Possible Heater Matrix problem?

Hi guys,

I'm knew here and dont know as much as i'd like to about cars so please be nice!

Was driving along through the town in my 1997 Range Rover P38 and I suddenly had boiling water spraying out from under the steering wheel and onto the footwell. I believe that because of the boiling water it caused the cabin to steam up. Lots of steam was coming out from near the pedals/under the steering wheel and put a lot of condensation onto the speedo/dials.

I pulled down the windows and pulled over and checked under the bonnet for another obviously wrong.

Spoke to the guy I bought it off and he said to fill up the water and it sounded like "one of the o-rings had gone with the Heater Matrix" which didnt make any sense to me.

I noticed that the water temp in the car increased as I was driving quite quickly so I had to keep stopping and topping up with water/letting it cool down.

Anyone had any experience/problems with this? Will it be an expensive fix? The guy I bought it from said he will come up and fix it (hes a mechanic) but im not holding my breath on him as he has work Monday-Friday and this is now my only car to get to work with!

The heater (behind the dash) has two pipes that are connected to the pipework from the engine using rubber 'O' rings to seal the joint. It sounds like one of these joints has given way.
The water in the heater is also your engine coolant so continuing to drive your car with essentially no engine coolant will lead to a failed engine.

Yeah, I figured that driving with high temps wouldnt be a good idea for a long period! I was only 5 miles or so away from home and had 3 stops in that time.

I think the guy im bought it off is coming up tomorrow to fix it, so fingers crossed it should be fixed pretty soon. He said its all behind the dash board and will take a while to get in there.

Sin said:

will take a while to get in there.

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He's not wrong, however watch what he does because there are a few little faults on these that mean that you need to get behind the dash so knowing how could be helpful in the future.

Talking of the future, if you come up with more issues it's more helpful if you tell us which engine and stick your location into your details. There are a few on here who are willing to travel (a bit) and advise fellow members. The usual bribery is cuppas and posh biccies but the offer of a bacon butty can get interesting results.

Welcome by the way.

Bloody hell, I'd cook a roast dinner if it meant getting the beast back on the road! haha.

Its a 4.6 HSE with auto transmission. I live on the Surrey/Kent border.

I'm really eager to learn more about the car, but I'm only 19 and my previous mechanical experience is solely based on Motorbikes!

Search the threads on here for RAVE, the complete workshop manual on PDF. Every single job of work on the car is detailed as are the capacities, lubricants, wiring diagrams etc.

Download it for free and start reading - if you are going to keep your rangie you will need RAVE.

Thanks, Downloading it now.

Does anyone know of anyone that is around the Surrey/Kent way that could be willing to help me out on this one?

I could take off the dashboard/steering wheel but dont have the confidence to do this myself without screwing something up.

I'm worried that if I go to a garage that I will get fleeced or they will charge a LOT purely on labour (I've been told its not a 2 second job and will take a couple of hours).

It just needs the O rings replaced on the heater matrix.

Sin, try reading "Heater O Rings" here:

Range Rover P38/4.0/4.6 Common Problems and Fixes

Okay, the man fixed it yesterday which is all good and its no longer leaking boiling water.

He said that the pipes came out because of a brass thread and that meant the hot water pipe was just loose, thus spraying boiling water out everywhere.

He told me to take it for a drive to check it out after he left. After he left I realised that the heater/air con doesnt work at all now. I can change the temp but when I go to change the fan speed it doesnt have any effect which means I cant really demist my windshield or rear window.

I spoke to my Grandad and collegue at work and they both said that it sounds like because he was in a rush he forgot to reconnect the fan or a wire has been misconnected.

He didnt have to take the dashboard apart, he only opened bonnet and unscrewed the panels under the steering wheel and side of the heater. Is this something easy that I could do myself? I dont know exactly what I would be looking for and dont want to mess around without proper guidance as I fear I would do more harm than good!

Just tried to get behind the Heater unit but the trim that goes from the storage box between the two front seats has plastic covering the screws and it seems really hard to get access to the screws without snapping the plastic.

Not a clue how to get these panels off!

I believe to remove the side panels, you first have to firmly pull downwards the side strips on the centre console part....

I attach a section from the WSM....

if the o rings are done correctly you can sort the job in about 4 - 6 hours.
Did he fit new o rings when he was in there ?

I think he said he did replace new o-rings and he used a way more "reliable" bolt to hold the pipes in place. When he talks about it, he doesnt really dumb down anything so he could be talking chinese for all I know I try to keep up though!

The whole job took him about 2 and a bit hours, far less time than I thought it wouldve been, but I guess this is because he knows the car inside out.

Thanks for the Diagram. Will have a look the car in a bit.


I just got a text back from him and he said its possible that Coolant has gotten onto the electric and he definitely didnt disconnect anything. He told me to see if it dries out and starts working again, but its been a day since then and ive driven it about 35 mins so far and it hasnt turned back on. He said that he will "look to see where the fuse is and it may self cure when dried out."

There is a small temperature senser that clamps to the heater pipes just behind where the O rings are fitted.

This senser, tells the HEVAC system when the Coolant has got to a sufficent temperature to start the fans, (it is there so you don't blow cold air in on a cold day, until the heater has warmed up). I am not sure but if this has been disconnected, the system will think the heater is cold and as such not blow any air in.....

That being said, if you turn the dial fan speed control, it should override this and increase the fan speed.....

Does anyone know if this little senser will stop the fans blowing on manual control?? as a sort of 'fail safe' or interlock mechansim??

I dont know about overiding it, but if it makes it any clearer there is no difference in the blowing speed when I turn the dial fan speed control from idle to full. Absoloutely none.

Where abouts in Surrey are you based Saint V8?

Does the fan turn at all but doesn't increase or decrease...??

Does the display show the lines at the top indicating fan speed??

It could be the dial knob itself is kerput...has been known, do search on here and see if anything is mentioned about a fix...

I live near Bisley....

Saint.V8 said:

Does the fan turn at all but doesn't increase or decrease...??

Does the display show the lines at the top indicating fan speed??

It could be the dial knob itself is kerput...has been known, do search on here and see if anything is mentioned about a fix...

I live near Bisley....

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I'm not sure if the fan turns? I dont hear anything and i dont feel anything coming out. Just seems dead.

The display shows the lines indicating fan speed though, thats what confused me about it.

The dial knob/fan was working perfectly before the bloke "fixed" it.

Just no pressure coming out so it wont actually blow it out. I can feel a temp difference if i turn from "lo" to "high" using the dial but only if my hand is pressed against the vent.

Have a look at Fuse 34 in the engine compartment - you never know.

Sounds like either the fans (there are two of them) are disconnected or as KieronF says, the fuse has gone....Thought the message centre told you if a fuse has blown...or is that only for certain fuses and not all of them??