Grey/Green and Grey/White. I have a feeling they are thicker than the others too.

Exactly like an air source heat pump except rather than generating 55-60 degrees C and trying to use that to heat water to be pumped around radiators, it blows that out as hot air the same as a fan heater so has a much greater affect on room temperature. That is when it is heating of course, when cooling that hot air is blown outside and the cold side is in the house. I've just got in from installing one now. When doing the commissioning you run it first flat out cooling and check the interior and exterior temperatures, then do the same with it on maximum heating. When cooling I was getting air at 2.1 degrees being blown into the room and the outside unit was running at 26.8, only marginally above ambient. When on flat out heating the indoor unit was blowing air out at 61.3 degrees while the outdoor unit was down to 16.1. Not bad when you consider it was only drawing 550W of power to do that.

The other difference between AC and an air source heat pump is the Government will give you a grant and reduced VAT on an air source heat pump but bugger all on AC as the cooling aspect means you are getting a further benefit and not just replacing a perfectly adequate (and cheap) gas boiler with something horrendously expensive and not as good.

Not when it is £60 for insufficient refrigerant for a P38 and you still need to buy the hose on top https://www.halfords.com/motoring/engine-oils-and-fluids/air-con/ac-pro-auto-air-conditioning-recharge---gas-r134a-264627.html.

I've got a couple of mates that both do mobile AC servicing at £55 a time. With the weather we've been having they've both been flat out and booked up solid for the next couple of weeks.

I don't think anyone without the kit will have done the job when you can take the car in and get it tested for leaks and refilled for £50 or thereabouts. It isn't something that many people here will attempt.

No, it doesn't go through the multiway connectors that suffer from water ingress, so you can rule that out. If it has been intermittent, I would suspect the brushes in the motor itself.

Yes, you can. There's two wires, power one way round makes it go up, reverse them and it goes down. The reason I asked about the locks and mirrors is that the BeCM sends a data signal to the door outstation and tells it to send power to wherever it is needed. if it was a problem with the outstation, then nothing would work on that door.

Changed the front diff. Coming back from Paris last week I noticed a strange noise and what can best be described as a tingling through the steering wheel at 80 mph on a neutral throttle. It wasn't there under power or on the over run, only when cruising. Figured I should really do something about it as I'm driving to southern Spain at the end of the week. So, last Monday, I phoned Ashcrofts to be told there was a 3 week lead time so went for the second option of secondhand and called in at my local source of used bits, Avenger 4x4. They didn't have any as they sell all their diffs to a company in Halifax call Beaumont 4x4 gearboxes so called them. Yes they could have a rebuilt front diff built up for me by Wednesday at £35 cheaper than Ashcroft. They called me on Wednesday to say it was all ready and they wanted paying before they would ship it. I mentioned that I've been involved with P38s for 12 years and had never heard of them. Apparently they haven't advertised to end users but supply a lot of the specialist trade.

Anyway, Thursday morning a man staggers up my driveway with a very heavy cardboard box containing a spotlessly clean, shrinkwrapped front diff. As most of you will know, since retiring from the day job I've been installing domestic air conditioning systems and for some unknown reason, I have been particularly in demand just recently so today was the first day I've had free.

We all know that RAVE has extra steps that aren't really necessary but when something hasn't been taken apart for quite a few years, the shortcuts wouldn't work so followed the book. Took almost 5 hours to get both front driveshafts out,although surprisingly both ABS sensors came out easily enough (I was half expecting to have to drive to Avenger with the ABS light showing to pick up at least one replacement sensor) and be ready to drop the old diff out. Old one out and with Dina driving the jack while I guided the new one into place, it went in. Bolted it up and started putting everything else back together. As I was no longer fighting bolts that were last touched 23 years ago and hubs that hadn't moved in the same length of time, putting it back together only took an hour or so. Did the same mod on the front of the propshaft as I'd done on the back end and replaced the hex head bolts with Allen bolts, filled the axle with fresh oil and took it out for a quick blast up the A1(M). No noise, no vibration, just perfectly smooth all the way up to 90 mph. I think I can call that a success. Just got to give it a service now before Friday.

Before putting anything in, you need to vac the system to get rid of the remaining Nitrogen and any air. That will draw the refrigerant in. To add the oil separately, you need the proper kit, so if you can buy R134a with the oil added, then use that.

