power is applied that is above the low-voltage threshold but below the cut-in voltage value
(see 5:3 (1), digital displays will be lit, but the compressor will not start and there will be no
fault indication on the LED. System will start when voltage is increased above the cut-in value.
Note 3
The electronic controller, although designed for harsh and marine applications, can be damaged by
either direct or incidental contact with water and by water flowing down wires attached to the
terminals. When attaching wires to the terminals on the controller, make sure that all wires approach
from below the terminal, and endeavor to mount the compressor and controller combination in a
location that is clear of existing and potential water leaks.
Note 4
The electronic controller is secured to the compressor by a single screw and a push-on three-pin plug.
The hole in the controller housing is larger than the screw head, and it is permissible to lever the casing
over the screw for easier removal if access is limited.
