I do not have a regular mechanic though I know a couple of good shops.
I recently bought a used minivan and the previous owners assured me their mechanic told them the compressor was good; the AC just needed to be recharged.
I called both shops I know…one said they could do a pressure or dye (?) test and confirm whether the van needed a compressor, the other said there was no way to definitively test, and he launched into a long technical explanation as to why.
Given that recharging the AC is about $80 and a new compressor is about $800, I don’t want to be farting around wasting money. It’s a ten-year-old van that I bought for pretty cheap so the AC thing isn’t a deal-breaker.
If it makes a difference - 2001 Mercury Villager Estate, 142xxx miles. I bought it from the original owners and it’s almost pristine otherwise.
the dye test is to look for leaks, they put a small amount of tracer dye in the system and look at all the hoses and couplings with a black light. if there’s anything glowing, it’s leaking.
the pressure check might be to look at the compressor. it’s also possible the compressor clutch could have failed and it’s never turning on.
I’m not a mechanic…I’m far from it.
But I’ve recharged my own car A/C with a simple kit from Walmart.
The result is virtually instantaneous.
It may be worth trying…if it helps for a week, then you probably have a leak somewhere.
If it helps for six months…then it might be worth just recharging every now and then.
I’m sure someone more knowledgeable than I am will pop by to say if this was actually a good idea…
I do the same thing. The kits are cheap and there is a danger of over charging. I would only get the spendy’er kit that has a gauge.
I would like to edit this to say that, if your system is totally drained as in zero pressure these kits should not be used unless you have a way of pulling a vacuum on the system to get all the air and moisture out.
I have a stick pressure gauge that is handy for quick checks.
Well thanks! I’ve just been reading up on DIY AC charging kits and I think this may be worth a try. I’m in Michigan so really I only need AC a few months out of the year.
I know a couple of people who are reasonably knowleadgable shade tree mechanics so I can get some guidance re: the pressure thing.
Many junkyards are AC coolant recyclers and can recharge your AC for much less than the usual repair facility. The deal is they are giving you used coolant. As far as I know it’a as good as brand new stuff.
A compressor can not be shown to work properly unless the system is charged. In some cases (e.g. compressor locked up, compressor very noisy) a compressor can be condemned without the system being fully charged, but otherwise if the system is low then it must be recharged to evaluate its components. A performance test, which includes measuring system pressures and output air temperature, is the next step after charging.
A leak test, which can be done with dye and/or with an electronic detector, makes sense if the system was empty or low, though a leak may not be found if it’s small/slow.
Sounds like a long technical explanation of why they didn’t know what they were talking about, UNLESS they were telling you than a compressor cannot be tested without first charging the system (if it’s low). The latter is true, but can be explained in seconds.
If you’re saying you don’t want to spend the 80 unless you can be certain it won’t need the 800, you’re out of luck. Unless the compressor is obviously bad as I mentioned above, the system has to be charged to evaluate it. The compressor cannot work properly if there’s not enough refrigerant for it to work with.
We’re not talking about coolant (antifreeze/water mixture in the engine and radiator), we’re talking about refrigerant. There are places that recycle coolant and sell used coolant, so using incorrect terminology has a real risk of leading to major confusion.
The only concern with used refrigerant is contamination with other chemicals (often non-standard refrigerants), excess oil, and/or air. A place with the right kind of recycling equipment can offer pure or nearly pure (98+%) stuff, which is essentially as good as new.
Don’t know. When my mechanic replaced his MIL’s alternator and battery FOR FREE he wouldn’t let me out of his lot without topping off her freon (it’s an old car). As is obvious, he’s still my mechanic, though he struck out with my SIL 35 years ago.
A good shop can quickly check the charge and the compressor. They may be related. One failure mode for the compressor is a leak at the shaft seal. Therefore, your system could have a leak and it could also need a compressor because of that leak. However, you might top off the system and get by the season.
OK, the real simple version is this: If you need a charge, you have a leak somewhere in the system. Common leak sources are hose O-ring seals, compressor shaft seals and stem valve seals.
The man who launched into an extended “technical” explanation as to why it’s impossible to detect the leak is incompetent. Period.
Leaks can be a royal pain to detect at times, but not impossible to detect. Anything from engine off halogen detector testing of a charged system to using dye to locate a leak are common methods (dye is messy though).
That all said, I’ve been cash strapped more than a few times in my life and simply recharged the system, rather than finding the leak, as I couldn’t afford the permanent repair.
I agree with both your points. My concern is less with the technical area and more with the customer relations side. Here’s an illustration:
Customer: Do you do coolant flushes? I think my car is due for that.
Shop: Yes. We can do it today for $X.
Customer: Go ahead.
[An engine coolant flush is performed, customer pays and drives away but comes back upset.]
Customer: I just paid you $X for coolant service and my air conditioning still isn’t cold!
You can imagine the rest.
Now, a good shop will generally try to avoid such misunderstandings, but a customer who uses the wrong terms in a plausible way runs a serious risk of not only being disappointed but also having to accept that he asked for it. No one involved is going to be happy. Sadly, this sort of thing does happen occasionally.
[del]Minor[/del]Major nitpick. You’re AC runs any time you have your defogger/defroster on (the one that blows air across your windshield). So if you live in Michigan, more then likely you use your AC throughout most of the winter as well. Any time you’re trying to melt the ice off your windshield, you’re AC is running. Without it, you’re windshield would condensate (especially if there’s people in the car breathing hot humid air on a cold icy windshield). In fact, on some cars, you’ll see that when you hit the defogger button, the AC light will come on as well.
That’s not quite right. There might be some slight advantage to the dehumidifying effects of the AC, but the main reason why it comes on is to stop the AC system from seizing up from disuse all winter. On older cars, they recommended you run the AC once every couple of weeks in the winter before they came up with the brilliant idea of taking the human element out of the equation and simply forcing you to run it every time you ran the defroster. The car will still defrost just fine with a non-functional (or never installed) AC system.
I suppose it’s probably a combination of the two. I do remember seeing manuals that said to run it for 5 minutes once a month to keep the o-rings lubricated, but I do believe it’s a good idea to blow dry air on a cold window rather then humid air.
Thanks all!
It’s probably obvious I am not terribly mechanically-savvy. Although I do know the difference between coolant (which I’ve changed myself) and freon/refrigerant (of which I have little clue.) And on older cars I’ve owned, I knew to run the AC about once a month in winter.
So…I get that the system has to be charged for anyone to test for leaks. And, some leaks are very slow. And, if the fan doesn’t blow cold air, there is either a leak in the system or the compressor died.
So if I got to WalMart <shudder> or an auto parts store and purchase a recharging kit, with guage so I don’t over-pressurize the thing, I’ll either be good until October when it cools off, or I won’t.
So theoretically, it’s possible to keep doing the DIY recharging thing every now and again, if the leak is a slow or minor one. If the van won’t hold a charge, I take it to shop number one - the guy that didn’t give me the detailed explanation of why testing can’t work. And be prepared to either suck it up and pay about $800 for AC, or suck it up and live without AC.
(It should be said this is not my primary vehicle, but one reason I bought a minivan is for dog-hauling. One of my dogs, and the occasional rescue/transport dog, do not do well with heat.)
So my logical next step is to go buy one of these DIY kits, right?
How much are they (not legal in Wisconsin, so I’ve never seen one)? It might be worth skipping that step altogether if it’s to expensive and just biting the bullet and starting out at the shop.
