Air con problem

[Fantom]

Hi guys.
Bought an 03 172. Air con didn't work. So I had it re-gassed with my service and they said they detected no leaks and the system was almost empty so they charged me a fortune to fill it up.
Air con worked again, great, but for some reason it didn't feel that impressive. Not sure if that is just in my mind or not. Air was colder than outside air though so it was definitely working.
Anyway, its only about a month since then and hey presto the air con doesn't work. Blows like crazy trying to make it cold but the air is just normal. Its doesn't get cold.
Soooooo......has all the gas just leaked out??? Or is there something else that has packed up??
I can't see how the garage could miss a leak if there was one. How common is that?

So.... what do you suggest I check?

Thanks
Steve

 

[edde]

check the system for pressure again could be a leaking pipe.

 

[SkidMarx]

Gas has probably leaked out. Need to take it back so they can put tracer in the system and check it with a uv light. Most aircon machines do a leak test before the gas is put in, but if its only i slight leak they dont often pick it up.

Failing that the A/C pressure sensor couldve failed.

 

[Fantom]

How do I check the system for pressure???

There is a sticker under the bonnet saying that tracer had already been used on the car. I informed the garage of this as the previous owner must have also had problems.

 

[SkidMarx]

You can check it via clip on the Injection system. If the pressure in the system is lower than 4 bar ( i think ) then the compressor wont kick in.