Switchpack talks to the BeCM which in turn talks to the door outstation which supplies power to the window motor. Your best bet is going to be to follow the diagram in the ETM. Does everything else on the same door work, locks and mirrors?

There isn't an option to tell the BeCM whether they are fitted or not, but you should be able to control them from it under the Outputs menu. This assumes you have a high line BeCM which will have the relevant bits in it to drive them, if the car is an early, low spec, one it might have a low line BeCM which won't have the required circuitry to supply them with power. I'd start by seeing if you have power to the seats.

Not sure if the wire colours will be the same but on the P38 you've got a White/Orange on pin 1 which is a power feed straight from the fuel pump relay and a White/Blue which goes to the fuel pump through the contact in the inertia switch on pin 3. The contact is a changeover so under normal operation these two pins are connected together so power from the fuel pump relay goes directly to the fuel pump. The third wire on pin 2 (a White/Purple) goes to the BeCM to tell it if the switch has operated. Under normal circumstances, this is open circuit but on impact, the changeover contact connects it to the fuel pump. So it disconnects the power and supplies the BeCM with a ground via the fuel pump.

davew wrote:

(The 'high pressure' side originates from the compressor (as gas) which reduces through the Condenser/fan as it cools (to liquid) but if there is a "divide" per se that could be considered the Expansion Valve... and it is then the Liquid/Gas transition in the Evaporator that produces the cooling - if that helps..).

Wrong way round. The compressor sucks in gas and it turns to liquid under pressure and gets hot in the condenser, which is why the condenser has cooling fans. The liquid then goes through the expansion valve where it boils, turns into a vapour and draws heat (to use the correct term) and gets cold. Same as using a lot out of a Calor gas cylinder when the liquid turns to a vapour and the cylinder gets cold, sometimes cold enough for condensation, if not ice, to form on the outside. The vapour passes through the evaporator (not strictly correct terminology as it evaporates at the expansion valve) drawing more heat from the surrounding air giving the the cold. That vapour then goes through the compressor and the cycle starts again. The low pressure side is where the refrigerant is a vapour and the high pressure side is where it is a liquid.

As to why one side will hold a vacuum and the other side won't, I've no idea as it is a closed circuit. If doing a pressure or vacuum test, it shouldn't matter which port you use because of that. The only time you can have problems is if there has been a leak in the past which someone has tried to fix with a leak sealer and it has sealed something that shouldn't be sealed. But if everything is new, that is pretty unlikely. The domestic systems I am installing only have one port which on the low side but as they are reversible to heat as well as cool (the compressor can reverse so the condenser becomes the evaporator and vice versa), when heating that port becomes the high side.

It's obviously got enough gas in to close the pressure switch which is in series with the compressor clutch, but not enough to give you noticeably colder air. If you poke the AC Off button so it doesn't try to engage the clutch, set it at Lo and stick a thermometer in one of the vents with the engine running, you'll measure the temperature of the ambient air being drawn through the system. Then poke the button again so the compressor engages and watch the thermometer, chances are you'll see a small drop in temperature which will confirm a low charge.

A pressure test is more reliable than a vacuum test, the vacuum is to draw out everything in the system before filling it. I've just got in from installing a domestic system so have been testing at 43 bar as they run at a much higher pressure than an automotive system. If there's a leak, that will soon find it......

A mate has a workshop doing routine servicing, MoT failures and stuff like that. No end of times he gets customers coming in to have work put right that has been done by Halfords. They should really stick to pushbikes...

I did the full FGas course so I can install domestic and commercial air con systems (and for some unknown reason have been very popular in the last few days) but took the automotive exam at the same time so am qualified to do that too. To do it properly you use a recovery machine to remove any remaining refrigerant, then pressurise with Nitrogen, leave for 30 minutes to ensure the pressure doesn't drop due to any leaks, at the end of that time use a vacuum pump to remove the Nitrogen and any remaining air that may have been in the system, before refilling with the correct quantity of refrigerant.

