Remove both centre console side panels (2 screws in each, if they are both still there), lever outwards at the back and slide down and back. Undo the 4 screws that hold the HEVAC in place, tilt it out at the top then pull. Black plug on the left side is the one to the blend motors.

The switch......

There's 3 blend motors, one for each side and one for air distribution so it sounds like you have one or more intermittent blend motor. Pulling the HEVAC out and giving the blend motor connector a dose of contact cleaner might work. When you first start the car the blend motors are driven from one end of their travel to the other to check for a feedback signal. If the HEVAC doesn't see that signal, it won't try to move that particular blend motor again, or at least not unless it passes the self test on the next start. With working blend motors but non-functioning AC, putting it on Lo will give you air at ambient temperature.

Yes, as Garvin says, the Grey/Black isn't the power supply, just a turn on signal for the amp which gets it's power from the door outstation. While doing away with the amps is an option, they incorporate a crossover so the signals to the bass speaker is split from the signals to the midrange and tweeter. So if doing away with them, then ideally you need to fit crossovers in their place.

First off it sounds as though you have the Mid line system and not the High line with amps in the doors and someone has fitted the HK tweeters with the logo on the covers (but not the HK bass and midrange units) and CD changer. Although Mid line didn't have the amps in the doors (mounted low down at the front of the door) and the head unit was wired directly to the speakers, but it also didn't have the CD changer, sub-woofer and steering wheel controls. My '96 HSE Ascot has the amps in the doors, CD changer in the boot, sub, steering wheel controls, HK logos on the tweeter housings and also on the door cards above the grille for the bass speaker. So you either have a Mid line spec that has had the extra bits added or a High line that has had the door amps removed (although I would have thought you would notice bodgery in the wiring to the speakers) or you simply haven't found them.

As someone else has already been in there you've no way of knowing what has been done to it so your best bet is going to be to go back to basics. Test from head unit to speaker by connecting a 9V battery across it and listening for the thump (or try connecting temporarily from head unit output to speaker). If you do have amps but haven't found them, they need power on the Grey/Black wire to turn them on.

Sloth wrote:

That said if you want to fly me out to you, I'll happily bring diagnostics and recovery/evac/recharge kit with me to diagnose and regas it once we find the problem. No charge, just cover my travel costs :P

It would be interesting to see what airport check in would make of a 10kg cylinder of R134a and an empty recovery cylinder too. I was once stopped from boarding a plane because I had a pair of gas shocks in my hand luggage. Then again I was also stopped once when my luggage tested positive for Semtex which turned out to be two dead Duracells in the remote for a satellite receiver I was taking over for a mate......

The '96 has been used mostly by my other half to carry building materials for a house we have been renovating. Tools in mine (the '98 ex-plod, now with 443,000 on the clock) and sheets of plasterboard, plywood, wall tiles, etc in that one. A lot more practical than her Merc SLK280 and quicker than two trips in mine.....

It depends what sort of a mechanic he is. Some are fully skilled parts swappers, the better ones will try to diagnose the problem first. However, with AC, virtually everyone will go for a regas first, providing that is done properly (recover, pressure test, vac out, refill with the correct amount of R134a). As far as sensors go that could be inhibiting it, you've got the aspirator (the cabin temperature sensor in the dash) but if that was to go open circuit it would detect a cabin temperature of -40 degrees C so wouldn't engage the AC compressor as it thinks it is cold already. You've got the heater core sensor which, again, if open circuit tells the HEVAC it is at -40 degrees C although I think that will only stop it from heating not cooling if the cabin sensor says it needs it. Then there is your suspect, the evaporator sensor which will shut it off if it is getting too cold and likely to freeze but it wouldn't prevent it engaging the compressor, it would engage, get very cold then disengage as the temperature gets low. But you need diagnostics to be able to see what the various sensors are reporting.

However, thinking it through, you've got an early car which drives the compressor clutch directly and not via a relay like the later Thor ones do. In the case of an early car, if it tries to engage the clutch and the pressure switch is open due to a lack of refrigerant, the HEVAC detects that it isn't drawing sufficient current so logs the fault, brings the book symbol on and doesn't try to engage it again until it is reset the next time you start the engine. So you would get a very brief flash of your LED the first time it tries to engage it then after that it won't try again. So the regas may just be all it needs.

