Fitting AC to a 16V

[krekov]

Hi,
I've come across a bargain BX Pallas, last production year. It has AC, supposedly working.
It has the 1.8 turbo diesel, and I'd like to swap the AC from it into my 16 valve.

Is the 1.8td system more or less compatible with 16 valvers? Like, will everything fit?

Making custom mounting brackets or drilling some mounting holes aren't issues, I'm asking about more serious possible problems.
Also, I wasn't able to find any closer pictures of the engine bay of a 16V with AC, I'd really appreciate it if anyone could post some if they have them, I'd like to see how the original system was mounted.

[white exec]

AC was fitted to the 16v, but one fairly major consideration is whether your 16v has the diecast aluminium sump, with the four-bolt lugs for the Sanden compressor. If it doesn't, you might have to acquire a suitable sump, or ??? transplant your diesel one, if it will fit. DIY brackets for the compressor would not be a good idea.

Someone here must have retro-fitted AC to a 16v, I guess.

[RobC]

I’m fairly sure it’s something Vanny has done?

The diesel A/C wiring loom will certainly need some amending when transferring to a 16v- eg at wide open throttle the compressor is cut on the 16v. But I expect the wiring will be the least of your problems…

[krekov]

Well, I don't doubt this will be a time-consuming task, but I thought I could do it since the interior is soon be taken to bits, including a dash swap (severely cracked in mine).

I have easy access to a car AC specialist so I think he'll be of great help on typical fitment stuff, but I'd love to get more info on the BX specific electrical side, could you expand on those electrical differences between a diesel and 16V?

[RobC]

I think Vanny has the 16v A/C wiring diagrams?

He’ll be along in a minute I’m sure

[white exec]

As well as the sum-up thread on AC (which you've likely already read)
viewtopic.php?p=261690#p261690
these are a few pages I found useful...
.

The main EWD comes from Vanny's site.

[white exec]

...and some Citroen R12 to R134A conversion instructions for the BX:
.

[David]

I've put A/C in my 1.9 N/A diesel. Although it's not quite the same as a 16V, I can give a few pointers.

Everything *should* fit, but if your car's shell wasn't made for A/C then you will need to do some modifications.

Firstly, you'll need the holes in the bulkhead, where the A/C pipes pass through, just above the gearbox & the recirculation flap holes, just next to the windscreen washer bottles. If the holes are already there, then it will be a LOT easier. If not, then you'll need the dash out of the way in order to measure & cut out all the holes.

Secondly, you NEED the 2 fan setup. Again, if your car isn't made for 2 fans, then you'll need to weld some mounting points on for the 2nd fan & do some wiring modifications. If you do some searching on this forum, the wiring has been mentioned before, with posted wiring diagrams. I made my own wiring harnesses that work differently to any setup that the BX originally used, but it was easier for what I already had installed in the car. Remember that the fans work in conjunction with the A/C; they're not just for engine cooling.

Thirdly, I had problems when I changed the sump. It bumped into the flywheel so I couldn't fit it without either changing the flywheel or cutting some metal off the flywheel, although I assume that if you've got a 16V, then you might not even need to change the sump as it should already have the mounting points present for the compressor, you'll just need to add the mounting bushes inside the sump's mounting holes. (It'll make sense when you look at them together). Beyond that, it should just bolt together.

You'll need to drive the compressor off one of the fan belts. I think that it's the alternator belt, but I can't be certain as I've not seen a working 16V A/C system. Vanny would be the best person to ask here.

As for the wiring, there are loads of ways of wiring it up. Personally I wouldn't strictly follow the original wiring for a petrol model as I think that it just makes things more complicated than they need to be.

You'll then need to convert it to R134A. Again this has been covered in great detail on this forum. I had problems with my original compressor, and in the end I fitted a new one from a Lamborghini Diablo, which was already converted & fitted perfectly on my BX.

Make sure that you replace the dryer & all the O rings before you try to get it re-commissioned.

Hope that helps.

[krekov]

Hey, thanks for all the helpful replies and diagrams.

I bought that Pallas and have been enjoying it for 3 days now, and I've decided that I won't be messing with it. It's in what I'd consider immaculate condition, apart from some typical BX rust (no holes though). I just think getting the AC out of it would be a waste.

