Temperature Switch Odd Noise!

[Kryten]

Hi, now I may just be paranoid, having just given someone a jump-start, but when pushing the "TEMP" button for the heating, I can hear a sound like a motor or servo operating which corresponds to each push of the button, up or down.

I don't recall ever hearing this before today!

Can anyone shed some light on this?

Does something require resetting?

Thanks for taking the time out to read my post.

[Mistermena]

Got me mate!....... Have you tried to disconnect the Battery for 10 mins to see if the system re-sets?

[Kryten]

Thanks for getting back to me so soon. I haven't tried that yet but it is obviously an option.

Just so everyone's clear, I connected the leads in the correct order and connected the neg. lead to a large engine bolt (not the neg. Battery terminal) on the car to be started, last. This I am assured, is the correct way to do it.

[Mistermena]

I had wondered if you'd maybe put the leads on the wrong +/- for a moment! Hope the reset sorts it...

[junebug1701]

Hi, now I may just be paranoid, having just given someone a jump-start, but when pushing the "TEMP" button for the heating, I can hear a sound like a motor or servo operating which corresponds to each push of the button, up or down.

I don't recall ever hearing this before today!

Can anyone shed some light on this?

Does something require resetting?

Thanks for taking the time out to read my post.

It does sound like a servo motor that controls the air mix damper. You can try running the AC diagnostic. Here's the procedure on the RAV4:

CHECK MODE PROCEDURE

1. PANEL DIAGNOSIS (INDICATOR CHECK)

(a) Turn the ignition switch to LOCK.

(b) Turn the ignition switch ON while simultaneously

pressing the A/C control AUTO switch and the REC/

FRS switch.

{c} Check that all indicators and the display area are

turned on and off 4 times in succession at 1 second

intervals.

HINT:

After the indicator check is completed, the system

automatically enters sensor check mode.

(d) Press the OFF switch to terminate the panel

diagnosis.

2. PANEL DIAGNOSIS (SENSOR CHECK)

(a) Perform the indicator check.

HINT:

After the indicator check is completed, the system

automatically enters sensor check mode.

(b) Press the REC/FRS switch to enter actuator check

mode.

{c} After the actuator check is completed, press the

AUTO switch to enter sensor check mode.

NOTICE:

The sensor check must be performed again after

the actuator check is completed because sensor

check mode, which starts automatically after the

indicator check, cannot fully detect

malfunctions.

(d) Check the sensor check results displayed on the set

temperature display.

HINT:

• The illustration shows the display when code 21

is output.

• When 2 or more sensor check codes are

detected, the codes are displayed in ascending

numerical order.

• In cases with 2 or more codes, if they are difficult

to read, press the DEF switch to activate the step

operation and display them one by one.

• The codes are displayed in ascending numerical

order as the DEF switch is pressed.

(e) When any sensor check codes are displayed, refer

to the DTC chart (see page AC-39).

(f) Press the OFF switch to terminate the panel

diagnosis.

HINT:

Pressing the REC/FRS switch returns the system to

actuator check mode.

3. PANEL DIAGNOSIS (CLEAR SENSOR CHECK CODE)

(a) Inspect, and repair or replace the malfunctioning

parts.

(b) Clear the sensor check codes.

(1) While pressing the DEF switch during sensor

check mode, press the Rr DEF switch.

HINT:

Sensor check codes can be cleared by removing

the ECU-B2 fuse from the engine room No. 2

relay block for more than 60 seconds.

{c} Perform the sensor check and confirm that normal

code 00 is displayed.

4. PANEL DIAGNOSIS (ACTUATOR CHECK)

(a) Start the engine and warm it up.

(b) Perform the indicator check.

{c} When the sensor check is started after the indicator

check, press the REC/FRS switch to start the

actuator check.

HINT:

Perform the actuator check with the engine running.

(d) Check the temperature and blower levels by hand at

each step while the actuator check proceeds from

step 0 to 9 at 1 second intervals (continuous

operation).

HINT:

Each step number is displayed on the set

temperature display.

(e) To display step numbers one by one manually,

press the DEF switch to activate the step operation.

The step number changes each time the DEF

switch is pressed.

HINT:

• Each step number blinks at 1 second intervals

during the step operation.

• The illustration shows the display when step

number 5 is displayed.

(f) Press the OFF switch to terminate the panel

diagnosis.

HINT:

Pressing the AUTO switch returns to sensor check

mode.

[Kryten]

Thank you, phew! That's a lot of information to take in.

Would the fault show up on OBD reader, or is that strictly for engine diagnostics only?

[junebug1701]

Thank you, phew! That's a lot of information to take in.

Would the fault show up on OBD reader, or is that strictly for engine diagnostics only?

No, any codes that show up will be on the temperature display only.

[Kryten]

Okay, thank you.

Battery disconnected at the moment, will re-connect this afternoon and update here to report if anything has changed, otherwise I guess it's off to Mr. T. to see what they have to say about it I suppose.

[Kryten]

Okay, Battery now reconnected. It seems that the motor/servo sound has gone, except now, when I get to "LOW" (the last setting down from 16 degrees) there is a sound like a flap closing!