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I recently fixed my HVAC screen so now everything works. Unfortunately, I noticed the book icon pops up about 30 seconds or so after I start the truck. I had the codes checked via the OBD port but nothing is showing through that route. How can I check to see what is causing the "book" fault?
 

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CMendez said:
I recently fixed my HVAC screen so now everything works. Unfortunately, I noticed the book icon pops up about 30 seconds or so after I start the truck. I had the codes checked via the OBD port but nothing is showing through that route. How can I check to see what is causing the "book" fault?
You'll need a Testbook equiped or other fully equiped shop to read your HVAC codes.
 

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No easy way to read codes. You need test equipment that is very expensive or the dealership can read them.

Read up on how the HVAC works on the main site: http://www.rangerovers.net/newrremedies.htm#airconditioning

There are many things it could be.

Also, do this diagnostic:
Range Rover HEVAC

This is really a straight forward functional test. You should have a small torch, possibly reading glasses if you use them, and maybe a straightened paper clip. Technical isn't it?
When finished you will have tested :-
the Air Con compressor (and chilled air output),
the in-car temperature sensor,
the solar gain sensor,
both blower motors,
the distribution flaps/motor,
the recirculation flaps,
and the blend flaps that mix hot and cold air.

For these first two checks, the car and engine can be hot or cold.
Identify the in-car temperature sensor, this is behind the grill positioned just below the clock. There is only one sensor.
Peer through the grill with the torch, and glasses if required. Look sideways, there is a small fan, like a drum with blades on the outside, not like a propeller / radiator fan. Without starting the engine, switch the ignition on, you should just hear the fan running, and be able to see the blur of the blades moving. As a last resort, gently, GENTLY, probe sideways through the grill with the end of the paper clip. Withdraw when it vibrates!
The fan is there to improve the effectiveness of the sensor, by drawing air across it. Fan failure won't stop the system working, but the control of the internal temperature will be poor. The heat will stay on too long, or off too long, leading to wide variations from the set temperature.

Recirculation flaps.
You need quiet for this. Turn the ignition on, but without the engine running. Wait for the brake pressurisation motor to stop running (30 to 45 seconds). Turn the Fan Speed (blower motors) down to minimum.
Operate the recirculation control and listen for the flaps moving. The noise will only last for 5 seconds or so. There is one flap on each blower motor. The blower motors are underneath the dashboard, above your kness rather than ankles, but against the outside of the car. The flap motors are very quiet. The flaps will move again when the recirculation control is restored. Repeat as required.
If you cannot hear them, you will have to test them while the car is moving. When the car is warm, switch the recirculation control on. The car will become noticeably stuffy within about 5 minutes. Switch recirculation off, and the atmosphere will clear.

Now have the engine at normal operating temperature, ticking over, with the A/C switched on.
I assume the book symbol is still showing. The system will self check every time the vehicle is restarted.
If the fault disappears, so will the symbol.
Compressor / chilled air faults will be self evident throughout these tests, no Cold Air.
If this is apparent, open the bonnet, and with the engine running, have someone switch the A/C on and off. There will be an audible click from the Compressor as the clutch engages. Placement of the compressor varies from engine to engine.
Remember, in the absence of chilled air, either through a faulty system, or because the A/C is switched off, the system will substitute external air, at the ambient temperature. In some parts of the world (rarely in the UK) this can be hot. Thus sometimes "cold" air is hot.

Distribution Flaps.
Set both Driver and Passenger temperatures to 16.
Turn the Fan up to get a decent airflow, that is half or threequarter speed.
Using the manual buttons, direct the air towards the footwells. Check with your hand that the airflow is of similar strength and temperature.
Note any side to side differences.
The air issues from triangular holes on the sides of the transmission tunnel above your ankles.
Check there is no air flow from the Facia or Screen outlets.
Use the buttons again and divert the air towards the facia vents, remenber to have them open, check again for flow and temperature.
It takes a few seconds for the Distribution flaps to move to the new position.
Check there is no flow from the non selected outlets (Footwell and Screen).
Use the buttons again and divert the air to the screen, check again for flow and temperature, especially any side to side differences.
Assuming the airflow moved correctly from footwell to facia to screen, and DID NOT appear from any outlets that were not selected at the time, you have proved the Distribution flap / Motor works.

Blower Fans.
With the air issuing from whichever vents you find most convenient to monitor, turn the Fan speed up and down.
Check the air flow varies on both sides of the car. There are two Blower motors, one Left, one Right. They should both change together as you adjust the speed.
Assuming they do, you have just proved the blower fans work. Leave them on half or threequarter speed.

