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Discussion Starter #1
Ok, so I have been trouble shooting this for sometime now. I get the dreaded open-book! symbol only when it is greater than 90F out. For the past few weeks, I thought it was only when the A/C was on, hence the reason last weekend I bought a full set of AC gauges and some R134 to recharge the system but haven't done it yet. The A/C still works even when the symbol comes on, but I thought it was low on R134 and I was going to top it off. I have RAVE and the correct pressures for the high and low side, but now I don't think the AC may be the culprit... Because yesterday the **** symbol came on without the AC running!

Let me start at the beginning... I first noticed it in July when the temps rose above 90F and I was using the AC. The book symbol came on so I started combing the forum for information on this new gremlin. The forum is truly awesome, by the way...

I started with relays. Noticed a few of mine were cooked and bought 8 new ones. I also noticed the fuse box had a small crack around RL7 but wasn't totally cooked like some of the other pics I have seen.

Using the abbreviated guide I found, it helped me rule-out a few things:

Recirculation flaps - seem to work

Distribution Flaps - checked out, flow where there should be flow

Blower Fans - these I was worried about given the relays were cooked. Both seemed to check out and air flow seems consistent on both sides. They keep spinning even when symbol comes on.

Blend Flaps - adjusted temps and they appropriately 'blend'. In addition, the symbol does not come on immediately as appears to be the case with some blend motor issues.

Solar Gain -tried to test it, seems to work, but I can't be positive.

In car temperature sensor - noticed that it was not spinning. Got it spinning with a nudge of a paperclip. Seems to intermittently stop, but starts with some subtle pounding.

So what really threw me was yesterday with the temp above 90F, no AC on and the book symbol came on! I tested it again tonight and it takes about 10 minutes for the book symbol to come on. It comes on initially, then goes away for a few seconds then seems to stay on. It comes on even with the in-car temp sensor spinning. I turn the truck off, turn it right back on (not making any adjustments) and the symbol is off again for some time. Since it came on without the AC running and the AC still blows cold even when it is on, I may hold off on checking the AC levels/pressures. It does seems to come on more consistently with the AC running.

Please help shed some light on this. Ideas right now-

- fuse box is cooked and it is getting hot and flipping the symbol on
- the blower motor relays keep tripping in the heat, even with new relays. Might be related to fuse-box issue
- AC is low and needs a recharge
- in-car temp sensor is bad, even with the fan running
- outside temp sensor is bad, eventhough it seems to be pretty accurate on the HEVAC display

any other ideas?? thanks.
 

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Hi Spike,
Well the only things you havn't mentioned is that you have cleaned and replaced the pollen filters.actually checked for for code faults on Faultmate SMV-2 , Rovacom and thirdly the temp sensor on the inlet heater water pipe could also be faulty.
The fuse box should be replaced on these cars every 5 years as the common fault with the blower relays overheating and cooking everything :(
Checked the clutch on the compressor, remove spacer if gap to large. Climate controller working corectly and fan adjustments are working in manual mode? Servied air con system by a professional and relplaced condensor dryer
Thats it
 

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Might not be any help, but on mine the little fan inside under the clock stopped turning, cleaned it out and gave it a tap now turns and no book!!
 

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Discussion Starter #4
Thanks. Yes, I did change the pollen filters first thing. Unfortunately, I don't have a faultmate to give me a reading of the fault and i don't want to take it to a shop to get it read. The clutch on the AC is working and the AC keeps working even when the book symbol comes on. Fan adjustments work well on manual mode.

First step, I will take out the in-car temp and clean it since it wasn't running when I checked it. I will try to check the other temp sensor.

Next, sounds like I need to replace the fusebox. It looks original. It doesn't look too bad, but yes, one of the slots t RL7 does show a crack in it. The symbol seems to come on after about 10 minutes or so making me believe it could be when things heat up and causing the fusebox to act up.
 

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how about pressure on the A/C system :think: - mine went a couple of months ago - in the middle of the summer -took me 2 short drives to decide it had to be fixed NOW!!!! - 1.5 hour later it had a new condensor and fresh gas again - and cools now to 4 degree celsius.... brrrrrr! No booklet since then - and filters are changed regularly... servomotors seems fine - just don't tell the car... :pray: :shhh:

You're never bored with a british car - or girlfriend..... - 10 year old car and 5x-year old girl....oups did I write that - better watch out now
 

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Discussion Starter #6
UPDATE:

Fixed this with a new fusebox. Thanks SHUPACK for the Turkey Day sale. Everything works now!

My fusebox showed some cracking in it and burned through more relays. If yours shows any cracking, don't replace blend motors or blower motors until you have a new fusebox.
 

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Discussion Starter #7
I realized I didnt put in my testing criteria. Here it is:

HEVAC Testing:

This is really a straight forward functional test. You should have a small torch(flashlight), possibly reading glasses if you use them, and maybe a straightened paper clip.

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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Hi I have read your post about your work on the HEVAC system with great interest and admiration. I have followed what you have advised, but I have just about given up hope of ever fixing my 2001 Holland & Holland heater and A/C. I have replaced the control unit (with the same part number unit from a known working car), I have replaced the blend motors (all of them), external temp is working fine, the heater core sensor (clipped to the pipe) switches the unit on to Defrost Program (if selected) when up to temp, in car temp sensor clean and the fan is working, but I cannot get rid of the dreaded BOOK symbol and the blend motors don't function when the buttons to divert the airflow are pressed. I currently have the inside of the car stripped, no dash or seats so can pretty much get to everything. If I start the car with the unit in Auto the BOOK stays off until the system wants to move the blend motors then on it comes. Is there anything else that can bring on the BOOK symbol???

Any help would be greatly appreciated, this is my second P38 and my seventh Range Rover it only has 72,000 on the clock and the engine is as sweet as a nut now that I have fixed the overheating problem, (for those that have a similar overheating problem, mine was a tiny hole in the metal pipe from the reservoir/expansion tank to the thermostat housing, causing the system to never get to working pressure and therefore boiling).

I am fast getting to a point where I might just sell it for scrap and buy a Toyota!!!!!!!!

Thanks in advance....
 

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Hi Alan

There are 2 more blend motors on the recirculation flaps. This are the motors that do not have a feedback potentio meter to the ECU and the stalling of the motor is detected by the increase in the current. If these motors fail or are stuck it will also flag the book sign. These motors are moved every time during start up as a part of the self check of the system.

The distribution flap could be jamming. There is a post on this forum that describes on where to insert a self tapping screw in the housing to make more room to free up the flap. After doing this it was reported by several owners here that it helped to solve the problems.

Good luck

Jos
 

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Hi Jos

Thank you very much for the info and the very quick response, I hadn't expected anything back so soon. I checked these recirculation flaps and both operate fully when selected, the drivers side is a little jerky but does complete its movement. Would you expect the book to come on if they are disconnected? I unplugged them and there is no difference, the book comes on within a second of switching the ignition on, dissconnected or not. It is below freezing here now so am not planning to go out to the car again today, but I will measure the current draw of these motors at the weekend and compare it to the blend motors.

Many thanks Jos..
 

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Hi

The system is doing a self check at start up and flags the book sign if something does not pas the test. This can also be related to the pressure of the R134A gas in your AC or any of the sensors that measure the temperatures and pressures.

To be sure what the problem is you have to get the fault codes from the ECU.

Regards

Jos
 
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