How to change the heater matrix (from old site)

This article has been copied and pasted from the old website.









Need to replace the heater matrix? Here's a detailed guide on what to do.


As any of you who have attempted this will know, changing the heater matrix on a Renault 5 GT Turbo isn't a nice job. It's a horrible one. In fact I think Renault sat around a big table with a heater matrix in the middle and said "So what can we bolt on to this then?" Take a few tips from this guide and it should (hopefully) make the job a little less annoying. And by annoying what I mean is, well see the old matrix at the end of this article!

So you've probably got water all over your interior, and soaking wet carpets, particularly collecting under the seats. I spent a few wet days trying to find out exactly where this was coming from. I was losing water from the expansion tank, but I actually found a split water pipe. Having changed this and still losing water, the search went on.

You might want to do a few easier checks before trying the matrix. Check your door seals are not leaking, and that the doors are set in the right position with the hinges and pins in good condition as in heavy rain it can get in here. Apparently there are also drain holes in the bottom of the doors that let out water that has collected inside the doors. These can get clogged and collect water and let it run into the cars interior, so unblock these if they are clogged.

Although if you're loosing water from the expansion tank, you have checked all pipes, radiator, there are no engine probs like head gasket, etc and you have wet carpet, then it's probably the heater matrix.

Mine started off as a small problem, only loosing the expansion tank supply over about a week. It then went to loosing the lot just by booting it a mile down the road and back. With water visibly collecting round my feet, it was a pretty sure sign the matrix was devil spawn.

By-passing the heater matrix

The first bit of good news is that you can disconnect the matrix and still use your car, minus it's heating obviously. I drove for months and months like this, but with winter setting in, decided to get the job done. To do this you need to disconnect the heater pipes from the matrix and join them together. These go into the matrix on the bulkhead behind the turbo (see step 2 below). I'm not sure if it matters, but it might be best to note which pipe is top and bottom. Drain the cooling system and remove the pipes. I simply used a bit of copper piping and some jubilee clips to join the two pipes, but make sure they are out the way of the turbo. Refill and bleed the cooling system. Then check there are no leaks from the joined matrix pipes, especially when it's hot and at higher revs, re-check the water level and refill if neccessary. It might also be an idea to clean up the water from the carpet if you havn't allready so you can easily see if water is still coming into the car.

Moment of truth, take it for a run or run it for as long as it took for you to loose water before. Still loosing water? If you are then that's another problem. If you have not lost water from your tank, congratualtions! You can still use your car, but have the looming job of changing the matrix.

The job itself - Removing the facia

One of the very first tips I can give you is, leave plenty of time. I made this mistake thinking I could start it at about 3pm and finish it before it got dark (8pm at the time). And all this the day before going to Santa Pod. I had to get up at 6 the next morning and put it all back together having not changed the matrix. The next time I completed the job in about 10 hours. I'm sure it can be done alot quicker but I like to take my time.

The reason this job is so horrible is the matrix sits in its heater box under the facia. You can see the damn thing when you remove the centre console, but the heater box needs to slide forward to allow the matrix connections to clear the bulkhead. FOUR cm GAP RENAULT! THAT'S ALL IT NEEDED! Because of this the whole facia needs to be removed. I have heard of someone who managed to bend the facia back to get access, but this is probably just as hard in the end. Removing the facia also gives you a nice opportunity to do any re-wiring, or adding switches etc.

First thing, get prepared. You are going to have lots of screws, all different sizes. First time I tried this job, I had screws floating about everywhere and had to put them back by memory. I then had the customary 2 or 3 screws left over at the end. Not the next time! I got a tub, a pen, and some post-it notes. Everytime I took something off the car, I pushed the screws into a post-it note folded it over and wrote on exactly what they were from. I saved so much time and effort doing this, and had none left over at the end. Result! Depending on how confident you are you could also lable any connections that you remove from behind the facia.

You will need a few sizes of torx keys, I don't know the exact sizes. You will also need a socket for the steering wheel nut, 19mm I think. Various screwdrivers and prody things are also useful. You will need a new heater matrix obviously. I can't remember what Renault quoted me, something like £80 - £90 or something as silly. I managed to pick one up under half the price localy.

1. Disconnect the battery negative.

2. If you havn't already disconnected the matrix from the pipes you need to drain the system and remove the pipes, located on the bulkhead behind the turbo.

https://www.rtoc.org/articles/i/matrix/smtrxpps.jpg

3. Remove the steering wheel: The Haynes manual notes it later in the process, but it's just getting in the way. Remove the centre cover, and find a socket that will fit the nut. From memory I think it's 19mm. If that's wrong, please let me know.

