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P38 HEVAC persistant problem HELP REQUIRED PLEASE


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X Reg 2000 P38

Handbook ! sign checked by a Landrover specialist back in Feb. Controls not sending air to footwell. Blend moter problem diagnosed. Blend moters replaced.

No improvement!

After much more investigation, front contol panel of HEVAC replaced. This worked

For three whole journeys!

Then same fault appeared. No air to footwell, HANDBOOK ! sign up on display.

I actually sat in the car as the Landrover specialist (independent mechanic who used to work for a Landrover main dealer and who was recommended to me by a reliable source) checked the system on a laptop which showed the same fault as previous which was a blend moter fault


Blend moters were replaced again as there was a suspicion that the original replacements were faulty

No improvement

Tried different HEVAC front panels that he had from previous repairs which had known faults i.e. would not work on AUTO and something weird happened, the system worked!

Then failed again after a while with the laptop returning the same fault details

He tried another HEVAC front panel and that got rid of the HANDBOOK ! and the air would be directed correctly according to the buttons pressed but the aircon refused to function

The HEVAC front panel was replaced by a brand spanking new one

It worked

For a while

And now is back to the HANDBOOK !

If anyone has any ideas, please help



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Get yourself hooked up with the www.rangie.com mailing list, and check the articles to be found on the site. There is a MASSIVE amount of P38 specialist knowledge via email on there, lots of very clever guys who have had the same sort of pain as you are.

I'd like to help, but my 83 RRC only has 3 fuses, and I still cannot fix the u/s fag lighter sockets......




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Mike, I threw your post onto the Rangie.com mailing list and got this back, hope it helps in some way:

It would be easier to replace the control panel with the manual panel out of the early lower spec cars. The blend flaps were operated by cable. If one removes the flap servo motors in the up-spec models, one can see that there is provision for operating the controls by cable. See one of my pix taken in a wrecked P38A a which clearly shows this at http://rangerovers.net/repairdetails/blendmotor.html

However, if one wanted to retain electronic control, no, the servos are not stepper motors. I show pix of one on the above page

They are pretty much like a model plane/car radio control servo but the electronics are contained in the control panel. An ordinary DC electric motor drives the output shaft through a gear train. There is a feedback potentiometer (not seen as it is driven by the gear in the top left corner) connected to the gear train which feeds a voltage back to the control panel telling it how far the shaft has rotated.

Also got this, so you know you are not alone:

HVAC has by far been the most frustrating and expensive part of p38 RR ownership for me.

After spending far too much $$$ on my HVAC with it still not working this is not funny, especially dressed for a wedding : (

Recently I was a passenger on the sunny side for a three hour ride to a wedding on one of the hottest days of the season. The aircon stopped working yet *again* only five miles into the journey. Can you say melted upon arrival? Taking the series would have been cooler, but we would have had to leave a day earlier ; )

It had been working intermittently since the last repair in May (drier, condensor, 1999 head) only if it was shut off for about 15 minutes then it would work again for a short while. This time it didn't revive, it just stopped working completely and the open check book sign came on.

After getting it back to the independent last week he came up with the following autologic faults:

freon low with a new leak found at the firewall - was leaked tested in May, he mentions there could unseen leaks inside the dash as well. Oh joy.

left blower motor circuit fault, relay replaced

condenser for control circuit fault, condenser was replaced in May

A/C request signal circuit fault

ambient temp sensor fault - this was just replaced in May when the condenser/drier was replaced. His part supplier suggests it's not a faulty sensor but requires upgrade to new head and sensor location.

It had stopped working shortly after the condenser/drier replacements were done. The independent said it is the head since it can't be anything else. Head was replaced from a 1999 vehicle in late May by me. A new sensor/location was not upgraded. AC worked again for a short while until it finally died en route to the wedding.

Autologic says it's showing a 30 degree temp difference and that a new head$$$/new sensor location will fix this...hmm

heater core temp sensor fault, replaced heater core sensor

new leak at the firewall was found but independent is out of freon for the season after topping off this last leak so he says it should get me by until next year. Not very pleased hearing this, guess we can start all over again next season.

It was dye leak tested and recharged when the condenser was replaced in May.

This whole nightmare started four or five years ago when I had it to a LR dealer for recall replacements. The open check book had come on back then and their test book said blend door fault. The recall repairs were more important at the time so they didn't touch the AC issues since it started to work again after the faults were cleared.

On my way home from the dealer, guess what? It stopped working again and it's been like this every year since.

Does the car just hate me?

It's back at the LR spa. On the way home from picking it up Wednesday after I was told it works fine, it stopped working again as I headed home so I went straight back to the garage. Hood open tap, tap....oh it looks like it's the shim this time.

I've yet to hear the outcome, it's an hour and a half ride to pick up this weekend.

Looking forward to hearing any suggestions even if it involves a for sale sign or exorcism.

Also looking forward to fall.

Lori in PA USA

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It sounds like an intermittent electrical fault to me, maybe dodgy connectors or wiring loom.

I have the exact same problem on my 1998 P38 - occasionally the blend motor stops functioning and the book symbol comes on. I have twice stripped the console and dash, only to find the blend motor working again. I have stripped the motor and checked it thoroughly, to find nothing wrong with it at all. I guess it could be the control unit but replacing it would be a last resort for me.

Since you have replaced the HEVAC control unit and the blend motors, the only things remaining are the wiring loom and connectors. I have had wiring loom faults in the past on a Classic and in my current P38 so it seems quite a probable bet.

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Very new to this forum but have had my 97 hse for the past 2 years also had problems with hevac for that time? Was told blend motors etc, but did not make sense as under manual control all good. 2 different dealers. 3rd dealer said two many faults in system but believed it to be coolant sensor on heater core. After 2 visits reduce logged faults and arrival of part, sensor replaced all good now. Probably not related to you fault, but having worked in design and development of Auto climate control systems for Ford Mo Co ( Bosche hardware our program) they can be a pain. It does seem that you have done the basics not familiar with rovercom but most systems will only fault when sensors go out of range this can be a sensor fault or wiring etc as you have stated. Any way but was told by dealer if one sensor faults the range rover systems faults lots of others follow suite. Yes could be a wiring problem before you replace loom check all connectors when I was at ford occasionally we would have connectors not locked into there sockets so when the connector was mated the pin would push the receptor out of position. But have to say after 30 years in the industry it is still the simplest of things that create a problem not the more difficult ones. When friends ask me to look at their vehicles I start from the very basics and most of the times it works. Having said what I have to admit that the Range Rover auto climate control is fairly average. At the moment you seem to be on the back foot will talk to person at dealer I went too.He seems to know his stuff. Hope I can help.

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