So, I've saved all of the information provided here and some other topics and it looks like I might get back to it once I find a worse BX with aircon, or install a custom system.

For now, I'll be enjoying two BXs and one with AC for hot days.

[white exec]

I'm glad you came to that decision. There's a lot of work in transplanting a system, and a shame to pull it all out of an otherwise decent car with it all factory installed.

When I was looking for a diesel with AC a year ago, I found less than a handful in Spain. One was rubbish, one (a full day's drive away) was ok, but being sold by a dodgy dealer, and the third would never answer calls or messages. Gave up on Spain, and turned attention to France, where there were no fewer than 80 diesel BX's for sale on Leboncoin, and around ten or so with AC. Found our 19D Millesime near Marseille.

My guess is that AC was a fairly expensive option for this essentially low-cost car, and so many buyers, not least in northern Europe, just didn't bother. AC did get included on some of the phase-out 'special editions' towards the end, which is where ours fits in.

As LHD presumably won't be a problem for you, you might find looking at France worthwhile. Leboncoin is a good site.

[krekov]

I did look in France and Portugal, but the prices are quite prohibitive considering additional import costs, and this Pallas cost me only 1000 pounds (converted), with 2 sets of fresh 2019 tires at that.

You're right in that AC must've been very expensive, the way it's done in the BX seems kind of unusual to me. It certainly complicates an otherwise simple car a lot.

Also, I've found that AC is predominantly found on diesels, and my theory is that it's due to how taxing the BX system is.
Engaging it even on a turbodiesel feels like engaging an extra brake and the car feels significantly down on power.
I can't imagine how bad it must've been on petrol 1.6 or 1.9s, or a 16V which has basically no torque or power on lower RPM.

[white exec]

Agree with you about the loss of available power when the AC is switched on.
Am getting in the habit of actually switching the AC off when needing to climb a seriously steep hill - to avoid having to drop into 1st gear. I remain amazed at just how much power the Sanden compressor mops up - and mine is a brand new one.

The (16v) petrols seem to have an "idle up" solenoid, judging by the circuit diagram, presumably to prevent idle speed collapsing. The diesels don't have this, and on ours an idle speed of around 850-900rpm with AC off reduces unacceptably when AC is switched on.

I intend to get round this by adding a PWM-driven solenoid to the fuel pump, to perform the same idle-speed pull on the idle lever that the waxstat-coldstart does. Have tried moving the lever (a pull on the cable by hand) a few times with a warm engine, and AC on, and the idle speed picks up to something sensible (around 900rpm). The bits to do this have arrived, so will try it out soon.

ECU controlled injection systems have the edge on this sort of thing, with the XM 2.5TD, for example, automatically maintaining idle speed, irrespective of the load placed on the engine at idle. Within reason, you can actually pull away in low gear just by gently raising the clutch, and letting the ECU maintain engine speed.

I'm unsure whether the EFI ECU of the 16v can do this sort of thing.

[Vanny]

The 16v, both Ph1 and Ph2 have a specific ECU calibration that manages the idle up and WOT cut of the compressor. Good luck finding one. The wiring is simple enough to add.

But the impossible part is the idler pulley. They simply do not exist, and I haven't yet come up with a reliable solution. The picture of the belt setup above is not right for the valver, not to say it won't work.

[white exec]

Vanny, Not quite sure which tensioning pulley is the problem finding, but Parts list 6453 E0 for the 16v AC system.
NFP, not on Mister Auto, but four choices on Autodoc.
Diam = 85, w = 23, and on a similar double-ended bolt to the diesel.

The larger diameter of the pulley might be because of engine layout, or maybe to keep its revs down for the much higher-revving engine. Looks as if it is retained on its shaft by an M8 nut+washer, instead of being M12 threaded-on as per the diesel.

Post a VIN if this isn't the bit.

[Vanny]

That part number appears to give an idler, not the tensioner.

The tensioner has an offset mounting hole.

The bolt on the 16v is double ended, but M8 ish in the block and M10 through the tensioner, hence they're pretty much all snapped.