MAKE SURE the steering wheel lock isn't on as you may break it when removing the nut. Mine was very tight and I had to put it on full lock to get it to budge. I'd recommend getting someone to hold the wheel perhaps as I don't know the effect of putting lots of pressure against full lock? With the nut removed, you need to mark up the position of the column in relation to the wheel (so when you put it back on it's straight). Then withdraw the wheel from the column. The splines on this often obtain a good grip so you might need to tap/bang/severly hit the wheel from underneath to free it. It's also recommended to refit the nut a couple of turns so it doesn't come up of the column and cause any damage.

4. Remove the instrument panel: Take off the sun visor at the top, then undo the two torx screws, pull out the top of the panel while gently leavering the bottom of it and it should pop out. Disconnect the multiplugs and boost gauge hose. Also a good time to replace blown bulbs.

5. Remove the ashtray: pull ashtray out and remove two screws at the bottom, then disconnect the lighter wiring. Then remove the clock (or boost gauge?)

6. Remove the centre console. Take out your precious head unit. Prise off the gear lever gaiter and lift it up. Remove the two screws underneath that secure the centre console. Remove the two screws at the back of the console, both sides, near the vents. lift up the window and door lock controls and unplug them. Lifting the console push the gaiter through it and remove it from the car.

7. Remove the choke control: To get more play in the cable, it might be helpfull to unclip the choke cable from the carb with a screw driver. Remove the screw at the top of the choke control and pull the whole unit out. Remove the instrument light wire and the choke cable.

8. Unclip the heater controls from the facia. there is no need to disconnect anything from the back of it. There are four clips, two top, two bottom. Unclip them with a small screwdriver or similar while pushing the controls into the facia. There may not be enough room at this stage. Mine kept clipping back in place. So I had to unclip it again when the facia was pulled forward enough. You should take care as the facia in this area is very weak and flimsy.

9. Remove the upper trim panels on both sides of the facia (The panels that run up the side of the window and behind the grab rail (Jesus bar)) After removing the bar, there are two screws lower down the panel under the little button covers that need prising off. The Haynes manual says to remove the lower panels that run under the doors. I didn't remove these, however I think the facia may clip in behind them and you need to check they don't hinder removing the facia. Remove the long plastic air vents along the top of the facia.

10. Remove the steering column shroud: Three screws, two lower and one just under the steering column.

11. Remove the screws that connect the facia to the steering column or surrounding area, under the instrument panel. Two or Three I think?

https://www.rtoc.org/articles/i/matrix/clmnscrs.JPG

12. Remove all of the facia switches: fog lights, rear wiper, screen heater, blanking panels, etc. The multiplugs are keyed so should only go back one way.

13. Remove the screws on the indicator/light and wiper/washer arms. I can't quite remember if these can be disconnected from the wiring or not. Certainly with the indicator arm I managed to push it through the facia.

14. Remove the lower facia screws: these are in the area under the ashtray where the top of the centre console clips in, two I think, maybe more.

15. Remove the fuse box: Undo the screws holding the fuse box cover (lower part of the cover) and remove it. The fuse box doesn't need to be disconnected from the wiring, just from the bracket on the facia. I think there are four screws holding the fuse box in place, the two at the front are easy. But the two at the back if still present will have you feeling blind with legs/arms/head hanging out of the door. I never actually replaced these the first time I attempted the job, as you just can't see or feel exactly where they should be put back. You might have better luck, but it was the least of my worries. You can then let the fuse box just hang down.

With all this removed you're probably wishing you had never started. Your interior will be looking something like this:

https://www.rtoc.org/articles/i/matrix/smint1.JPG

You should now disconnect any more wiring that you have left, i.e. immobilisors and stuff.

16. Unclip the facia: there are clips at the right and left sides of the facia that you should be able to unclip by lifting each side of the facia. There are then four clips. These are located under the long air vent holes at the top of the facia. You need to lever something in there to prise them off. I used a part of some mole grips. Be careful not to damage the facia though.

https://www.rtoc.org/articles/i/matrix/clips.JPG

17. Remove the heater tubes that channel the air to the vents. These will go from the heater box in the middle to the vents at the sides. You can reach these from under the facia or through any gap you can find. They might also have cable ties around them holding the wiring looms and these need to be cut. This part might need to be done after the next if you don't have enough room.

