Hi all

This has been a very long saga, but to keep things as brief as possible, I've been investigating an AC fault on this 2005 Alphard Hybrid for quite a while and it looks like there may be a fault with the AC amplifier. Basically, the voltages going to the inverter converter from this amplifier as non existent. I've checked it all out against another vehicle with working AC to confirm this. All of these voltages come from the AC amplifier (see photo) but I have no idea where this is located in the vehicle. Any ideas?

The fault code I've retrieved from the climate control panel (code 98) reports communication error between inverter and hybrid control ECU. This is a generic description, so I don't really think it is helping a great deal. As a result of this, the AC compressor is not activating.

I have really struggled to find any technical information for this vehicle, so any help would be much appreciated.

Cheers.

Have you check our wiring diagrams section?

From looking at the part catalogue, it appears to be hidden in the dash attached to the heater unit.

15 hours ago, smurf said:

From looking at the part catalogue, it appears to be hidden in the dash attached to the heater unit.

Thanks for your reply. I had come across this diagram online. It's just a shame it isn't a little more specific as to where exactly this unit is fitted. I guess it's above the heater box somewhere, so it looks like I'll be removing the dash next. Great...

I have another picture for the location of the 2-way compressor control amplifier and it is to the side of the blower, possibly get access by removing the two passenger storage bins and the trim panel. From the manual, which I have nearly finished translating, It outputs a compressor drive signal to the A/C inverter according to the operation enable signal from the HV control computer and the signal from the dual automatic air conditioning computer. In addition, when belt drive is used, it inputs a variable capacity signal from the dual automatic air conditioning computer to control the compressor control valve.

The computer is built into the control panel. There is a self test that can be performed on the panel;

While simultaneously pressing the "AUTO" switch and the "Inside/Outside Air Change" switch on the control panel, change the IG switch from the OFF position to the engine start position.

When panel diagnosis is activated, an indicator check is performed automatically.

Check that all indicators and setting display sections light up and go out four times at 1 second intervals.

Once the indicator check is complete, a sensor check will be performed automatically. Press the “inside/outside air change” switch to perform an actuator check.

After the actuator check is completed, press the “AUTO” switch to perform a sensor check again.

The result of the sensor check is displayed on the set temperature display. To end the panel diagnosis, press the “OFF” switch.

[Electronic Technical Manual] AC fault codes.pdf

Wiring diagrams attached

hdam3860.pdf hdam3810.pdf hdam3820.pdf hdam3830.pdf hdam3840.pdf hdam3850.pdf