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Discussion Starter #1
HI Folks

LR322 NZ New 02/2002, 176,000KM, V8 4.3 Petrol

I noticed some erratic HVAC fan behavior last night , winds up/down randomly but when I got in today morning entire HVAC control unit switches are dead ( no amber light on switches ) and fan not spinning .

Did the following.
  • Checked fuse 61-64
  • Plugged my simple OBII scan and got code P0135.
  • Opened the Center Right panel to visually check if any thing smoking !
I was reading threads on this issue and looks like its a common on L322.! . I had this L322 since 2009 and randomly did notice erratic behavior of the fan but not a total failure of the entire HVAC units and function.

It suggest final blower resistor could be the culprit , so will total failure of final resistor cause all the HVAC Switches and function totally dead?

Is the a fuse/ECU that controls all the HVAC switch operation ?

Don
 

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Fuse 12 feeds the Automatic Temperature Control ECU with constant 12V power. Fuse 53 feeds the ignition switch, which in turn feeds fuse 34 which sends switched 12V to the ATC ECU when the switch is in position 2(run).

RR HVAC Electric_Circuit_Diagram.jpg
 

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Discussion Starter #3
Thanks for the diagram and will check these two fuse. Do u have p/n for the hvac ecu?
 

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Land Rover Part Number is JFC102550, new its $1200. This is for the Highline ECU Auto A/C with the heated seats and its a good number for VINs after WA381431. Of course this is a North American Part Number, can't tell if its the same for New Zealand.
 

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Discussion Starter #5
Thanks for the P/N. Checked those fuse you outlined and all seems good.

Ventured further into the resistor area to see its status . Was a bit tricky and I think will have to remove the foot vent ducting to get access. Will try it again tomorrow

Also I disconnected the battery and left it for a hour hoping it would kick start the HVAC ECU . No luck.

I will try with a proper RR diag tool and get some reading.

Do you think with a blown FSR resistor , it stops all the HVAC switches and control knobs from turning on / working ?
 

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I suppose anything is possible with electronics, but that resistor is an input to the ECU not an output from it. The ECU sends it some kind of voltage and gets a signal back that it uses to control the fan speed. I guess a dead short in it could take out some board mounted component(s). Did you actually check to see if voltafge was present on both sides of those fuses, or just visually inspect them? Could be that theres no voltage at the fuses to start with. How about voltage on pin 1 of connector 1629 and 1630 on the back of the ECU itself. 1630 is a 3 pin connector with red/purple, black/slate and brown wires. The red/purple is power in 1629 is the big 26 pin connector pin 1 is in the corner of the connector with a green/yellow wire on it. Also check the brown wire from connector 1630, thats the ground connection for the HVAC ECU, make sure you have a good connection to ground.

Power to all of the O2 heater circuits comes from Fuse 3 (30A) in the engine compartment fuse panel (in the box with the ECM) so I don't think that failure has anything to do with your HVAC issues. All of the heater circuits come from the same fuse, so you have either a dead O2 sensor heater in the sensor itself, or a wiring issue to that one sensor.
 

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Discussion Starter #8
Did you actually check to see if voltafge was present on both sides of those fuses, or just visually inspect them? Could be that theres no voltage at the fuses to start with. How about voltage on pin 1 of connector 1629 and 1630 on the back of the ECU itself. ...
Good point I just tested connectivity previously and yesterday checked voltage to all the fuses above. Started to check the HVAC ECU and unplugged all connectors just to do a visual check. ( I had pin issued in the DSP AMP couple of years ago ) . Also pulled out the ecu to get the P/N.

I had to put it back to use the truck yesterday . Will continue later after work today and I forgot to test fuse 3(30A) as you outlined below. My test pen was not fine enough to test the connector pin , but voltmeter pen is .

In the pic below I can see 3 plugs in the blue ECU and 4 plugs on the silver ECU( This must be the hvac ecu ) . I can identify 1629 but can you please point in the pic 1630 location ?