When working correctly, one of the refrigerant lines should be too hot to touch while the other should be very cold and may even have condensation forming on it. If you can touch both then it isn't doing anything. However, even if low on refrigerant you would still get the signal from the HEVAC to engage the clutch, it just wouldn't get as far as the compressor due to the pressure switch. So it does sound as though something is stopping the HEVAC from engaging it. Ideally you need diagnostics that can show you what values the various other sensors are giving.

P1179 is listed as Maximum Negative AMFR Correction Fault which means the adaptive value for the MAF is as low as it will go so it has reached the maximum limit. Reset the adaptive values and then check the readings from the MAF. They should be 20 kg/hr plus or minus 3 kg/hr at idle speed and 61 kg/hr (again plus or minus 3 kg/hr) at 2,500 rpm. This is checked at sea level, engine fully warmed up, in Neutral and with all electrical loads off.

If they are outside of these specs, the ECU will add a correction factor to keep them in spec but it can only adjust by a certain amount and yours has adjusted beyond that.

Usual one for drivers airbag fault is the connector underneath the steering column, so dropping the knee panel is all you need to do to get to it.

One of my condenser fans seized years ago so they never ran and I recently noticed the other has now seized (probably due to lack of use) and it hasn't affected anything else.

One thing that will cause the compressor clutch to not kick in on hot days is if the clutch air gap is too wide. It should be between 16 and 30 thou but mine was nearer 40. It would work perfectly up to an ambient of around 22 degrees but as soon as it got hotter than that, just when it was needed, it wouldn't. Set the AC on Lo which should force it to come on, then tap the end of the clutch with a screwdriver handle, if it kicks in, that is the problem.

Yes it will. Doing an individual corner at a time shouldn't take too long with a tyre pump as you are only filling the air spring, probably a lot less volume than blowing up a tyre. Filling the whole system, all 4 air springs and the 9 litre reservoir, will take quite a bit longer (the best part of half an hour when I tried it with a fag lighter tyre pump).

dave3d wrote:

If you carry them with you, the car will never break down. On the one occasion you leave them at home is when you get a problem.

Exactly what happened to me. They sat in the boot for years and were never needed but the one time they were one of them wasn't in the boot and I needed a full set. Instead I tried using a tyre pump (in place of the dead pump) to pressurise the whole system but found that with trying to fill the reservoir as well as lift the car, it took nearly 30 minutes with the tyre pump running before the car started to lift. It just wasn't capable of supplying sufficient volume.

I found mine would lift from the bumpstops at around 5 bar, roughly 75psi. So tyre inflator is a must.

Get yourself a set of these https://www.ebay.co.uk/itm/274891528271, put one on each line and blow each corner up one at a time. I keep a set in the boot just in case (except only 3 of them were in the boot and the other was on the bench at home on the one occasion in 12 years that I've ever needed them). I don't like the idea of adding Tees and fitting them permanently as you are adding 12 more potential leak points.

Yes it is, ignition on, engine not running, in reverse gear and press and hold the Memory Store button. Message centre then displays Mirror Dip Off.

Tree clips are the ones that hold the insulation in place but don't have the hook for the washer pipe to clip into. For those you need ALR4425, https://rimmerbros.com/Item--i-ALR4425. You will probably find that the reason it has come out of the clip is that the pipes have shrunk a bit with age so they will no longer reach the clips, mine are dangling on both sides for that reason.

The stuff I've used in the past came from RS but it seems that it is no longer available in a small pot only https://uk.rs-online.com/web/p/adhesives/9185009. A bit pricey......

Been there, done that. Putting 12V onto the blend motor with the HEVAC still connected causes a small puff of blue smoke and the unmistakable smell of burning silicon. There's 4 small 8 legged LM272M op amps, and they don't like it up 'em as they used to say on Dad's Army.

It is a difference in the firmware but the reason for the error is that the early HEVAC would have driven the compressor clutch directly but on a later car it drives a relay to pull in the clutch. The early ones monitored the amount of current being drawn so will log a fault when driving a relay as it doesn't draw enough current.. Once it detects the fault it won't try to engage the clutch again. You can jumper the relay so it drives the clutch directly or add a resistor so it draws more current and the fault will go away.

@jacckk, it might be a good idea if you can copy and paste the guide on doing the mod on here. Then it won't get lost in the fb mire.