driven home from work in my P38 I parked it in direct sunlight so I had a little play around with the Air-con in the old bus..

I've been operating under the assumption that it didn't work, mostly due to the feeble blower output...

Anyway I turned the aircon on and the if the hieroglyphs on my HVAC are to be believed it was set to "low" the air coming out the dash seemed to be very cool, definitely colder than the ambient air outside, however upon inspection the clutch on the compressor isn't spinning with the pump when the air-con is engaged.

HOWEVER whenever I put the A/C on the engine note changes and she seems to bog down slightly, exactly what would happen when the clutch engages, however I can't see it doing much..

She does have the notebook on the HVAC panel, I've read some place that if the HVAC is in a fault condition it won't allow the compressor to operate?

BUT surely the engine wouldn't change note if nowt was happening??

Any ideas gents?
H

the compressor clutch might not be spinning but if the fuse for aircon is good the ecu will be thinking the compressor is working that would be why the engine drops a note

What do you mean, I turned the aircon on? It is on by default, poking the button marked AC OFF so it lights up does what it says, it turns it off. Clutch won't engage all the time, it will cut in and out as needed controlled by the pressure in the system. If the HEVAC has the book symbol showing it won't try to operate whatever caused the book to come on in the first place. So if you have a faulty blend motor, it won't try to operate the blend motors, if you have a faulty blower, it won't try to operate that blower but if it detects a fault with the clutch, it won't try to operate that. However, on a later car like yours, the HEVAC operates a relay which operates the clutch so it doesn't detect a fault if the clutch isn't engaging, only if the relay isn't operating.

Oh thanks Richard..

Most of the time the A/C light is on so yes it is off the majority of the time.

I think she has a blend motor and blower fault, is it possible to do the blend motors without taking out the entire dash?

AND can a HVAC fault be cleared without a nano?

Thanks

H

With certain acrobatics, blend motors are accessible. However you should know which one to access in the first place. Then, having handy some diagnostic tool is a godsend.

Why is the AC light on? Leave it so the light is off and the AC is working, far more likely to keep working that way. The worst thing you can do with AC is not use it and the P38 system is designed to blend hot and cold air so it assumes it will be always on. Blowers are easy enough to check by looking through the pollen filter holes to make sure they are both spinning. If only one is turning that explains a lack of airflow from the heater as the working one sucks air in on one side which instead of flowing through the matrix when it gets to the centre, carries on across the car and out the other side. Fixing the dead blower will turn the book symbol off if that was the cause.

Blend motors can be done without removing the dash. You can check which one is faulty by changing the temperature on each side from Lo to Hi and seeing it the air coming out changes temperature and altering where the flow goes using the buttons on the HEVAC to check the distribution motor. Passenger blend motor can be accessed by dropping the glovebox, distribution and drivers side motor can be accessed through the hole where the instruments live if you take the cluster out. Alternatively, a Nanocom will tell you what is causing the book symbol so you can deal with it.

Is there anything on your car that works as it should?

Thanks Richard..

To answer you question "does anything in your car work as it should" the answer to that is no not really.

To be fair I've spent the entirety of my ownership doing bits underneath to make her mechanically reliable, the interior creature comforts have had to wait.

Radio doesn't work.
Hvac doesn't really function
Cruise doesn't
Heated seats don't function
Heated windscreen doesn't

I need to get stuck in to be fair.

I bought her for £600 so can't really complain a student with no money and a want for the P38 that stemmed from reading LR mags when I was a nipper I knew nowt about them and bought the cheapest I could find, Not ignorent to the issues though I knew it would be a pain in the arse to be fair to it mechanically apart from a few EAS faults that were easy to fix with RRpub help she has never left me stranded. .

The chap I bought her off wasn't very car oriented so he hoon'd the living fuck out of it at every opportunity, at one point he admitted to driving to London everyday and averaging 100mph on the M'way..

I'd love to get another P38 in better nick, but the way prices are going that is an impossibility, and to be fair where is the fun in one that works LOL

I have the devil I know lol no use getting someone else's problem

From the bottom up, screen may well be the screen itself so cant really be repaired without a new screen although you could have checked that power was getting to it when you had the plenum off to do your water leak. At least that way you would know if it was the screen elements or something before it gets that far. Heated seats are a pita to repair but you can check under the seat to see which element is broken and if there is power there. Cruise is an easy one and can be done with the instrument cluster out. All it will need is a length of 4mm ID vacuum tube to replace the one from the brake pedal valve switch to the Tee by the actuator (and the two short lengths from the Tee). HEVAC probably needs a Marty zebra strip (from your comment on hieroglyphics in your last post). Even my mate Danny was able to do that job on the Vogue we have just returned to its former glory so it can't be that difficult as he's as ham-fisted as they come.

