Technical Aircon - broken pipe

[Billy The Kid]

re: Air-con faulty [broken pipe?]

(...) There should be high pressure and low pressure readings. What are they? That would help with diagnosis

I've got a question regarding those high/low pressure readings mentioned above...

mine are: (JTD 115, '02)
low - about 5
high - 10.9

but the **** A/C doesn't work at all it's refilled, there are no leaks, cabin filter has been replaced... Does anyone know something about those pressure readings?

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Well those pressures don't make any sense at all.
What units are you talking here? psi? bar? ... box of frogs?
Is this with air con compressor running?
Does the compressor clutch even engage?

Have a look here at an air con forum
http://www.eurocarparts.com/forum/default.asp

as just about everything that can go wrong is discussed there

 

[HONESTJOE]

re: Air-con faulty [broken pipe?]

Hi,
Had mine into Kwik Fit for re-gas and they told me it wouldnt let gas in at all, it empties every summer but now this is taking the mick. a car that wont accept the gas !:bang:

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Sounds like they were just trying to put gas into a non operating system. If it's fully charged then it doesn't need more

More information needed
Is the compressor clutch engaging?
Why did you take it in for regas?
Was it working at all before?
Has it ever worked?
Did it suddenly stop working?

 

[minimad99]

Condensor fan not working

Sorry to hijack a thread but may link somewhere?

Had my aircon system serviced today. The company did a vaccum, pressure test, then regassed the system. All fine so far no leaks and system holding perfectly.

The clutch is engaging correctly when aircon turned on but the condensor fan is not activating. We've checked the fuses and relays, all fine.
The fan itself works when a seperate feed is put to it manually it's just not being activated by the car when aircon on.
I'm not sure if it kicks in when too hot, in 4 years and 50,000 miles i've never had a problem.

The engineer said the fan should kick in to keep the system at about 15bar of pressure, if it doesn't turn on, the pressure continues to build up and this can cause problems in other parts of the system.
i saw the pressure doing this on his machine.

He thinks it's an electrical issue as everything else is fine, i could use the aircon when driving at speed as the system would air cool.

Now to my question........
how many electrical plugs/connectors are there on the system that could be dirty/faulty?

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

He thinks it's an electrical issue
Ha! Safe bet there then

Have you checked the actual fan connector? They've been known to cause problems.
If the fan doesn't work on either the slow OR the fast speed setting then i'd look at the fan connector, the last thing in the system as the low and high speeds come in from different relays ie two independant lines

I presume you found it when you jumped the fan directly. When you jumped the fan did you give it power AND a return or did you just put power in on one side? If you just put power in then the earth will be ok but if you jumped both sides then there might be a bad earth line from the fan if you haven't looked at that yet

Good news that the fan works so check for power to the fan and check the earth line. Thing's got to go then

 

[minimad99]

re: Air-con faulty [broken pipe?]

well a bit of an update,
just been out and given her a run, got up to temperture in approx 5 mins with 30-40mph driving.
after about 15 mins of driving sat with engine running for approx 5 mins revving it occasionally.
fan did not cut in but i did get an engine warning light, assume this is the "i'm about to explode warning"
after restart warning cleared

so i'm assuming these 2 faults are connected????

Decks,
when we jumped the fan, they guy used a probe thing on one of the connectors and the fan started. he had another gizzmo that lit up postive or negative. i think he used this on the fan connector, the connector had a positive but no negative/earth i believe.
where would i start to trace this dodgy earth if that is the problem?
cheers

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Aha! So it is a bad earth. Well that should be easy to trace

Looks like the fan earth goes straight from the fan connector N11 back to the battery on connector C1A.
I'd try your own earth line by jumping from the fan connector earth to a suitable earth and see if the fan works now ok just to check that's what's causing the problem. WATCH YOUR FINGERS NEAR THE FAN!!
Then I'd check out the connections from the earth to the battery. It's a short distance so i can't see any connectors being in the way.

A puncture probe is good for that, get them in most good automotive shops, you can then stab the wire along its length and see where the power or wire continuity stops. I expect it's just a bad connection near the battery

 

[HONESTJOE]

re: Air-con faulty [broken pipe?]

Hi,
Had the thing re-gassed 3 times now, each time they say there is no leak, ive checked fuse F19 7.5 near the battery and was fine. It just seemed to stop blowing cold a couple of months ago.

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Is the compressor clutch engaging?
You can tell by a metallic "clack" when you turn the air con on and by looking at the compressor drive pulley centre portion rotating
It won't work unless the compressor is being driven

 

[minimad99]

re: Air-con faulty [broken pipe?]

Decks,
Today i've
1). disconnected battery, disconnected and cleaned all three earth connectors on negative terminal with a wire brush and contact cleaner.They wern't that bad actually.

