How to Diagnose Aircon issues

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cookan
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How to Diagnose Aircon issues

Post by cookan » Thu Apr 23, 2015 6:46 pm

Hi guys,
well...turned the aircon on today...worked last time I used it (last year)...today, blowing warm air..

So, blowers work and when I press Aircon on I can feel engine change revs.

When I switch the engine off however, I hear what I think sounds like a pressure leak...almost like the racing noise you get from spinning a bearing however the engine has well and truly stopped so there's nothing still turning at that point (i.e It can't be the compressor as the compressor is no longer turning)..it comes from the vicinity of the central console (behind gear lever area or at some point behind the point between gear lever and radio)...the noise continues for about 3-5 seconds..after the engine has stopped.

So without wanting to influence anyone...It sounds to me like any pressure that has been built up whilst driving, is escaping...and when the engine is turned off you hear the final remnants escape...

my question is therefore...how do I go about problem solving this...any idea where the pipes run...anyone had the same noise..not much point in taking it to a regassing place if they're just going to tell me what I already think I know...might as well replace any leaky pipes first..

thanks,
Ant.
1995 M reg 2WD AFT in green/grey (and an Oakley Thermonuclear Protection decal for some reason!)
Gasy
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Re: How to Diagnose Aircon issues

Post by Gasy » Thu Apr 23, 2015 7:12 pm

You can find gas / air leaks in pipes by spraying them with a soapy water solution and look for the bubbles
Get a trigger spray bottle and put in a good squirt of fairy liquid fill with water and shake
Then spray over pipes looking for leaks

That's how we find gas leaks , SOZ don't know much about air con someone will be along soon
Gas safe heating engineer / plumber if you need any advice just shout.
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jimmo62
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Re: How to Diagnose Aircon issues

Post by jimmo62 » Thu Apr 23, 2015 7:29 pm

re the noise you can hear when the engine has stopped - that could be the small fan/sensor unit behind the small grille cut into the dash near the glovebox - this fan samples the air temp in the cabin by blowing it over a sensor. easy to remove from the glovebox compartment to check, the do get quite bunged up
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cookan
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Re: How to Diagnose Aircon issues

Post by cookan » Thu Apr 23, 2015 7:31 pm

Mines just aircon without climate control..would it still have that ?
Thanks
Ant
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Northern Bongolow
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Re: How to Diagnose Aircon issues

Post by Northern Bongolow » Thu Apr 23, 2015 7:52 pm

jimmo62 wrote:re the noise you can hear when the engine has stopped - that could be the small fan/sensor unit behind the small grille cut into the dash near the glovebox - this fan samples the air temp in the cabin by blowing it over a sensor. easy to remove from the glovebox compartment to check, the do get quite bunged up
thats the noise me thinks too. :) .

at the front of the rad is a bottle with the refrigerant in it.
61-500 in the drawing below.

http://lushprojects.com/bongopartsmk2/c ... 1of02.html.

on the top of it is a plug, remove the plug and short the two pins together ON THE PLUG with a piece of wire, then switch the aircon on as normal, if it all kicks in that means just needs regas and leak fixed. if it doesnt kick in then something mechanical or the belt.

where the plug plugs into the unit there is a viewing window, clean it, you should be able to see the oil/refrigerant passing the viewing window.
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mikeWalsall
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Re: How to Diagnose Aircon issues

Post by mikeWalsall » Thu Apr 23, 2015 8:45 pm

As an aside question ...

Why do most people think air conditioning is some thing to do with only supplying cold air in the summer .. ??

I have never seen it 'advertised' as iced air devise or what have you .. I have always assumed it is something to do with conditioning the air in the closed environment we are in .. I leave mine on winter and summer ..
JAL Mushroom roof,12/240v, fridge, cooker, sink, LPG V6 .. (written off @ £5500 Nov 2016)
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Re: How to Diagnose Aircon issues

Post by Gasy » Fri Apr 24, 2015 7:27 am

^^^^
Me to in the van and bongo
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cookan
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Re: How to Diagnose Aircon issues

Post by cookan » Fri Apr 24, 2015 9:39 am

Northern Bongolow wrote:
jimmo62 wrote:re the noise you can hear when the engine has stopped - that could be the small fan/sensor unit behind the small grille cut into the dash near the glovebox - this fan samples the air temp in the cabin by blowing it over a sensor. easy to remove from the glovebox compartment to check, the do get quite bunged up
thanks guys, ok..so the noise comes from behind the centre vents..and can be heard under the bonnet the opposite side where there's a big box thing I assume to be the condenser ? sounds a bit like a fridge I guess thinking about it..


I haven't taken the plug off the refrigerant bottle to test, but the aircon pump etc all kicks in anyway when I switch aircon on..so didn't think I needed to test that. As soon as aircon pushed in, the Rad fans fire up and revs go up a little.

I do see fluid flowing past the inspection window.

As an aside, the aircon since I've had the van, has taken a while to get cold...maybe 5 or so mins before it started blowing really cold. I've had the van for about 4 years now.

Given that I see fluid in the window, does that mean there's no leak and it just needs a regas ? I can't see any evidence in the service history for the last 10 years of it being regassed...
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Poohbear
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Re: How to Diagnose Aircon issues

Post by Poohbear » Fri Apr 24, 2015 10:33 am

First of all, as nobody appears to have mentioned it, you need to use your aircon at least once every couple of weeks all year round otherwise the seals in the compressor dry out and you then start to allow moisture into the system which causes corrosion and eventually leaks.

It sounds like you have a leak and need a re-gas. Any good aircon specialist will leak test before putting gas in. Don't use Halfrauds or KwikFit!
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Diplomat
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Re: How to Diagnose Aircon issues

Post by Diplomat » Fri Apr 24, 2015 10:01 pm

Poohbear wrote:First of all, as nobody appears to have mentioned it, you need to use your aircon at least once every couple of weeks all year round otherwise the seals in the compressor dry out and you then start to allow moisture into the system which causes corrosion and eventually leaks.

I!
I hardly ever used mine but it always worked when I did. Eventually I modified it to provide extra radiator cooling in traffic jams by disconnecting the electro magnetic clutch, bypassing the gas sensor and just using the dashboard switch to bring the two massive fans into action. I've enjoyed a lifetime of opening the window in hot weather and most other times as well.
How else would people hear me telling them to "Get on with it!" at junctions and roundabouts?


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Northern Bongolow
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Re: How to Diagnose Aircon issues

Post by Northern Bongolow » Fri Apr 24, 2015 10:24 pm

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cookan
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Re: How to Diagnose Aircon issues

Post by cookan » Thu May 07, 2015 6:08 pm

phew...,nice local chap popped by on the way home..checked the condition of the pipes then extracted all 130g of gas from the system...he then vacuumed it on the low pressure side to avoid removing any oil, ran a diagnostic leak test, charged it with dye for later problem solving and regassed with 950g. Temp at vent now 6 degrees with fans on full so gladly, no mechanical issues (as yet!). Let's hope for good times in France this year !

thanks,
Ant.
1995 M reg 2WD AFT in green/grey (and an Oakley Thermonuclear Protection decal for some reason!)
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