P38 late diesel Air Con condenser repair

Although there are hints about it on other threads; the last few P38 diesels in 2001 and 2002, for some unobvious reason, had a different condenser installed. It’s basically the same width and has the same fan unit but is shorter at the bottom. This short condenser is matched by an engine oil cooler that has brackets to mount the bottom of the condenser – so the oil cooler is also different in these models. See the pictures.

So if you have a leaky condenser Plan A would normally be fitting a new one. Unfortunately with these short ones, if you can find someone who doesn’t try to sell you the square type condenser that fits all the petrol P38’s and the earlier diesels, they quote you an astronomic price (that I wouldn’t pay anyway) and then can’t find one! It’s a pity as the normal square ones are readily available and not expensive.

Plan B for me was to try to get the condenser tested and repaired. I tried a couple of places but they wouldn’t even look at it – ‘as soon as we strike a torch on it - it collapses’. It sounded like they’ve had a bad experience and the aluminium is very thin and contaminated, not good for welding. I had to move onto phase 2 of Plan B – a DIY job. Before I go into that I did have a Plan C if necessary. It looks possible to install the earlier square type condenser if you’re prepared to cut away the aluminium brackets on the oil cooler and unscrew the aluminium drip tray (?) across the front of it. It looks like the feet to mount the bottom are still fitted on the chassis so it could go in. But the pipe connections are different and you’d have to do some jiggery-pokery there as well.

Finding the leak site was the first priority. Apart from being grubby it didn’t look too bad, not all white oxidised and crumbly. One of the connections is tapped 5/8UNF; fortunately this is almost identical to 3/8BSP a common pipe fitting size and I was able to make up a fitting with the centre of a tyre valve soldered into a 3/8BSP connection. Mine also had a loose nut and fibre washer but would probably work without these. This screwed in about 1 to 2 turns and with some Hydraulic Seal Loctite made a good seal with a connection that can be inflated with a tyre pump. The second connection is a little trickier. It’s a 15mm parallel hole sealed by an O ring. An O ring nipped between two ¼” washers by a nut and bolt does effectively seal onto the parallel sides of the hole – with some Loctite to help as well. See the pictures that illustrate this better. I’m very wary of testing things with pneumatic pressure; there can be a lot of energy released if it goes pop. I found out the hard way that the friction grip holding the O ring sealed plug in place would give way and it would shoot out at anything much above about 20psi – always keep it pointing away from you - so I limited myself to that pressure. I found that running the tyre pump off a battery charger – which isn’t really man enough - makes it run so slowly you can’t inadvertently over pressurise.

Pumping it up and dowsing it with soapy water showed up a leak coming from behind one of the top brackets. I was expecting to find a stone chip in one of the tubes but they looked OK. This bracket looked like it had three aluminium dot welds holding it to the header. Cutting through to remove the bracket didn’t release it and despite trying a careful hammer and chisel the remains of the bracket wouldn’t budge. I have the impression there’s some sort of a seal under the bracket and that this was leaking. Other bits and pieces on the condenser look like they have a dot weld to retain them but have an alternative seal – perhaps glued in place? My repair was to cut around the bracket, clean up the metal with a Dremel wire brush around its four edges and then let some Loctite hydraulic sealant soak into the gap, clean up again and apply an Araldite fillet over the edge of the bracket and the header sealing in the Loctite. No bubbles on testing again – success.

I had a plan for a damaged tube. The fins push back easily and by cutting the tube roughly at the leak site, filling up the ends with Araldite and rolling them back like squeezing a tube of glue or toothpaste should seal off both ends.

The condenser is mounted by two spikes on the bottom entering rubber grommeted holes in the brackets on the oil cooler. There are two bolted brackets at the top of the condenser onto the intercooler. I’ve cut away one of the top brackets but it still feels secure, a three point mounting is probably better to avoid twisting or fatiguing the condenser. Foam on the underside of the closing shut panel also retains the top of the condenser stopping it moving around.

It’s worked for me, it may help you.

Other bits and pieces I’ve discovered on this journey are;
The square type condenser part number STC 3679 or AWR1624 and Valeo 816885, core size 562mm x 551mm x 30mm is fitted to all petrol P38’s and diesels up to 2000 up to chassis YA447505. JRB000030 is also quoted but is obsolete and superseded by JRB000040. Dimensions of this is quoted as 547x548mm with top connector of 5/8UNF 18 and bottom as 3/4UNF 16.
I have not been able to find a part number of the shorter condenser but JRB000040 was on my fan/condenser unit, maybe this is more related to the universal fan unit rather than the condenser?
O ring size for the parallel hole on the short condenser;
Two used O rings (original green ones)
15.3mm OD x 10.6mm ID x 2.4mm chord
15.6mm OD x 11mm ID x 2.4mm chord
A new O ring from my standard boxed set – RO8
15.3mm OD x 10mm ID x 2.65mm chord

Great advice. I had the same problem. I changed the condenser pipes for the old thpe and retro fitted the large and older condenser.

Hi there. I have just joined the forum and I too have a 2001 p38 with the mega expensive Aircon condensor. £360 as opposed to £80 for the old style one. Could you please tell me what was involved in your conversion i.e. New to old style. I guess you need new pipes and somehow alter the oil cooler. Many thanks for any help. Kev.