Radio is likely to be the DSP amp in the boot. You could be a guinea pig for me on that one. I've fitted one of Marty's replacements that involved chopping the original plug off and an awful lot of soldering in the boot so I'm working on a plug and play replacement using the original casing from the DSP amp but with two stereo amps and 4 crossovers inside. So it should be possible to unplug the DSP amp, fit this in its place and that will give you the front two channels and the sub while adding four more wires from the head unit to the amp to connect up the two rear channels (the DSP system only supplies left and right channels to the amp, the split and fade function to feed the rear speakers is done in the amp). The only problem I have at the moment is not having access to a car with the DSP system, working or not, to plug it in and try it to make sure it works and see what it sounds like. Once I've got it finished, you can try it on your car if you like.

Things that don't work as they should really annoy me, if it's there it should work and the fun in having everything working is in being able to get in it and use it (up to 416,400 now) without any worries. There's a lot to be gained from the devil you know. You know what the faults are, what you've done and what still needs to be done rather than giving up on it and buying someone else's pile of problems. That's why I spent £2,500 on an engine rebuild for mine rather than just getting a newer, lower mileage one to replace it with. I didn't really want to start all over again with the same problems I'd already dealt with on mine.

Thanks Richard.

Yep the HVAC needs a ribbon, I reckon I could do that.

Cruise control sounds an easy fix, i'll get on that.

The AMP idea would be fun, mine is missing the DSP after it self combusted and caused no end of BECM issues,

I ain't giving up on it, fixing it sounds like fun...

Maybe if there is another "summer camp" i'll chug over and ya'll can feast your eyes on the old beast LOL

H

When I got mine, cruise control wasn't working and assuming the worst, I was putting it to the back of the queue.

Then with the bonnet open for something else, I realised that the short lengths of pipe at the Tee were split. I got some new pipe delivered and for me it was literally a 60 second job to cut two lengths and plug them in. Cruise now works perfectly. Being a mechanical system I find it's not quite as precise as the more modern ones I'm familiar with, but still a lot easier on the 'cruise'.

Interesting discussion above though - regarding toys working/not working, or "the devil you know". I can relate to most of that. Work on my car has stalled because of "work" (paid employment!) and the return of colder weather; and I still can't find anyone really keen to remove and rebond the windscreen. It looks like our roads will be chokka this year with folk looking to 'holiday in the Highlands' so at least I'll have something to occupy my time when the sun returns.

I think the change in note is just when ecm grants the a/c. After grant, if the clutch has not engaged within about two minutes the service book symbol will come on, and at that precise moment you will get another change in tone. So i'd say your prob is between hevac and compressor, or the compressor clutch itself.
Check fuses and relays (esp fuse 42 10A, which is the battery feed to the ecu, without that one you' re going nowhere)
Put a 9v battery across the spades of the compressor...does clutch engage?
Engine off and 9v connected to spades... using a ferrous spanner, does the central spindle/nut on the clutch magnetise? If it does then check the gap on the clutch with a feeler gauge.

If the clutch IS working then pull the hevac ecu and test the BS line on the 16 B connector for ac on. When you turn to Ignition II it will start at 12v, and go to near zero when the ac is requested. If you toggle the ac switch you can watch this go high (off) and low (on).
Test the BG line on the 16 B connector for ecm grant. It will start at 5volts and should drop to zero ( grant) within 30s or so of start up. If not, try raising the revs to about 1500.
And lastly take your 9v battery and put the +ve to the BY pin (no 7 on the 8 W connector) and the negative to a good earth eg back of the cigar lighter...clutch should lock... If not then do a resistance check from pin7 to the +ve at the ac round connector, it should not be more than 10 ohms or so.
If resistance is high, then is your ac charged, if yes then you need to go to the rh kick panel and spray the hell out of positions 1,7,12 with contact cleaner, and if that still doesnt work then test the resistance from pin7 ( lower) to the +ve at the round compressor connector...if you get high resistance there then you prob want to pull the bumper and bridge the trinary switch and/or check the resistance across it. Shd be a few ohms only when closed. If the switch is toast then you can change it without refilling the ac.
Hope it helps

Thanks all..

Help greatly appreciated!