Inspection Procedure

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

Check converter circuit . See CONVERTER CIRCUIT .
Check voltage between terminal HTR0, of A/C amplifier and body ground.
PREPARATION: Remove the center cluster module control with connectors still connected.

Check
1. Start engine.
2. Set temperature control switch on "MAX WARM" position.
3. Set blower switch on "HI" position.
4. Turn light control switch to OFF.
5. Turn defogger switch OFF.
6. Check voltage between terminal HTR0 of A/C amplifier and body ground at each conditions, as shown in the chart. See Fig 2.
  
  Fig 1: Locating A/C Amplifier Terminal HTR0
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 2: A/C Amplifier Terminal HTR0 Terminal Specifications (Connector Installed)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. OK: Go to step 6.
2. NG: Go to step 3.
Check HTR1 and HTR2 fuses.
PREPARATION: Remove the HTR1 and HTR2 fuses from engine room R/B NO.3.

Check: continuity of HTR1 and HTR2 fuses.

OK: Continuity exists.

Fig 3: Locating HTR1 & HTR2 Fuses
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Check for short in all the harness and components connected to the HTR1 and HTR2 fuses. See Figure.
2. OK: Go to step 4.
Check HTR1 and HTR2 relays.
PREPARATION: Remove the HTR1 and HTR2 relays from engine room relay block NO.3.

Check: continuity between each pair of terminals shown below of magnetic clutch relay. OK: See Fig 5.

Fig 4: Identifying HTR1 & HTR2 Relay Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 5: HTR1 & 2 Relay Specifications
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PREPARATION: Apply battery positive (+) voltage between terminals 1 and 2.

Check: continuity between terminals 3 and 5. OK: Continuity exists.
1. NG: Replace HTR1 and (or) HTR2 relay.
2. OK: Go to step 5.
Check harness and connector between A/C amplifier and HTR3 fuse . See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION .
1. NG: Check and replace harness and connector.
2. OK: Check and replace A/C amplifier.
Check PTC heater (Heater Radiator).
PREPARATION: Remove the heater radiator. See step 8) of AIR CONDITIONING UNIT DISASSEMBLY .

Check: continuity between terminals of PTC heater connector. OK: Continuity exists.

Fig 6: Testing PTC Heater Continuity
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Replace heater radiator.
2. OK: Check harness and connector between PTC heater and HTR3 relay, PTC heater and body ground. See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION .