Retro fitting AC in a MK3 sport

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“Don’t bother”, “buy another car with AC fitted”, “it’s too much work”, “it’ll cost too much”

 

That’s what people said I should do when I asked about retro fitting an AC system to an old MK3. Well it may be old but it’s mine and I have spent ages getting it the way I want so I either sweat like pig and put up with it or I must defy the neigh sayers and plod on regardless. 

 

I have chosen to plod on regardless!

Parts I have ordered so far:

 

Heater box with AC evaporator. Ebay ÂŁ50 arrived Tuesday

New condenser. Ebay ÂŁ99.01

Compressor Ebay ÂŁ10 +p&p

Long fixed pipe. Ebay ÂŁ30 from Germany +ÂŁ14 p&p. (a right hand drive donor if you are wondering) arriving Thursday

2 flexi pipes. Ebay from Australia ÂŁ30 +ÂŁ20 p&P

AC control unit from a CC model ÂŁ17 from Ebay. Might have to go to USA for a manual one.

 

The basic plan is to fit all the bits from a factory install and hope to who ever is watching that the electrical side will play ball.

 

Day one.

According to accepted wisdom to change the heater box requires the removal of pretty much the whole interior of the car including the steering column and complete dash board with brace. I compiled all the relevant pages from the Haynes manual into a ring binder and went out to the garage. I am lucky enough to have a double garage but it’s still a bit tight with 2 motorbikes and the wife’s TT taking up a lot of the room. To make life easier should i need the extra room I jacked up the car and put it on skates. I can now move the car around as needed without the steering wheel.

I started with the easy bits and disconnected the battery. The Head unit, centre console and glove box were out in a jiffy, as were the instrument pod, the instrument and the panels surround the steering wheel. Now I am in the hands of the Haynes manual as I have never gone any further.  Side panels were coaxed off and so were the hazard switch and vent panels once I found where the screws were hidden. Next up was the steering column, the bit I was most fearful of. I followed the manual meticulously and was really struggling to understand how the indicator and wiper stalks were supposed to come off before the steering wheel. Turns out I am a muppet and missed the bit where it directs me to section 412, part 564 to remove the wheel. Wheel off, and then the countless connectors surrounding the column. Four bolts and the steering column flops out on to the floor. I left it there. The manual says to disconnect the pinch bolt and remove etc etc but I just needed it out of the way of the dash so flopped onto the floor was good enough.

Now it’s time to start disconnecting all the electrical bits attached to the dash. In no particular order:

DSC switch

Bonnet pull

Boot switch.

Airbag switch

Light leveller switch

Hazard light switch

Airbag connector

Little black box behind the right hand side of thes teering that I can’t figure out what it does.

The big connector with the lever to the left of the wheel.

The smaller yellow one, presumably the airbag again

The big connector behind the fusebox

The small connector behind the fuse box

The door connections

 

Before the dash can be removed the manual says to drain the coolant and disconnect the pipes into the heater. Sod that for a laugh, I’m not draining 6 litres of coolant indoors it’ll go everywhere just because I don’t want it to. I settle for disconnecting the two hoses and placing them high up so the water does not run out. On the heater I put two little fingers cut from a rubber glove over the metal snouts and sealed with a cable tie.

I undo the ten bolts that hold the dash board in the car and summon my son from the house to help lift it out. Of course there are a couple of connectors I’ve missed but out it comes.

Below is a picture of the inside with no dash.

https://imgur.com/a/fUc87vy

 

I carefully placed the dash assembly on a west ham quilt on the floor of the garage. If it’s good enough to help me catch some Zs on my break at work then it’s good enough for this. I photographed the new unit next to the assembly:

https://imgur.com/a/fUc87vy

Swapping them over was a simple affair  which included undoing and doing up of bolts.

Whilst the dash was out of the car I did some tidying up of the cabling for my dash cam and routed it away from the dab aerial. I also routed the dab aerial down the opposite flank to give myself the best chance of a clear signal. Time will tell.

Eldest son was summoned to help get the dash back in the car. He helped me lift it into the car, grunted a few syllables and then went back to shouting at people on his computer game.

As they say refit was the reverse of removal but easier. I connected all the electricals and bolted up the dash and the steering column to the car and then fitted all the plastics back where they belong.

Reconnected the heater matrix to the cooling system. That’s gonna need a good burping tomorrow.

Reconnected the battery and none of the airbags went off which was a good sign. Car started and the new heater assembly directs air as per the directions of the controller. When in test mode the AC controller now lights up the ac button when in feet and face mode where before it only did feet. Hopefully this means it’s talking to the temp sensor in the chiller unit ok.

Airbag and DSC lights were on. DSC was expected, airbag was not. My code reader does not support airbags so a manual investigation was carried out. I’d missed a couple of connectors. Off with the battery again for a few minutes and then reconnect the airbag wires. Battery back in, air bag light off. Phew. As i’m writing this I have remembered that I did not put the grub screw back in that holds the clock spring switch in place so that’s another job for the morning before a quick road test and burp. I know i have missed some other screws too as I have some left over screws and clips.

Total time spent 12 Hours. I may or may not start on the condenser tomorrow

1 Like
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Now this is impressive  well done for having the kahuna’s to attempt this conversion! A very well written and light hearted style. I await your next instalment. Certainly not something for the faint hearted.

Barrie

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Impressively crazy, look forward to the conclusion.

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Long solid pipe arrived today with a nice bend in it(so it would fit in the box). Have to work out a non destructive way to unbend it. Woke up this morning feeling like death so nothing too involved will happen today, a quick burp and a test drive might be it.

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That is some seriously impressive fettling, good luck with the rest of it… 

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Started to feel a little better this afternoon so after a trip to the dump with the mountain of cardboard and a tidy up of the garage  I set about fiddling with the car.

Rear anti roll bar bushes turned up so put them on the car. Simple job, no need to even jack up the car. 10 minutes.

Let the engine run a while to clear the air put of the cooling system and fill the heater matrix. Heater now works as it should.

Investigated the long pipe that arrived this morning. Placed it in front of the car. It’s very bent. Not the end of the world as it’s quite pliable but as I was hoping to use the shape of the pipe to indicate where things should go. Hey ho I’ll have to Sherlock any mystery positionings. The car already had clips fitted for the pipe to go across the back of the engine bay so after a bit of jiggery pokery and some subtle bending I had the union lined up in the evaporator and the pipe across the back of the bay in both clips. Turns out the rest of the pipe was somewhat bent too as with the pipe in place at one end the bit with the sensor on was two feet higher than everything else. More subtle bending brought that down a bit but then revealed that the suspension brace and the cable that runs along the washer bottle was in the way. Suspension brace off (four 12mm nuts so easily done) and some waggling and the pipe slots nicely into the clip that is on the side of the washer bottle and the sensor wire plugs in. Suspension brace back on and some more waggling to give some clearance to the brace and the ABS unit. Quick test drive to check for rattles and because I have not driven the thing for a couple of weeks so I just needed to get out in the car. No rattles. All good.

I have discovered that there are a couple of things that I have not yet obtained. 

The bracket that secures the pipe in to the heater box. Looks like it would be a piece of metal with two holes and two slots that pushes the flanges (i hope they are called that) of the two pipes into the heater box.

The connection between the condenser radiator and the  long metal pipe. From the position that my pipe is in it should be a reasonably short connection.

 

https://imgur.com/a/fUc87vy

 

https://imgur.com/rQuOrDA

 

https://imgur.com/ok6EzN9

 

https://imgur.com/TPeuKMh

 

If anyone would be willing to send me a photo of their AC components particularly the front near the washer bottle and the rear as it enters the heater I would be very grateful.

Time spent today approx 1 hour including reprogramming the stereo

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Just nipped down to the car, hope they show what you need 

Hope you’re feeling better now, I want to see this finished!  

Barrie

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That was exactly what I needed Barrie thank you. That first one also solved a mystery about a random bolt sticking out in that area. Looks like I need to knock up a bracket!

 

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Part two. The extra swearing edition.

 

All the parts have finally arrived. The two pipes from Australia were the last to arrive.

 

Preparation: Jack the car up nice and high. Remove the front bumper to give better access to the condenser mounting points. It’s the first time I have removed the bumper from an MX5 so there was a bit of hunting for the clips that need to be reomved. I unfastened all the clips I could find under the wheel arches and the three bolts on either side that hold the front wheel arch plastics and wiggled them off. More trial and error to remove the rest of the bumper. The screws on the inside of the wheel arch were initially elusive but I found them eventually, then all the bolts across the front of the bonnet opening were removed. A bit of head scratching then followed as to why the bumper would not budge. Then I remembered the clips on the front of the grill that hide a couple of bolts. Clips removed, bolts undone, fogs detached and the front bumper now sits in the back garden.

 

Condenser: The manual says that the power steering pipes need to be loosened to allow the condenser to slide into position in front of the rad. They are not kidding about this. Unfortunately the bolts that hold on my power steering coolers are rusted solid and or spinning freely with a rusted on nut on the inaccessible end. Not to be defeated I offered up the condenser in front of the radiator. It is supposed to slide down into lugs that are positioned on the front of the rad. With the steering pipes in position the top of the condenser can not get high enough for the tabs on the sides to slide in from the top. With a little bit of wiggling I managed to get one side in by prying the lugs open a little with a screwdriver whilst waggling the condenser up and down. Now with the left hand side4 of the condenser in place there was only a quarter of an inch of lug preventing the condenser from sliding in from the top. The condenser was too low. I retrieved a hacksaw blade from the bodge it box and gently hacked off the top 6mm from the lug and slid the condenser into place again with the help of a prying screwdriver.

Pipe from condenser to HI/Low pressure sensor. This was really frustrating at the time. It’s such a small length of pipe but it must have taken a good half an hour to cajole into position. This was probably not helped by the steering pipes being fixed solidly to car. It went into position eventually.

Compressor: This took the most time. Requiring the removal of the battery, battery tray, airbox, drive belt, idler pulley and PCM. Battery and airbox are relatively easy and were out in a jiffy. The PCM is a whole other pain in the rear because it was held in by security bolts. Oh good more drilling, I love drilling, I always get the drill to go right down the middle of the bolt and never ever ever drill it off centre and have to drill 3 or four more holes. 6 holes later I have the security bolts out, they will not be returning. I’m not entirely sure that security bolts were really necessary; do people really steal cars by replacing the PCM? Drive belt was easily removed with the help of a 14mm spanner on the tensioner pulley as was the idler pulley. Before the compressor could go in it needed to be refilled with 130ml of PAG ISO100 oil. Unfortunately euro car parts let me down with their same day delivery service so an overnight wait was involved before I could complete this part of the job. The use of an allen key on a cordless drill and a 100ml syringe I managed to get the compressor filled up again in about 5 minutes. I plugged the holes on the compressor with some blue roll and started to position it on the engine. The haynes manual does not quite convey what a pain in the rear this particular task would be. The compressor barely fits between a cooling pipe, the bottom of the PCM tray and the pullies on the front of the engine. The air was blue as skin was removed from various parts of my arm and hands and the blue roll kept escaping from the holes in the compressor. Eventually I lined up one of the holes and pegged it in place using a 100mm M8 bolt. More wiggling, more blue expletives and I managed to get it into a position where it did not foul anywhere and the holes lined up. M8 bolts of various lengths were placed into the four holes with extra washers where i felt the length of the bolt I had did not match the depth required.

Pipes: All the pipes were fitted with new O rings kindly donated by the garage near my house. Gently smeared with pag oil and secured into their respective holes with M6 bolts and in the case of the joint at the front an M6 flange nut joined in the fun. 

A new drive belt was fitted. AC cars need a longer belt (story of my life) which I had procured ready for the excitement. Battery box was returned to it’s rightful position and the PCM was refitted with a set of M6 bolts. Airbox went on with the customary “which way does the filter go in?” head scratchy moment. 

I took the car off the stands and started her up. No unusual noises detected. I left the front bumper off as it makes it easier to get to the probable leaky parts and drove to the friendly garage near my house. By near I mean 308ft so I was not too worried about not having the front bumper in place. It was only once I get there I realised that I had no front number plate!

 

I’ve left the car at the garage to be gassed up. Keep em crossed for me!

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Was thinking of doing that to my mk 3 when I drove down to the south of France but I chicken out so well do you very brave man
Can you do mine LOL ?? jon??

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Bugger.

 

The pipes are leaking. Solid pipe that goes into the condenser and upto the hi/low valve is leaking at the welded joint. Might have to get a hose made up.

 

No air con for me on the hottest weeked in August!

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Yep, I was possibly one of the people who advised you not to bother with this and if I didn’t, I owed it to you toSmile

This is the sort of thing I would do much against my own advice and spend way too much time polishing t*rds and getting a huge amount of satisfaction out of it.  

