Any air conditioning experts on here?

[dieselnutjob]

I am (was) planning to drive to Spain and back this year.

 

My wife's family are from Cordoba where is it gets up to about 45 deg C in August, so air conditioning is absolutely essential.

 

I was planning to go there in our 806.

 

A few weeks ago the air conditioning packed up.  I put a bit of gas in it from a bottle that I got from Halfords, and it started working again for a while.

 

So I took it to a local garage were the guy is friendly and has all the equipment.

 

He found that the low pressure service port was leaking, so he vacuumed all the gas out, fitted a new valve, and regassed (along with oil and leak dye).  I watched him do this, including the bit were the machine goes to a vacuum and then asks you to watch the guage for five minutes, and it did indeed retain the vacuum.

 

Now I am finding that

 

If it hot then the AC doesn't work.  The fan rad fan doesn't come on and the compressor doesn't click.  It seems that if you drive around for a bit then sometimes it comes on.  Why is this?  It the air going through the condensor cooling the system to the point that the pressure switch flips?

 

Yesterday once it had cooled a bit it worked, but if turned off and then back on did not come on.

 

This is a manual system so no climatronic but I'm struggling a bit to see how it is controlled.  I think maybe that the compressor is controlled by the engine ECU (it's a HDI).  However I put my Peugeot Planet diagnostic computer on it (this is a dealer level factory tool) and could find no inputs or outputs in there except for the "AC defeat" feature (I think that this allows the ECU to turn off AC if you ask for 100% power).

 

I am starting to wonder if the pressure switch is playing up (Peugeot call it a pressostat or something).  According to the diagnostics you can bypass it by shorting pins 1 & 2 together.  I guess that this is only a safe thing to do if you have pressure guages on the system though.

 

I don't understand why the pressostat has so many pins on it.  Is it an over and under pressure detector?

 

I don't understand how the system knows to turn off when the evaporator gets too cold (if you turn off the interior blower it cycles the AC on and off as the evaporator gets cold).

 

Can anyone shed any light on how this thing actually works?

 

My current thinking is to just go back to the garage during the say when it's really hot and see if he can figure it out.

 

or something

[dieselnutjob]

some answers

http://www.youtube.com/watch?v=UT06QUfqf9o

[Shep Shepherd]

The very same thing is occurring with TV2's aircon at the moment, which is upsetting me a great deal

 

The general consensus amongst 850 and S/V70 people is that the compressor's clutch needs re-shimming, but I have no idea how to do this. Can anyone help me?

[dieselnutjob]

on the 806 I don't think that it's the clutch.

 

The reason I think that is because the rad cooling fan isn't coming on either.

 

I will have to have it pressure tested. If there is enough gas in the system and it doesn't switch on then I think that it can only be the pressure switch.  It seems that I can short the switch out as well to prove the point.

[dieselnutjob]

I think I found the fault.

 

Buried deep in the dash I found the relay that does the AC and the engine cooling fan.

 

I found that if I give the relay a sharp tap that the AC and fan come on.

 

It's a wierd thing. Seems to be go two contacts in one unit and it has six pins instead of four.

[Vanny]

So I took it to a local garage were the guy is friendly and has all the equipment.

 

 

Erm, sounds like he has a recharge trolley. These are completely hopeless for diagnosing faults. You need OFN at 50psi to find a leak safely and accurately. Always plump for a 'mobile' air con man, with individual components. Much better value for money!

 

I believe (and could be wrong) that pins 1 and 2 bridge the LOW pressure switch, so will bring life to a discharged system. Not recommended for long term running, but a relatively safe "quik'n dirty" test. It does have HIGH and LOW pressure in the switch, normally HIGH pressure trigger will occur when stationary and the fans have stopped working.

 

The 'cold' knob on your 806 might well trigger a microswitch to kick the system in if you don't have a seperate AC button.

 

Evap temp is metered by a thermistor that is shoved into the fins of the evaporator in what should be the coldest spot. 

 

Under the filling port (either one) is a schrader valve (like a tyre valve) give the pin a little push and if gas wooshes out then you probably have a half way decent charge. If nothing comes out, erm, you've got no gas. This test is allowed even under F-Gas regulations! If there is enough to make a woosh then the system should at least kick in, even if only for a few seconds. 

