6
53-22130A100
131 EISENHOWER LANE NORTH
LOMBARD, ILLINOIS 60148-5413
630-268-0010 / 1-800-251-2408
ELECTRONIC CLIMATE CONTROL
INTELLITEC
The SHORT INDICATOR operates in the OFF and TEST modes of the TEST SWITCH.
The Control Module also includes protection circuitry to eliminate the possibility of “short-cycling” the A/C
compressors. Short-cycling causes undue stress on the compressor motor when refrigerant pressures are not
allowed to stabilized prior to restarting the compressor. A two minute timer is incorporated in each of the
control systems for the front and rear A/C compressors. The timer is started each time one of three conditions
is encountered: 1) If the Control Module shuts down the associated A/C compressor during a the shedding
sequence, or if the ambient temperature has reached the set point. 2) If the 120 VAC line current sensed by the
Current Sensor goes below 1 Amp. This will occur during an interruption of power, if the generator is not
running, or if the shore power cord is not plugged in. 3) If +12 VDC power is not applied to the Control Module.
The Control Module does not allow the compressor to be re-energized until the two minute period has elapsed.
If during this period, the coach requires cooling or if the unit is recovering from load shedding, the Control
Module will signal the ECC Thermostat to alternately flash the ON and SHED indicators on the control panel
until the period has elapsed. After the two minute period has elapsed the system will return to normal
operation.
An important feature included in the Control Module circuitry is the Automatic Load Shedding function. This
circuitry measures the total current being drawn by all of the 120 VAC operated equipment in the coach being
fed through the main panel. The Current Sensor is mounted in the main panel and supplies an input signal to
the Control Module. When enough 120 volt appliances are operated so that the current exceeds 30 Amps for
more than approximately 3 seconds, the Control Module begins to shed (shut off) the A/C compressors and
fans to bring the current back below the 30 Amp limit. This prevents nuisance tripping of the main 30 Amp
breaker. The shedding sequence occurs in the following order:
1. Rear A/C compressor (if running)
2. Front A/C compressor (if running)
3. Rear A/C fan (if running)
4. Front A/C fan
When the Control Module sheds any of the loads, it returns a signal to the ECC Thermostat to light the
corresponding front or rear SHED indicator. Based on the shedding sequence, the rear SHED light will always
be the first to light. If enough appliances are operated to generate a load current of 30 Amps, the Control
Module will proceed through the entire shedding sequence and essentially shut down both A/C compressors
and fans. (It is important to note that if the Control Module has shed all four loads and the line current continues
to exceed the 30 Amp limit, it is likely that the 30 Amp line breaker will open.)
ALTERNATING OPERATION:
If the total current being drawn is such that only one A/C can operate, and the ECC Thermostat continues to
demand that both A/C compressors operate, the Control Module will alternate operation of the front and rear
A/C compressors every 30 minutes. When the line current is low enough to allow operation of both air
conditioners, the Control Module will restore their operation in a reverse order to the shedding sequence. The
front or rear SHED indicators on the ECC Thermostat will remain lit until the corresponding A/C compressor
and fan are restored to normal operation.
