Does anyone know how they do the leak test? It should be with dry nitrogen. What pressure do they test it to?
A leak test with dry nitrogen is not guaranteed to show up every leak. If there is no leak with 250-300 psi Nitrogen, I will then re-gas with dye added and see if there is an immediate leak. If not I send the customer away and re-book for a few days later to re-check.
£44.95 is a very cheap price especially as the price of refrigerant has gone up so much recently.
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PS: DO NOT ATTEMPT TO WORK ON YOUR A/C SYSTEM YOURSELF - IT IS TOO DANGEROUS
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I think they only do a vacuum test. They seem to use those all in one units, so I presume they try to empty the system then try to hold a vacuum for a few minutes. I don't see how they can do much else for the cost.
Of course they are just doing the easy stuff and sending anything else away.
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i took the risk at KF yesterday and this is what i made of the regas
the machine is a cooltech ac650 pro.
from what i could gather this was what the machine does
1) The kwik fit technician(!) manually selects your model on the machine- watch like a hawk while they do this to ensure it?s your car- to be fair to the guy he checked the compresssor model number to ensure it matched what was on the screen
2) They take out old oil and gas and is measured approx 5mins
3) Some sort of leak test? 5mins
4) Vacuum for 20 mines
5) A leak and pressure test 10mins
6) Refill with new oil (mine was 15ml) and gas (800grams) 5mins
The whole process takes around an hour and is all done by the machine-no kwik fit input (apart from car details) which is good. The centre vent temp was measured around 6C after and feels much better.
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The leak test that the machine runs is simply a vacuum check. They pull a vacuum for 20 mins, then let it sit for 5 mins while the machine monitors the vacuum level. Any loss of vacuum over 200mbar and it fails.
But using vacuum to check for leaks is not very good, as you've only got 14.7psi of air pressure trying to get in over a short period, whereas when the system is fully charged you have 100psi trying to get out over a long period. But it's the best you can do with a machine like this.
Their procedure is to only service cars that come in with functioning a/c. So by default they won't ever find any leaks. The bottom line is - when the machine says it's passed, it's only really passed a vacuum leak check, not a full pressure leakdown test. Almost anything, unless it has a large hole from something like a stone through the condensor, will pass a simple vacuum check. They've run into a few problems where they've been sticking the machine on empty systems, it passes the 'leak check', they fill it up, then of course 2 weeks later it quits again. That's not the business KF are supposed to be in, or want to get into. They want to just cherry pick (and who can blame them) the nice simple jobs where they recover 500g from a fully functioning a/c system, and put back in the 600g as specified, with as little user input as possible.
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I have a 2002 Zafira and had a similar problem. It was the condenser that had a leak. It did not show up after a vacumn test! I wasted 3 refills before it was diagnosed. In the end a guy came round and fitted a new condenser and regassed it and chaged me around £250. Been great since, although it's never been as cold as other cars I've had, even when new. I was also told to use it even in winter other wise the seals go.
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