 

But depending on how that relay works, it could have a fair wack of current gong through it, and relays under high draw loads always fail first!

[dieselnutjob]

I believe (and could be wrong) that pins 1 and 2 bridge the LOW pressure switch, so will bring life to a discharged system.

Actually you are right. I tried shorting pins 1 and 2 last night and the AC did work until the relay overheated (I didn't know that was happening but now I do)

 

I have a Halfords recharge bottle and guage anyway so I can always see if there is some pressure in there.

 

Yes he has a Sun recharge machine and a wand that detected gas leaking out of one of the Schraeder valves. It got the job done and there is leak dye in there now in case of future problems.

[e287yba]

He should be repressurising with Nitrogen (which is inert, rather than the refrigerant which is rather nasty environmentally and similarly nasty to humans if it leaks out over a hot exhaust ) then pressure testing to see if there are any leaks - and finally refilling with the proper refrigerant only if there aren't any leaks seen on testing... Nothing wrong with UV-sensitive leak dye in the system , and I assume he injected some lubricant for the seals and pumps etc too?

 

This should also be all-inclusive, part of his service...

 

 

[Vanny]

and similarly nasty to humans if it leaks out over a hot exhaust

 

Have you been watching those comedy propaganda films about R134/R1234yf being super uber flammable and we're all gonna die, paid for buy the people developing the 500psi CO2 systems? I wouldn't believe everything you hear on the Internetz.

 

 

Also, UV leak dye, works only once. After that every time you have a fault the same leak will be blamed again and again because you can't completely remove the dye so it will always show up. When i was trained up, the trainer made a very compelling case for never putting leak detector dye in a system and i was convinced enough that i never do, and won't allow it in my cars. 

[dieselnutjob]

I pulled this "relay" out of the dash and asked my Peugeot dealer for a price.

 

£70

 

So I took the cover off

 

 

 

It's a bit more than a relay and actually only has one set of contacts.

 

In the photo you can see a circle in the solder above the "691" which is a crack in the solder.

 

I resoldered just that joint and now the AC works perfectly 

[Guest rocks]

Hi 

 

I'm new to this forum and hope you had a good trip to Spain.

 

I am having an identical problem with my 2001 Citroen Synergie (Peugeot 806 in all but name), would you mind letting me know, how  I can  get to your relay? and where is the pressostat?

[Bren]

I pulled this "relay" out of the dash and asked my Peugeot dealer for a price.

 

£70

 

So I took the cover off

 

 

 

 

 

It's a bit more than a relay and actually only has one set of contacts.

 

In the photo you can see a circle in the solder above the "691" which is a crack in the solder.

 

I resoldered just that joint and now the AC works perfectly 

 

Looks like a miniature spool of welding wire on top.

[dieselnutjob]

Hi 

 

I'm new to this forum and hope you had a good trip to Spain.

 

I am having an identical problem with my 2001 Citroen Synergie (Peugeot 806 in all but name), would you mind letting me know, how  I can  get to your relay? and where is the pressostat?

 

 

to the left of the clutch pedal but a bit higher.  I would say about the same height as the pivot point of the pedal

[PhilA]

Did you clean the contacts on the relay up whilst you had it in bits?

 

Looks like it's gotten wet, that's driven the resistance of the contacts up, it's gotten hot and caused a cold joint crack in the solder.

If you didn't, there's a good chance the same problem will manifest again (typically at the point you need the aircon the most, when the thing's been on and passing current the most).

 

Try explaining to someone in Spanish that you need a soldering iron*

 

--Phil

 

 

 

*if you can then, well... ok then.

[Guest rocks]

Please excuse my ignorance!

Hi I couldn't find anything to the left of the clutch pedal, but these are above it, am I getting warm?

[Guest rocks]

I mean't these sorry!

[purplebargeken]

You are indeed getting warm if the A/C isn't working......... 

[Junkman]

My wife's family are from Cordoba where is it gets up to about 45 deg C in August, so air conditioning is a nice First World thing to have, but not absolutely essential, what pretty much every Shiter having been there by car during the past 100 odd years can confirm.

 

EFA.