Honda ACCORD HYBRID 2005 Service Manual page 1591

Stage 1. Uses both sides of the compressor for m a x i m u m cool d o w n . The electric m o t o r runs at highest RPM anytime
the evaporator temperature is above a predetermined threshold and then drops the RPM as the evaporator
temperature decreases.
Stage 2. The mechanically driven side is used w h e n a stable temperature is reached inside the vehicle. This is
determined by blower fan speed. If the fan speed is high, the electric compressor cannot maintain the evaporator
temperature.
Stage 3. Once the vehicles' interior temperature stabilizes, the electric compressor is used to maintain the interior
temperature. The PCM decides h o w fast to turn the electrical compressor based on all inputs. If the interior
temperature rises above the threshold value, the system switches to the mechanically driven compressor, and shuts
d o w n the electric compressor.
During idle stop, the compressor speed initially drops to a m a x i m u m of 1000 RPM to reduce under hood noise. The
speed will then s l o w l y increase w h e n additional cooling is called for. Blower fan speed also adjusts w i t h compressor
speed.
Auxiliary Electric Water Pump
A 12 V auxiliary electric water p u m p is used to circulate coolant to maintain heater performance during idle stop.
Auxiliary Electric Water Pump logic
The heater control module operates the p u m p , based on an idle stop signal f r o m the PCM. The p u m p maintains heater
temperature d u r i n g idle stop however using hot coolant f r o m the engine w i l l cool the engine. If the ECT temperature
drops below a predetermined setting the engine w i l l restart. There is also a temperature sensor located at the heater
core. It is used to monitor the auxiliary electric water p u m p operation. If the p u m p fails the core cools quickly
indicating a p u m p failure. In addition, the auxiliary electric water p u m p connector includes a second set of contacts to
establish continuity t h r o u g h the connector. If these contacts open, the heater control m o d u l e w i l l set a DTC.
To heater valve.
P E R M A N E N T DRIVE M A G N E T
(cont'd)
21-21