Also the rear fan is not going as well , must be on the same circuit . I did not manage to get a RR scanner yet but when i used mine, the OS pending alarm cleared . ( must be when i disconnected the battery ) . I also noticed O2 2X1 0.0v and sometimes 0.4V. May be a short as you say.. Will do more voltage check today and update.
 

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Discussion Starter #10
Today morning Battery was low 11.8V and struggled to crank. I got a battery test done and looks ok ,but definitely something is draining !!.

I noticed a humming noise on the bottom left of the engine compartment . ( pic below ) . Took a video and dont know what this device is but you can feel it vibrating and humming with the keys off.

The video is at https://youtu.be/fRRyJz3Pawk

Will put in on the charger rest of the day and see if it drains tomorrow morning .

Not sure if this is related to HVAC issue but it is a RR..
 

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The HVAC ECU is actually the module in the dash with all the knobs and buttons on it, just above the center console. Connectors 1629 and 1630 are on the back of that. The two in that engine compartment box are the engine control unit and the transmission control unit (I think).

Back of HVAC ECU_L322.jpg

The rear fan and its controller gets its power from a 15 amp fuse in the rear compartment fuse is numbered 12R and it feeds a relay (R214) that is picked up by the rear HVAC blower controller, which itself is controlled from the main HVAC ECU.
 

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I'm also finding another fuse, a 25A fuse F52 in the passenger compartment fuse panel that the electrical supplement says feeds the Hevac unit but I can't find out what it feeds in the wiring diagrams I have. Might as well check that one while you have the probe out.

That thing that is humming, is your circulating water pump for the heater system , or it could be your heater control valve operators. C2035 is for the pump, C2034 is for the solenoid valves The valve manifold that lets the hot water into the two heater core sections under the dash so you can set different temps on the left and right side of the truck. Think thats the top of one of the silver solenoids right at the very top of the picture, there should be 2 of them. That's about where they are in a NA rover.
RR water pump hearter control valve connectors_L322-2.jpg
 

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Discussion Starter #13
Thanks Mark , good thing i did not poke test probe on the engine ecu.. he he !. Ok I will attempt to check the dash HVAC ECU later in the week , i just want to make sure the truck is drive-able weekdays for work . Thanks for the illustration on the HVAC module plugs .

Main test is to get a RR scanner and read faults and go forward . Also it clear now there is something draining !! the battery .

They battery guy said 748 CCA for a 9 year RR 950 CCA rated battery is ok .

Will update .
 

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Discussion Starter #14
I'm also finding another fuse, a 25A fuse F52 in the passenger compartment fuse panel that the electrical supplement says feeds the Hevac unit but I can't find out what it feeds in the wiring diagrams I have. Might as well check that one while you have the probe out.
Great information Mark , thanks, yes will check the fuses while I am testing and update.
 

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Something to note from your initial post... A standard OBD scanner will not access your HvAC errors. It will only read basic engine codes.
 

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Discussion Starter #16
The ECU removed and tested pin 1 on 1630 and 1629. C1630 power and Ground OK. C1629 Pin 1 only power when engine is running , no power on position 2 or when key removed. With the HVAC ECU removed , the rear blower started working on a constant speed. I assume its a default speed/temp. Plugged it all in and start disconnecting with key in position 2. removing C1629 , NOK REAR FAN, but with removing plug between C1629 and C1630, rear fan kicked in again. Just left the HVAC ECU out and will test if any battery drains overnight . Will try and do more trouble shooting when i get some time free.

pic of test results and video

https://youtu.be/pXFDeiaAXnY

will update
 

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Discussion Starter #18
SOLVED: Re: Totally Dead All HVAC Control switches & HVAC ??

Just a quick update , I got a used HVAC ECU Control panel for UK 70 pounds with P/N JFC000373PUY and just received today. It works perfectly now .

Thanks all for your advice pointing me to the correct information and a bit more confident now doing simple fixes like this.

Much appreciated . Pic below
 

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