Blower Speed Compensation
NCHA0062S05
Sunload
NCHA0062S0501
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low
speed. The low speed will vary depending on the sunload. During conditions of high sunload, the blower low
speed is “normal” low speed (approx. 6V). During low or no sunload conditions, the low speed will drop to “low”
low speed (approx. 5V).
Ambient
NCHA0062S0502
When the ambient temperature is in the “moderate” range [10 - 15°C (50 - 59°F)], the computed blower volt-
age will be compensated (reduced) by up to 3.5V (depending on the blower speed). In the “extreme” ambi-
ent ranges [below 0°C (32°F) and above 20°C (68°F)] the computed objective blower voltage is not compen-
sated at all. In the ambient temperature ranges between “moderate” and “extreme” [0 - 10°C (32 - 50°F) and
15 - 20°C (59 - 68°F)], the amount of compensation (for a given blower speed) varies depending on the ambi-
ent temperature.
Fan Speed Control Specification
NCHA0062S06
RHA195H
RHA054H
COMPONENT DESCRIPTION
NCHA0063
Fan Control Amplifier
NCHA0063S01
The fan control amplifier is located on the cooling unit. The fan
control amp. receives a gate voltage from the auto amp. to step-
lessly maintain the blower fan motor voltage in the 5 to 12 volt
range (approx.).
RHA467G
DIAGNOSTIC PROCEDURE
NCHA0064
SYMPTOM: Blower motor operation is malfunctioning under
Starting Fan Speed Control.
GI
MA
EM
LC
EC
FE
CL
MT
AT
AX
SU
BR
ST
RS
BT
SC
EL
IDX
TROUBLE DIAGNOSES
AUTO
Blower Motor (Cont’d)
HA-67