MACS Service Reports - 2016 - OCT4

market with OE duplicates, the lower-cost aftermarketonly makers must do more. There's a little time to develop answers, but they have to be produced and they
have to fit without a lot of modification.
*with the integrated assembly, you have to replace two
heat exchangers (as on the Prius) when only one unit has
failed, unless you can make a repair, as by sealing a leak.
This obviously is more likely with something like the
dual radiator on the Prius, less likely where the failure is
on a condenser section. If it's plugged, no choice, but a
leak? Check with a shop that does heavy-duty radiators
- it probably can seal it. ■

High-performance cars with sloping noses have vertical space problems and may add a second radiator. Hybrids have packaging problems, which is why Prius has
done so much with integrating front-end heat exchangers.
So when it comes to replacing parts, you'll usually find
a front-end cooling module that is one of the following:
*Somewhat like a jigsaw puzzle, with parts having to
be a specific size and with specific bracketry - a lot fewer
of the adjustable brackets on semi-universal aftermarket
heat exchangers will fit in anymore. But the aftermarket
is seeing the challenge. And although the companies that
supply the OE manufacturers also are serving the after-

This term refers to the remote
control of the air conditioning
system on plug-in hybrid Prius
(PHV), and we are reasonably sure
that you'll also see systems on
competitors' cars that are similar
to what Toyota uses on its plug-in
Prius. That is, control by smartphone apps. They are different
from systems on plug-in hybrids
that only pre-heat or pre-cool the
passenger compartment when the
vehicle is plugged in. The Toyota
system, of course, operates on the
power from the high-voltage battery, and works only according to
an algorithm. The remote A/C, of
course, does not require the vehicle to be plugged in or the engine
to run (in fact, the system is independent of the engine, using the
electric compressor, a scroll type).
At some point you'll face the
customer complaint that the system doesn't work on smartphone
app "remote," but functions normally in vehicle operation. The remote system algorithm relies on a
number of inputs (FIG. 8), and although we're not going to provide
a complete system operation and
diagnostic routine in this issue, it's
a good time to introduce what will
be an important subject for HVAC
specialists to understand.
To activate the Prius system, the
following conditions must hold: 1)
vehicle power off. 2) doors closed
and locked,
and powertrain
compartment hood closed. 3)
transmission in Park. 4) adequate

October 2016

techinfo.toyota.com

"REMOTE AIR CONDITIONING SYSTEM"

Figure 8: System diagram for Prius plug-in hybrid's remote air conditioning. Note the DCM (telematics
transceiver), which is on the CAN V1 bus, so it communicates with the A/C amplifier and via a smartphone or smart keyfob, with the remote A/C.

MACS Service Reports

http://www.techinfo.toyota.com

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