Mystery air/con leaks on BXs?

Post your Cit/Peu/Ren air conditioning queries or advice.

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alan s
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Mystery air/con leaks on BXs?

Post by alan s » 03 Apr 2007, 23:44

I've posted this on another forum, but seeing as you guys are heading into the hotter weather, thought it might be of interest to you also.


Over the years, there have been a few BXs with non operational or marginal air/con.
The usual "I had it regassed a few weeks back but it only lasted a few days so the guy put some green dye in it and it was gone within 24 hours" has been heard many a time followed by us advising them to look at the T/X valve which always seemed to be a suspect and which in many ways, didn't really make sense when the exact same valve is commonly used in not only Cits but Pugs and even Mercs, yet they don't seem to have this "inherant problem"

Recently, I decided to look a bit closer at the air/con on my BX16V that has never worked as long as I have owned the car and whenever we have tried to do anything on it, either I didn't have the time to go through it properly or the equipment I needed wasn't available or my mate the fridgie was passing through and just called in and gave it a quick whack as he was passing. Again it would last only days, so this time I decided I'd do it right.
The T/X had already been replaced due to a nice oily stain in the vicinity of the TX, in fact it was dripping out of the bottom of the TX cover. Close inspection showed what was possibly the leak, but IMO, not conclusively. When pressure was applied to the compressor, it was noted that a leak was evident at the suction connection. New "O" rings made no difference but on closer inspection, it seems the hose may have ruptures/leaked internally and the pressure has built up between the inner and outer casings and caused the leak to appear at the crimped end near the elbow that connects to the compressor.
As a precaution, I removed the compressor and drained the many attempts' green dye from the sump of the compressor and stripped the head and valve plate off the compressor, washed, wiped and checked the valves and the plate for any signs of damage. It was all clear so I topped up the oil and refitted the compressor.
Removing the hose that ran from the firewall to the suction side was a right old job as it is fed through a small area between the battery carrier and the inner, fun, fun.
Upon inspection it was discovered that this hose has an aluminium fitting that connects to a brass one that has a piece of 1/2" copper tube set in the middle of it and this tube was damaged at some stage; factory or one of the Sydney meat vendors we're not certain, however it was impossible for it to seal properly. Added to this, it also had a weird looking "O" ring in it which was black plastic and tapered. I've never seen anything like it and neither has anyone else. It is also made of plastic not rubber as they all used to do in those days, so I replaced it with a neoprene one. When I removed a hose from a car we had here, lo & behold it has one also, so we think it may be that due to the position this hose is in, directly above the exhaust pipe, that perhaps this was Citroens way of compensating for the heat factor. It could be that the taper is to allow for the strange angle or simply because being made of a hard material they didn't think the plastic would seal if normal "O" ring shape or that it might flatten out and leak; either way, it doesn't work as this one appeared to be leaking also.
We then get to another car with a chronic leak and lo & behold, it's got one and it appears to have had a slow leak too! We based this diagnosis on the fact that both had the dreaded green dye running down the threads and in one case a guy who is a mate of the owner along with the owner did a very meticulous UV examination of this entire system and couldn't find a trace of any leak which IMO is easy to explain. The fittings are recessed back into the firewall to an extent and surrounded by insulation which is black. Located directly above the exhaust I'd reckon the dye either never made it to the outside or was simply soaked up behind the insulation. The oil inside around the TX is also explaine when you see that the connection to this hose is on a piece of 1/2" copper tube that is about 8" long and runs from the T/X (Eaton block valve) to the firewall, hence any loose or leaking threads could quite easily spray the gas/oil combination all over the TX giving the impression that the TX "Dunnit" when in effect it was the fitting, as a result, in changing the tX you remove the fittings so any tradesamn worth his salt replaces the "O" rings and in the process fixes the leak. They don't have to touch the firewall fitting but most would just run a spanner over the sytem and possibly seal off any slack that may have developped in that tapered "O" ring and bingo, a fully sealed system.......................and the TX valve? Well I wonder how many perfectly good TX valves have been sent to the scrap yard?
Like the Butler we've always blamed the TX and like the Butler, perhaps he didn't do it.
Handy info for anyone running out of ideas trying to get their BXs air con to work though.

Alan S