Blend Flaps.
With the air issuing from whichever vents you find most convenient to test, raise the Drivers side temperature to 22, wait a few seconds, can you feel a temperature difference when comparing Driver side air ouput to Passenger side air ouput?
Raise the Drivers side to 28, there should be an obvious difference in temperature.
If the Drivers side airflow temperature has not changed, the Driver side blend flap is faulty.

Reset the Driver side temperature to 16, then repeat the test, varying the Passenger side temperature.
If the Passenger side airflow temperature does not change, the Passenger side blend flap is faulty.

Solar Gain.
The solar gain sensor is a black button on the centre top of the dashboard, near the windscreen (near the Alarm LED).
With engine ticking over, and A/C on, switch it to AUTO mode. Adjust both temperatures to a medium/ low setting, (16 to 22) and let the system stabilise, with the blowers running but not too fast. Shine a bright torch on the Solar Gain sensor, it may take 30 seconds or so, but you will hear the system adjust to compensate for the additional heat, probably by increasing the fan speed. Remove the torch and the system will adjust back, give it a minute or so.
If the system compensated for the additional heat, the solar gain sensor works.

In car temperature sensor.
This is situated behind the grill below the clock.
With the system set as for Solar gain, heat up the Cigar Lighter, and hold the hot end in front of the grill, but not close enough to melt the plastic!
1 to 2 cm should be fine.
If the system compensates for the additional heat, the in-car sensor works.

Additional information.
When on Auto, if a number is showing in the temperature setting, the system will control the position of the blend flaps, dependant on internal temperature, external air temperature, etc.
If you adjust the setting to LO, the blend flaps are forced to the end of their range, to deliver ONLY cold air, whatever the actual temperature is, inside or outside.
Remember Cold air will be hot if you are in a hot climate and the A/C is switched off.
If you adjust the setting to HI, the blend flaps are forced to the end of their range, to deliver ONLY heated air, whatever the actual temperature is, inside or outside.

That's it, you should now know what functionality is absent, and can start checking repair costs, or read the (future) article on known faults, repairs and workarounds.
 

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Sorry to hijack this thread, but my issue would be relevent to some one searching for an answer.

Thanks spike end for that info. The book symbol on my 98 has been on since I bought it last year, but all I noticed was the demist on the pass. side didn't blow out very well when on program, so I didn't bother with it. Now this summer, the A/C quit working, but the compressor is cycling properly, the low side is cold to the touch, and seems to be working as a refrigerant unit should work. No matter what I set the temp to on the controller, there is no change what so ever in the temp coming out of the vents.

I noticed that when first starting up the engine, cooler air will blow thru the vents, but as soon as the engine comes to temp, hot air is all that will blow no matter what the controller is set at. It's like the blend motors have defaulted to heat, or both of them are just stuck in the heat position, and failed there. /:(

What if any of the test that spikeend has listed could aid in my diagnosing this unit? What really sucks, is I have more than one scan tool that I have alot of money invested in in my shop but cannot access the HEVAC, so I have to do it the old fashioned way. BTW, distribution seems to be working fine as I can change the air flow to any section with the controller.

Thanks for any input, as I would love to fix this myself.
 

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First off, I must admit that I did not come up with the write-up myself, but found it so useful that I keep it handy and have posted it a few times.

Sounds to me like your distribution flaps or blend flaps are not working properly. I recommend you go through it step by step and then report back which steps are not working properly.
 

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JACK'S GRANDAD
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Tom, if you can live without it for a few days, I will hook it up to the MSV when I get home and tell you the faults. All it will cost you is postage mate :thumb:
Shoot me a PM if need be and we will see if we can coordinate it all in a timely manner.
Try the tests first, and when you start banging your head too hard against the brick wall, let me know :wink:

Martin
 

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Thanks Martin, right now I too busy working on other peoples cars, so i'm not going to get at it right away anyhow. It's not a daily driver, so no biggie, one day I'm gonna sell it,,, the next day,,, I'm gonna keep it and fix it up. :roll:

My Launch X431 Diagun does have HEVAC, but there could be an issue with the DLC, as there is no communication. I haven't even checked the 5amp fuse yet. Once I get on it I will get with you.

If it is the blend motors, hopefully Scotty has those new ones from the red car laying around. :dance:
 

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LEGACY VENDOR
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spikemd said:
In car temperature sensor.
This is situated behind the grill below the clock.
With the system set as for Solar gain, heat up the Cigar Lighter, and hold the hot end in front of the grill, but not close enough to melt the plastic!
1 to 2 cm should be fine.
If the system compensates for the additional heat, the in-car sensor works.
Usefull write up. Sometimes physical tests gives more infos than Testbook

Do you think we could use the in car temp sensor with an interface and a display to show exact temp in the car.
 

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I had the same problem and used a tool called Autologic. I would recommend Autologic as it works for cars other than Range Rovers.
 
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