The likes of KwikFit and Halfords use an automated machine (that way their staff don't need to be sent on a training course and pass a City and Guilds exam). It recovers any remaining refrigerant, skips the pressure test phase and goes straight to the vac stage. As long as the system holds a vacuum, it assumes no leaks then puts refrigerant in but has to be programmed before the start with how much. Some need it entering as a figure in grams, with others you tell it what car and it uses a look-up table to set the amount. However, if you ignore that setting it uses a default quantity of (usually) 600 grams. Considering a GEMS needs 1250, a Thor 1380 and a diesel 1100, you get a half filled system which will work but not very well or for very long. Easy way to check is to put it on Lo and shove a thermometer in the vent. If it goes down to 5 degrees C or lower, it's working as it should (out of interest, I checked mine the other day and was getting 3.9 degeres with an ambient of 29 degrees). If it can't achieve that, you've been given a short fill.

The clutch is on the front of the AC compressor. You've got the bit the belt goes round that spins freely and behind it is the actual drive to the compressor. The clutch is electromagnetic and pulls in against a spring so when it engages both parts spin and not just the bit on the front. All you do is tap it to give it a hand to pull in.

We had a big bloke called Rob who weighed exactly 100kg, so a Rob became a unit of weight. I weighed 0.7 Robs and all our other kit was marked in Robs......

If KwikFit did it, take it back and tell them it has stopped. They should pressure test it for you. Presumably the compressor clutch isn't engaging? That can be a result of the air gap being too big and usually means it will engage when the temperature is warm but it doesn't when the weather is hot when you need it most. Set the AC on Lo which will cause the HEVAC to attempt to engage the clutch and, assuming you can get to it easily on a diesel, tap the clutch with a screwdriver handle. If it engages then, the clutch needs a shim removing from behind it to get the gap back to where it should be (between 16 and 30 thou).

You can very briefly press in one of the valves but be careful or you'll get a face full of refrigerant and PAG oil if it does have pressure in it (this is also illegal as you are releasing fluorinated gases into the atmosphere and contributing to global warming). If you've ever used one of the self fill cans, they often have a gauge in the hose and will have the correct fitting to go on the port. R134a systems are pressure tested to 10 bar (around 145psi) and you should really be using Oxygen Free Nitrogen and then a vacuum pump to get it all out again. Compressed air preferably dry, can be used as long as you vac it out immediately you've finished the test. If you have lost the refrigerant, the most likely leak point on a P38 is the top left (looking at it from the front) corner of the condenser where it has a piece of foam on it. It has almost certainly had leak detecting fluid put in it at some point in the past so you will see a green stain which will glow under UV light.

I got deeply involved in axle weights and gross vehicle weights when I was still working. As all the vehicles were fitted with racking and storage cupboards built in, along with a pair of huge leisure batteries with associated electronics to control them, one of the vehicles was sitting a bit low when loaded with some other specialist equipment and two people. So much so, it was spotted on a vehicle check and put on a weighbridge. Only to find that without the passenger it was just under the gross weight but as soon as he got in, it was over.......

I was tasked with getting the weight down and by removing one leisure battery, I saved 31kg immediately. After attacking some of the racking with an angle grinder and dumping some of the other useless stuff (like the jack, wheelbrace and spare wheel, as we weren't allowed to use them anyway and were supposed to just call out the AA), I managed to lop almost 200 kg off the weight. We even had a chart in the office of how much each of us weighed so we could match who could travel together too.

Re the EAS, do the sums. Unloaded each rear spring is supporting around 500kg and at that the pressure in the rear springs is roughly 75 psi. Increasing the load to maximum results in each spring supporting 920kg so the pressure in the springs will increase to around 140 psi.

However, your original weights are wrong. The EEC kerb weight (car+full tank of fuel+75kg driver), for a 4.6 is 2220 kg and the gross vehicle weight is 2780 kg, so the maximum load is actually 560 kg (2780-2220). What I find interesting is that the EEC kerb weight for a 4.0 litre auto is 2100 kg, yet the kerb weight for a 4.6 auto, is 2220 kg, a difference of 120 kg. Yet the difference between the two versions is merely a different crankshaft and con rods, which I would assume would weigh around the same and a marginally larger gearbox which, having humped both around just recently, doesn't weigh that much more. No more than 10 kg, if that, and the additional 1.3 litres of ATF in the gearbox isn't going to make that much difference either.

It can, as long as your air springs are decent. I've carried over half a tonne in the car and 3.5 tonnes on a trailer behind it. The nice thing about the EAS is that the arse doesn't sag when it's loaded so unlikely to attract the attention of Mr Plod.