18. You now need to work the facia forward. Keep checking none of your switch cables or control arms are in the way. It will probably still feel quite stuck, I know mine did. The wiring looms all run behind the facia and should be cliped to the facia via lots of plastic green clips. I had clips at the top of the instrument panel area running all the way along to the passenger side of the car. They might need quite alot of pressure to get off. If you can pull the facia far enough forward you should be able to get a hand then arm in through the various holes and gaps that are now present in your interior. I managed to drop the left side and pull it out far enough to remove the clips.

https://www.rtoc.org/articles/i/matrix/smint2.JPGhttps://www.rtoc.org/articles/i/matrix/smgrnclp.JPG

Once you have all these clips undone. With a little persuation you should now be able to remove facia from the car.

You will now be looking at something similar to this:

https://www.rtoc.org/articles/i/matrix/smint3.JPG

The matrix is indicated with the arrow.

19. In the engine bay where the pipes attached to the matrix there is a metal surround and rubber block. I don't think these need to be removed, but it may make it easy for the heater box to be pulled out in the next step.

20. You will now have easy access to the heater box inside the car. The casing is attached to the bulkhead. You need to undo these screws and pull the box forward until the pipe connections on the matrix are clear of the bulkhead. Undo the plastic clips securing the matrix in place (four I think) and slide the matrix out of the casing, and so leaving it looking like this:

https://www.rtoc.org/articles/i/matrix/smbox.JPG

You will be forgiven if you're now in a state of tears/shock/rage/all of the above. You may also be wondering just how it's all going back together! Don't worry I will cover a little of putting it back together, but most of it will be a Haynes style 'Refitting is a reversal of removal' as, well, it is.

If you are feeling especially wound up, now might be a good time to undertake step 25.

21. The new matrix should have came with a long strip of foam. This should be put around the outer edge of the matrix. I think it's just to protect the vanes when you push it into the heater box. Simply slide the new one in and into it's clips.

Reffiting the facia

22. So you're just over half way there, in need of a pint or 5, and probably feeling horrible. After putting back the heater box it's time to try and get the facia back. The best way I found was to get someone to help hold one side for you as you are moving it about. I hooked it over the steering column and basically started putting the green clips back, and moved all the wiring looms, cables, switches etc roughly into place. Start pulling things through the right gaps, i.e indicator arms, instrument panel multi plugs, fuse box and cables, etc, etc. Once most of the wiring is roughly in place it shouldn't be too hard to start pushing the facia back into it's clips. It's just a case of moving things out of the way from behind the facia until it moves back far enough.

23. Now just follow the steps in reverse, refit the water pipes in the engine bay, then refill and bleed the system.

NOTE: I can't quite remember when I put the heater tubes back in place. I think the drivers side one may go in after it's all back in place. Although it might be best to do it as soon as the top facia clips are in. You will probably have trouble moving the wiring looms into place though. Just keep a check that the heater tubes are all joined properly, as mine kept coming apart.

24. Once it's all back together and you're thinking never again, you might be faced with a few electrical problems, so check absoulutely everything. The first time I attempted this task, my immobilisor stopped working and I couldn't start the car. This turned out to be a dodgy earth. Then I noticed my brake lights weren't working. For some reason the switch on the pedal had moved.

The second time I completed this task the car started first time. Having checked all the lights and electrics were ok, I was feeling quite good. The next day after using the car I tried to lock it. My alarm sounded but I noticed the door pins did not move. AH! They moved when I opened it but wouldn't even twitch when trying to lock it. I tracked this back to some broken connectors under the centre console.

JOB DONE!

Now onto the best bit.

25. FINAL STEP: Destroying the old heater matrix. It's caused you all this hassle and frustration, it seems only fair that you show it the error of its ways:

https://www.rtoc.org/articles/i/matrix/smmatrx1.JPGhttps://www.rtoc.org/articles/i/matrix/smmatrx2.JPG

You can see the rust marks where the leak was, doesn't look much.

https://www.rtoc.org/articles/i/matrix/smmatrx3.JPGhttps://www.rtoc.org/articles/i/matrix/smmatrx4.JPG

https://www.rtoc.org/articles/i/matrix/smmatrx5.JPG

If I have missed anything, or you have any questions, get in touch, I'll be glad to help. Happy matrix hunting! Gary Broughton. Email: garybro@btinternet.com
Disclaimer: This information is only a guide. I cannot be held responsible for any damage caused by following it's contents. Just in case! :-)
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