PTC Heater Circuit

AIR CONDITIONING: AIR CONDITIONING SYSTEM: PTC Heater Circuit

PTC Heater Circuit

DESCRIPTION

PTC heater relays are closed in accordance with signals from the air conditioning amplifier assembly and power is supplied to the PTC heater assembly installed on the radiator heater unit.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. INSPECT FUSES (HTR SUB 1, HTR SUB 2)

(a) Remove the HTR SUB 1 and HTR SUB 2 fuses from the engine room relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(c) Reinstall the HTR SUB 1 and HTR SUB 2 fuses.
NG -- REPLACE FUSE
OK -- Continue to next step.
2. INSPECT HTR SUB RELAY (HTR SUB 1, HTR SUB 2, HTR SUB 3)

(a) Remove the HTR SUB 1 relay from the engine room relay block.
(b) Remove the HTR SUB 2 and HTR SUB 3 relays from the No. 2 engine room relay block.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(d) Reinstall the HTR SUB 1 relay.
(e) Reinstall the HTR SUB 2 and HTR SUB 3 relays.
NG -- REPLACE HTR SUB RELAY
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (FUSE - PTC HEATER RELAY)

(a) Remove the HTR SUB 1 relay from the engine room relay block.
(b) Remove the HTR SUB 2 and HTR SUB 3 relays from the No. 2 engine room relay block.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:

(d) Reinstall the HTR SUB 1 relay.
(e) Reinstall the HTR SUB 2 and HTR SUB 3 relays.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - BODY GROUND)

(d) Reinstall the HTR SUB 1 relay.
(e) Reinstall the HTR SUB 2 and HTR SUB 3 relays.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. PERFORM ACTIVE TEST USING TECHSTREAM (HEATER ACTIVE LEVEL)

(a) Remove the HTR SUB 1 relay from the engine room relay block.
(b) Remove the HTR SUB 2 and HTR SUB 3 relays from the No. 2 engine room relay block.
(c) Connect the Techstream to the DLC3.
(d) Turn the ignition switch to ON.
(e) Turn the tester on.
(f) Select the following menus: Body Electrical / Air Conditioner / Active Test / Heater Active Level
(g) Measure the voltage when changing the control range with a Techstream, according to the value(s) in the table below.
Standard voltage:

(h) Reinstall the HTR SUB1 relay.
(i) Reinstall the HTR SUB2 and HTR SUB3 relays.
NG -- CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.
6. INSPECT PTC HEATER ASSEMBLY

(a) Disconnect the A18 PTC heater assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(c) Reconnect the PTC heater assembly connector.
NG -- REPLACE PTC HEATER ASSEMBLY
OK -- Continue to next step.
7. PERFORM ACTIVE TEST USING TECHSTREAM (HEATER ACTIVE LEVEL)

(a) Disconnect the A18 PTC heater assembly connector.
(b) Connect the Techstream to the DLC3.
(c) Turn the ignition switch to ON.
(d) Turn the tester on.
(e) Select the following menus: Body Electrical / Air Conditioner / Active Test / Heater Active Level
(f) Measure the voltage when changing the control range with a Techstream, according to the value(s) in the table below.
Standard voltage.:

(g) Reconnect the PTC heater assembly connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (HTR SUB RELAY - PTC HEATER)
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
8. CHECK HARNESS AND CONNECTOR (PTC HEATER RELAY - AIR CONDITIONING AMPLIFIER)

(a) Remove the HTR SUB 1 relay from the engine room relay block.
(b) Remove the HTR SUB 2 and HTR SUB 3 relays from the No. 2 engine room relay block.
(c) Disconnect the G8 air conditioning amplifier connector.
(d) Measure the resistance.
Standard resistance:

(e) Reinstall the HTR SUB 1 relay.
(f) Reinstall the HTR SUB 2 and HTR SUB 3 relays.
(g) Reconnect the air conditioning amplifier connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE AIR CONDITIONING AMPLIFIER