You are almost there - congratulations and I hope the recharge lasts for a long, long time.

Some hotter weather this weekend - be nice to test it. 

 

Shucks - just seen your last post!  

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Particularly annoying that the joint itself went rather than a bit of my plumbing. There is a local firm that thinks they can do me a flexi pipe. It will require the re-use of some of the ends but I think i can make the two lengths of solid pipe into one long piece and re-use the middle joint as the end. A flexi will certainly be easier to fit!

 

Of course it’s a bank holiday now so I will have to wait till Tuesday to get it sorted.

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Yes, provided any cast or complex joining parts are good, an aircon engineer will crimp or otherwise join rubber pipe replacing the damaged metal.

Quite a common scenario with the early Eunos cars where pipes fail or a condenser with differently orientated fittings used.

At least the leaks were spotted quickly. I would ask for my money back if it is the long pipe that the idiot seller bent to fit in the box. These things will usually accept one bend but likely to leak when you have to bend back.      

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I could but you wouldn’t like the cost! 

 

So far it’s cost me £120 in pipework, £50 for the matrix, £100 for the condenser, £20 for the compressor, £10 for compressor oil, £17 for a belt and £40 for the controls == £357 Gassing it up will be about £50 so £407 all in. I don’t know what the flexi pipe is going to cost yet but I’m hoping to get change from £500 total.

 

With labour I could probably get it done for you for about ÂŁ1000!

 

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Looks like I will stick with my ÂŁ30 double plug in fan LOL ?? cheers jon??

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Twas my fault I think. I think I was perhaps a little to easger when threading the pipe down past the radiator. It was the short pipe that let go, the long slightly bent one is fine, until I start cutting it up to make a new one that is 

 

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Tuesday 27th August 2019.

After looking at the long solid pipe and the short solid pipe it was clear to me that the end of the long pipe was the same as the bottom end of the short pipe. I took my two pipes over to Crimps Automotive in Takely and explained that I would like the long pipe extended with some flexi between the filler and the end fixing. After a short investigation the bloke there said he could probably do it but couldn’t be certain that it would seal. Twas a reasonable price so I told him to go ahead. 10 Minutes later I walk out with a nice long hose.

Fitting the hose was a matter of minutes as I’ve done it once or twice now. The flexi part is slightly too short but with a little coaxing I was able to get it tightened up. The other joints on the flexi were tightened up and off I trot to the local Mechanic [Smart Mechanics].

The machine stopped 17 minutes into in’t routine as it had found a &%$£%^& leak!

I told the bloke what had been done and we tightened up the flexi fittings a bit more, we had to remove the battery to get to one of them. Looks like I am a bit too tentative as he winds the nuts a good bit further than I did and going to the the trouble of putting ptfe tape on one of the joints (I’ve spent some time plumbing and have always been told that you can always tighten things a little more but once it’s over tight it’s had it). He starts the machine again.

A nervous 15 minutes later the machine makes a little sound and prints a success slip. Woo hoo!

Battery back in and give it a go.

Car starts up fine. with a trembling and very grubby finger I press the AC button. A squeal from the new compressor as the compressor clutch kicks in and the fan starts up. The engine revs rise to compensate for the extra load and shortly after some very cold air emerges from my vents.

 

I am so happy! I’m both proud and relieved that it has worked. I was really expecting something in the electrical side to put a spanner in the works but it works just like it had come out of the factory like it. I must commend Mazda for making this job as easy as it was, all the clips for the pipe work were there, all the connectors were present and the programming in the PCM was present and correct too. The bits that I took off and then had to replace all went back on with the minimum of “why do the holes not line up?” and of course using the same (or very very similar)  bolts for everything make choosing the correct bolt from a big box of bolts very easy.

 

So my advice to anyone else wanting to do this is. Yes it can be done, it’s not actually particularly tricky from a taking things apart and putting them together point of view but it does take a lot of time. I could cut a good couple of hours from the job by not removing some of the components from the dash that the manual stated needed removing like the vent panel, the Hazard switch and possibly the instrument panel too. Be extra careful with the solid pipework, they have been the only real snag on this job and it’s my own clumsy fault for man handling them in the way I did which cost me a lot of stress and a 3 very hot day wait.

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