Mazda MX-3 silhouetteMX-3

HEATER CONTROL UNIT - Inspection (Fan switch, A/C switch, REC switch, FRESH switch)

G-46prose procedure

A/C switch inspection differs for Logic type vs Wire type heater control units.

Inspection

Fan switch

  1. 1
    Check for continuity between the terminals of the fan switch.
    Fan switch connector terminal layout. Top row terminals H, F, D; bottom row terminals G, F, B (positions identified at the connector pins).
  2. 2
    If not as specified, replace the fan switch. (Refer to page G-44 or G-45.)

Fan switch terminal continuity (O—O: Continuity)

OFF
B
D
F
E
G
H
1
BO
DO
F
E
G
H
2
BO
D
FO
E
G
HO
3
BO
D
F
E
GO
HO
4
BO
D
F
EO
G
HO

A/C switch (Logic type)

  1. 1
    Check for continuity between the terminals of the heater control unit.
    Heater control unit connector terminal layout for the A/C switch (logic type) check, with terminals D and B identified at the lower-right of the connector grid.
  2. 2
    If not as specified, replace the heater control unit. (Refer to page G-43.)

A/C switch (Logic type) continuity (O—O: Continuity)

OFF
B
D
ON
BO
DO

A/C switch (Wire type)

  1. 1
    Remove the A/C switch from the switch panel. (Refer to page G-45.)
  2. 2
    Check for continuity between the terminals of the A/C switch.
    A/C switch (wire type) removed from the switch panel, connected to an ohmmeter to check continuity between terminals. Terminal layout shows E and D positions.
  3. 3
    If not as specified, replace the A/C switch. (Refer to page G-45.)

A/C switch (Wire type) continuity (O—O: Continuity)

OFF
D
E
ON
DO
EO

REC switch

  1. 1
    Remove the heater control unit. (Refer to page G-43.)
  2. 2
    Operate the REC switch and check for continuity between terminals C and J of the heater control unit.
    Heater control unit connector terminal layout for the REC switch check, with terminals C and J identified in the connector grid.
  3. 3
    If not as specified, replace the heater control unit. (Refer to page G-43.)

REC switch continuity

OFF
ContinuityNo
ON
ContinuityYes

FRESH switch

  1. 1
    Remove the heater control unit. (Refer to page G-43.)
  2. 2
    Operate the FRESH switch and check for continuity between terminals A and J of the heater control unit.
    Heater control unit connector terminal layout for the FRESH switch check, with terminals A and J identified in the connector grid.
  3. 3
    If not as specified, replace the heater control unit. (Refer to page G-43.)

FRESH switch continuity

OFF
ContinuityNo
ON
ContinuityYes
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See also

page G-44page G-45page G-43

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