2). disconnected and cleaned the fan connector plug N11. Just to mention this has power going it even with ignition off, i used one of those crocodile clip with wire light up screwdriver thingies to find this, I assume this being a constant live is correct?

3). i then ran two seperate wires, one from the positive of the N11 plug to the fan itself (in theory just extending the existing wire) so power still going into the fan unit.
Then using my light up screwdriver i touched the 2nd terminal in the fan unit (not the plug N11) and it lit up, so i'm assuming that power is passing through the plug, down my wire into the fan unit and back out, phew!
I'm not sure if this is correct, perhaps you could confirm.

4). Then i ran my second wire from the 2nd terminal in the fan unit and touched the other end onto the negative terminal on the battery to earth it.
The fan instantly spun into life, so i know it works..... but i've bypassed the fan switch.

When you said "I'd try your own earth line by jumping from the fan connector earth to a suitable earth and see if the fan works now ok just to check that's what's causing the problem"
Did you mean have i have described above?

5). disconnected and cleaned the green thermostat switch. i know this is working as when i switched the ignition on i got a coolent temp warning message as i forgotten to plug it back in, LOL

While checking the wires on route to the battery i found that both the red and black from the n11 fan plug run into a silver box, photo attached, then back out and eventually into the battery area.

What is this box, could it be the route to the problem?

Sorry for the long post but i like to learn and you're a great teacher, creep creep

cheers
Neil

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Yes, you very nicely made your own earth for the fan and proved that it has power and that it works so, as we guessed, your earth line from the fan is duff

So, you could just make your earth with suitable size cable or aim to fix the problem

Whaddya fancy?

The silver box is an in line resistor with heat sink to provide the low speed fan power.

 

[minimad99]

re: Air-con faulty [broken pipe?]

i'm quite happy to make up a new earth cable.
Do you mean cut off the old earth from the fan plug N11 and join a new wire using suitable connector?
This assumes that the N11 IS the switch. I'm abit confused as to what component detects the overheating and switches the fan on. sorry

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Something troubles me, you say you have constant live at the fan even with ignition switched off? That doesn't sound right, the fan would be going all the time. Was this just after you'd turned the engine off?

Do you have some history? Has the fan ever worked properly? Any chance someone has purposely chopped the earth line?

Think we'll need to go through this one step at a time especially if someone else has been playing with it

(Click to enlarge)
Here's a wiring diag so we can see where we are

Check that power line into the fan again but with engine cold this time. Shouldn't be any power there with ignition off and engine cold

The way the system works is this
When the engine coolant temp gets to a certain temp OR the air con linear pressure switch says "Hey time for cooling" then the body computer supplies an earth to relay T6 which supplies the fan via a resistor which gives the slow fan setting.
If the engine temp reaches the higher lever OR the air con gets to higher pressures then the body computer calls the fire brigade and arms relay F7 which sends power directly to the fan giving it full power

When you turn the engine off power is still supplied to the fan, if necessary, for a while to cool the engine down

 

[minimad99]

re: Air-con faulty [broken pipe?]

Just been out and checked it again it's still live with keys in my pocket! and a cold engine.
just to note, I am testing this at the connector inside the N11 fan plug that is connected to the red wire.
I was wondering about that hence my question about what does the switching on/off when engine gets too hot.

I had assumed it was working as i've never had any issues, although i did have a front end accident end of 2005 and a lot was replaced, rad, bumper, bonnet, etc, etc maybe a wire got crushed then.

While checking today the wiring all looks origanal and untampered, still has the black fabric covering all over it.

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Oh Wait a mo, you have a JTD don't you. The rad fan system works in a totally different way on the JTD. Hang fire a bit and I'll see what i can find

 

[minimad99]

re: Air-con faulty [broken pipe?]

thanks, i really appeciate it.

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Ok here's the wiring diag for the JTD

for some weird reason it's a totally different system so the constant live you're getting is normal and all ok. Phew!


NB Check fuses F6 and F16 first - look in the wiring diag above for locations

If they're ok then I'd then check for continuity between the fan earth and the M10a unit. The earth line goes through a control unit M10A shown here in your engine bay. If that's ok then check the M10a unit has it's connection back to earth on the battery. If all that checks out then there maybe a fault actually in the M10 unit

 

[minimad99]

re: Air-con faulty [broken pipe?]

Decks,
Thanks for that, i've just found that diagram on elearn, M10 is the ECU, i think its the M150 that is the fan control unit. I believe this is the silver box that posted a photo of earlier.
there are no removable connections to it though both sets of wires go straight in.

Can you confirm that if i cut away a very small bit of insulation working my way along using my light up screwdriver to test, i'm looking for it to light up where there is an earth and if not then i've found the duff bit of wire?

thanks again
neil

 

[Deckchair5]

re: Air-con faulty [broken pipe?]

Before you do anything major, have you checked both fuses F6 and F16?