Rav 4 2007 (4.3) Automatic Climate Control Problems

[JTR866]

Afternoon.

I'm after some thoughts and advice about a potentially very expensive problem I have with my 2007 RAV 4 2.2D-4D XT5, to do with the automatic climate control system.

The main symptom:

No hot air from any of the vents (windscreen, face, feet) to the right of centre (offside.) Also the strength of the blown air is stronger on the offside at the same blower motor level to the air coming from the nearside vents.

Other strange things that happen with this system, 9 times out of 10 when I start the car I can't access the climate control at all for about 25-30 seconds. The light on the windscreen de-mister button just blinks once a second for about 25-30 times, none of the buttons do anything until this flashing light has stopped. If I switch the car off with the climate control on, when I come to start it up again next time the climate control will not be on but will just do the silly blink light thing for 30 seconds and I then have to turn it on manually. I don't know if these two things are normal behaviour but I'm thinking it's not.

I've run the sensor and actuator diagnostic checks that can be run on these systems using the control panel (I don't have an OBD kit, instructions found here, and codes here.) No error codes are present, except if you run this check in the garage, or in darkness, or if you cover the solar sensor in which case it shows errors 21 and 24, relating to the solar sensors.

I decided to take the vehicle to the local Toyota dealer for a diagnosis, and after having the vehicle for two days (!) I have been told that they have read error code 21(b1421) also, but that the heater matrix is "probably" partially blocked and needs replacing at a cost of £394. The job apparently requires 6hrs labour, at £468. Added to sundry items such as new coolant and possibly a new solar sensor the quote is approaching £950.

So, the questions I have,

Firstly do people agree that a blocked heater matrix can cause this, that is driver's side cold and powerful, passenger side hot and weak? I must admit I'm suspicious. Would it not wipe out hot air from the whole lot if it was blocked rather than just one side? Also why would the power of the air be different from one side to the other if the core was blocked? I would have thought that the problem is with the air mix control servo, being stuck on the driver's side to bypass the heater core, but I get no error codes on the actuator check to say that it's broken, and Toyota with the proper tester didn't read a code for it either.

What do these intermittent error codes with the solar sensors indicate? Is it normal behaviour for them to throw an error code when they are in darkness, should they be tested under full daylight, or are they actually broken?

I'd also like to know what people think about the blinking demister light upon start up. Is this normal? If not, what does it mean?

I appreciate any thoughts on this.

Regards,

Tom

[flyboyprowler]

Welcome Tom,

Sadly no expert on this one, but I am sure you will get the brains on here soon. I seem to remember that back flushing the radiator can help, and possibly a coolant change, and a look at the thermostat could help. Another maybe, could anything have got into the heater ducting to cause the problem?

I hope you get it fixed soon, it's starting to get heater weather in UK, and you will need it soon!

[anchorman]

Hmmm. Well, it wouldn't be impossible for a blocked or partially blocked core to cause it but given the flashing light (which is there to indicate a control system fault) I am more likely to suspect the control unit which has been reported several times. I think I would find a scrap vehicle for donor parts. The radiator core will only be blocked if it has been run at some time without the proper 50/50 anti freeze mix.

Changing the complete heater requires the dash out. It is a days work but not too bad if you are handy with tools. I can provide the instructions if you need them. If not I would try a good local garage to get that labour cost down.

BTW, welcome to the club.

[JTR866]

Thanks for the replies so far and the welcome.

Anchorman, I have only owned the car since August so I can't be 100% sure of the coolant history, but it has a full service history in the service book from Toyota so I would assume that the mix has been and is ok.

Do we think that there are two separate problems here then: the malfunctioning control unit, and the partial blockage wherever it may be? If so do you think it's probably best to replace the control head unit first of all to get that working right before I start replumbing it? I take it that is just the cabin control assembly on the dash or is there some ECU somewhere else?

I would appreciate some instructions for removing the dash (with diagrams if possible!) I am fairly useful in the garage but removing large amounts of trim always terrifies me that I'm going to break something. If I can study the procedure I can decide if I want to tackle it myself.

Cheers,

Tom

[CharlieFarlie]

Tom since you have only had the car that short time is there no warranty in place that would sort this ? Sounds a real pain given the time of year !

[anchorman]

pm sent Tom.

[JTR866]

I'm afraid there is no warranty, it was a private sale. I thought I checked the heater on the test drive, but the car was bought at the beginning of August and it was over 30ºC on the day so I couldn't really tell! It is annoying but I'm not that cross, this is the game you play when buying used cars privately.

[RainSong]

I have the same issue as JTR866. I have a 2008 Rav4 LE also through private sale. Had Toyota look at the issue for an estimate and they say it's the 'R/Front Servo Motor not working.'

If it is simply a blocked/partially blocked core, would Toyota overlook something as simple as clearing the blockage, and going for a more mechanical fix? It was estimated at $600.