Air Con advice please

[BrianPeter]

Still sorting niggles in my 2008 Berlingo Multispace. The heater fan now works, but the aircon doesn’t. The little light on the switch comes on, but that’s all. 
I found the two valves (bit like tyre valves) in the pipes - a lower one and an upper one in what looks like a small expansion tank - and pressed the centre to see if gas was present. A very feeble hiss from the top one, and less from the lower one. 
I assume there’s no gas - does the aircon gas just run out over time, or is it likely to be a leak - in which case a bit pointless to take it in for re-gassing.
I don’t want to throw much more money at this vehicle, so am nervous about just handing it over to some anonymous aircon place to fix - could be an open-ended spendfest…
What should I be checking first to avoid unnecessary expense?

Any thoughts / advice gratefully received..

Thank you

[LukeC]

I've just had mine nitrogen tested as it was failing on me, and decided it was better to pay £30 for a test rather than regas and find it was a leak. Turns out. There was a hole in the condenser, my van is a sweat box without it. It might be an expensive test, but if it saves you a wasted regas, then it's worth it. If you need parts, then the regas should be included in the total parts/labour costs.

[BrianPeter]

Thanks.
Apparently KwikFit offer a "recharge or no charge" if they find a leak and can’t complete the re-charge, so perhaps I’ll try that first.

[LukeC]

I didn't know about that. That's the best way to go as it'll be free! As long as the don't say you have to have the work done with them and it be extortionate.

[geoff]

Thanks.
Apparently KwikFit offer a "recharge or no charge" if they find a leak and can’t complete the re-charge, so perhaps I’ll try that first.

I have an AirCon issue as well so the KwikFit information is of interest.

Can I ask you if for example I go for a regas and the gas is sufficient already and there is another issue - eg a sensor or a control valve not working - will they still charge, will they diagnose the fault as well ?

Obviously I want to get a fix and or a diagnosis for minimum cost 

I know I know I could go to KwikFix and ask but I don't trust these people as a consequence of experiences gained.

[BrianPeter]

All I know about the Kwikfit deal is what came up on google. Not sure if there are strings attached. I’m planning to go in and ask. I’ll post when I know more.