Trans Air EC3.0 Service Manual

Service Manual For
Trans/Air EC3.0 Electronic Climate Control System

Specification

Operating Voltage:

9~16 VDC

Current capacity:

Evaporator: 40 amp
Condenser: 40 amp
Compressor: 10 amp
Tie-in Condenser: 40 amp
Tie-in Compressor: 10 amp
Heat Relay: 10 amp

Setpoint range:

60ºF ~ 90ºF

Component:

EC3.0 system consist of two major components: driver control switches and relay board. A
communication cable connects the switches to the board.

Switches

EC3.0 control switches: Mode switch (701426), Thermostat (701425).

ON/OF & MODE SELECT
A/C-DEFOG-HEAT-OFF

DEFOG
HEAT

A/C

FAN SPEED INDICATOR

FAN SPEED SELECT

AUTO-L-M-H-OFF

Figure 1 Control Switches

DISPLAY

SET POINT
ADJUST

Relay Board

The layout of an EC3.0 relay board is shown below. It has five relays, one 12 position
terminal block, three 10 amp fuses, two connectors and seven LED indicators. The function
of each component are listed in table below

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Figure 2 Relay Board Layout

Table 1 Relay Configuration

RELAY FUNCTION Currant rating
COMPR. Compressor clutch relay 10 amp
TIE-IN COMPR OEM tie-in compressor clutch relay 10 amp
HEAT Heat valve control relay 10 amp
TIE-IN COND. Tie-in condenser fan control relay 40 amp
COND. Condenser fan control relay 40 amp

Table 2 Fuse List

Fuse Description Rating
F1 Comp. Clutch fuse 10 amp
F2 Tie-in Comp. clutch fuse 10 amp
F3 Heat relay output fuse 10 amp

Table 3 Terminal Configuration

TERMINAL FUNCTION
1 Compressor clutch output
2 Tie-in compressor clutch output
3 Heat control relay output (optional)
4 Dash signal input
5 Ignition power input
6 Tie-in condenser power input
7 Tie-in compressor power output
8 Condenser power input
9 Condenser power output

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