Bloomin' hot now

[Vic Evans]

We were out in Mme's C4 yesterday driving for about 1/2 hour for a hospital visit in 30deg C +temperature. The air con was working fine but when we set off for home after leaving the car for a couple of hours in the sun the A/C wouldn't cool. She was driving & I was button pushing to try to get it working & the only strange thing I noticed was the auto door locking system which usually operates after 100m or so clicked off/on when I'm sure I was nowhere near the button. Red herring probably but thought worth a mention.
I don't think the system has ever been topped up so suspect this. Trouble is our local Citroen garage is inundated with car A/C problems & can't look at her car for 2 weeks.
In the meantime is there anything I can check?

[PaulC5]

If it is too hot the air con will not work to reduce the load on the engine. Have a look in your handbook, there should be something about it but I could not see anything. See if it works after it has cooled down.

[Vic Evans]

If it is too hot the air con will not work to reduce the load on the engine. Have a look in your handbook, there should be something about it but I could not see anything. See if it works after it has cooled down.

Thanks for info.
We've got both French & English handbooks. Can't see anything about that.
Mentions sun sensor on dash but doesn't say where it is.
I've just had a quick try as car is as cold as it'll get in our crinkly tin roofed barn.
By hand touch it does seem to be doing a bit of cooling but not much & certainly not the cold -cold it normally has. This of course could just be hope over facts.
She's taken car out now so later I'll stick a 'leccy thermometer sensor in an outlet grill & measure exact leaving air temp.

[xsara92]

I've been trying to get A/C working on my Xsara Pic recently. Couple of other things worth lookng at:

1. When you press the A/C button, do you hear the relay click corresponding to the compressor coming on?
It is possible that the clutch on your compressor struggles to engage when the engine revs are low, my garage told me this happens more frequently when comps are in their twilight years.
2. Is your engine fan working?
3. A blocked cabin filter can also lead to intermittent A/C operation.

[Vic Evans]

Cheers xsara92
I'll have a look in the morning when it's a bit cooler.

[Vic Evans]

Cheers xsara92
I'll have a look in the morning when it's a bit cooler.

Just tried it as now cool in barn.
Can't hear relay or compressor clutch engage at tick over or higher revs.
Can't tell if engine fan is working as engine cold but I assume it is as no overheat when it was last out on run. Mme has taken car out so maybe I can tell when she returns.
Don't think cabin filter blocked as lots of air through vents when on ext. air setting.

Looks like job for garage.

[admiral51]

My Understanding of how A/C works is as follows so please feel free to laugh
There is the Low Pressure (LP) and High Pressure (HP) side of the system. LP is not enough gas and HP is it is getting to hot.
The cooling fan should kick in when the A/C compessor is engaged to help cool the HP side of the system which will include engine bay heat and engine coolant temperature. I think this is what PaulC5 was referring to but i could be wrong.
Not sure if it is just Sod's Law that something breaks when you actually need it the most but 2 out of our 4 lorries at work have suffered no A/C in the last 2 weeks. A drain,pressure test and regas have solved the issue.
Not sure what it is like in France but here in the UK you can go to any garage that does A/C regas. Are there any local A/C mobile specialist that would come out to you. Atleast that way you can see what they actually do ?

Colin

[PaulC5]

The car air con works like a fridge. The compressor pressurises and raises the temperature of the gas so it has a higher boiling point and can be condensed at the front of the car by the outside air in the condenser to liquid. The liquid then goes to a pressure control valve (expansion valve) that drops the pressure so it evaporates to a gas at a low temperature and goes through the evaporator in the heater unit and provides cold air and the gas goes round to the compressor again. The refrigerant pipe to the compressor will be cold and the one from it hot if the air con is working.

There are things that I think prevent the air con working, if the refrigerant pressure is too high possibly due to the radiator fan not working to control the high pressure or a blocked condenser, if it is too low due to not enough refrigerant, if the outside air temperature is too low (possibly around 6°C), the cabin fan is not running, if the engine coolant temperature is too high and possibly if the outside temperature is too high.

[Vic Evans]

Thanks for interest folks.
I took the car out today & when I returned & parked up in the hot barn I gave it another simple test.
Engine running I put it in fresh air mode / auto & felt leaving air temp which was deffo warm.
I let things stabilise for about 10 secs Pushed 'on' a/c button & deffo felt a drop in temperature.
Let things stabilise & turned 'off' a/c. Deffo felt a rise in temp.
Repeated this a few more times with same results.
My conclusion is that mechanically things are working & it's lost gas/pressure over its 12 untouched years since new & simply needs a re-gas.
Only just opened up the forum & read PaulC5's post so maybe I'll try that tomorrow to confirm my conclusion.
The above reminded me of my old Pug 806 which would lose it's cooling efficiency over a year or so due to a small leak behind the dash. A re-gas would sort it until the next time. I don't bother with it anymore as 1,000 km/year doesn't warrant it.

[PaulC5]

If it has gone 12 years without a re-gas it is doing well. When done they will check for leaks. Our 2007 C5 I had re-gassed at about 7 years old as it was not cooling enough and again about 14 years old but then it had a leak in the condenser so needed a new one. Our 2019 308 needed a new condenser last year as it had a leak, I spotted it due to oil on the front bumper valance that had dripped down when I was looking under the car for another reason.