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© 2012 Mobile Climate Control T-299 Rev. 08/2012
If low speed is selected, the microprocessor will
provide power from terminal EFM+ to energize the
low speed relay (LSR). Energizing LSR closes it's
normally open contacts to provide power from the
battery circuit b reaker through TB-8 to the low
speed resistor connection. It may be noted that the
high speed relay (HSR) is also energized at t h is time.
However, power is not available to the contacts of
this relay so no action will result.
If medium speed is selected, t h e microprocessor will
provide power from terminal BPV to energize the
medium speed relay (MSR). Energizing MSR closes
it's normally open contacts to provide power from
the battery circuit breaker through TB-5 to the
medium speed resistor connection. It may be noted
that power is also supplied to the high speed relay
(HSR) at this t ime. However, the relay coil is no t
energized so no action will result.
If high speed is selected, t h e m icropro cessor will
provide power from terminal EFM+ and BPV to
energize the low speed relay (LSR), medium speed
relay (MSR and high speed relay ( HSR). Energizing
allthreerelays closes contacts to provide the required
path from the battery circuit breaker through MSR,
TB-5, HSR and TB-4 to the high speed resistor
connection. Although all of the resistor connections
are actually powered, powering of the high speed
connection will bring the motors to high speed
operation.
If at any time during operation the circuit from
microprocessor t erminal BPT+ back to terminal
BPT- is opened by the freeze-up thermostat or low
pressure switch (LP - optional location) the
compressor clutch will be de-energized. Once the
circuit is re-established, the clutch will be
re-energized after a one minute delay.
When th e system is installed as a tie-in system, power
is supplied by the vehicle controls to the
microprocessor ignition terminal (NEIM) when
operation of the compressor is required by the
in-dash defroster. With power to the NEIM
terminal, the compressor clutch is energized.
On multiple compressor or multiple condenser
systems, operation is similar to the preceding
description except th e second comp ressor is
controlled from microprocessor terminal HP2+.
Refer to Figure 5-8 for typical schematic diagram.
2.8.5 Heat Option
When heat option is incorporated with the Total
Control system, the heater valve will be controlled by
the HGS2 terminal on the microprocessor.
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