Previa ac test

You can't check the charge until it's running. The only thing you can check is to see if it's totally empty, or still has some. Just punch the valve pin and see if any pressure. If it hasn't been out too long, a belt may be all you need. If it's leaking fast, it won't have anything in it. But if it still has refrigerent, if it has a leak, it's probably fairly small. All you can do is get a new belt and go from there. Hope your clutch didn't seaze, and thats why the belt is gone.. I've had that happen before in a chevy chevette. Put so much squealing drag on the engine it killed it at stop lights.. I had to get out and cut it with a knife. The longer it sits without working, the more likely you will develop seal leaks, so I wouldn't wait too long to check it out. You might get lucky and have the belt be the only real problem. Might need a top off of refrigerent, but that can be had for less than $175.. MK

As MK suggested, you need to have the belt installed to check the AC's function. The problem with releasing refrigerant from the schrader valve is that even a small amount of refrigerant lost will diminish the AC's capacity a little, and it is illegal to vent refrigerant to the atmosphere.

You should be able to replace the belt in a half our or hour or so. With the AC running, look at the sight glass on the receiver drier in front of the condenser. The receiver drier is a metal cylinder about the size of an aerosol can with metal lines running in and out and a dime-sized glass window on top. With the AC running and he system fully charged, you should see a clear liquid running past the glass. If you see foam or nothing in the sight glass, the system needs charging. With the belt installed, if the compressor is seized, you will hear a squeal, the system should shut itself down, and the AC light on the dashboard should start blinking, indicating a problem.

Oops. Shhhhh. ;-) I have good reason to believe I have some charge left, but I would not break the law.

You overestimate me, but thanks.

With

With the belt installed, if the

OK, there WAS some squealing when the ac was still sort of working. I say sort of because even after it was recharged 6-7 years ago it was never very cold. It started squealing a couple years ago when I ran the ac, then it stopped squealing (I think) last year. I took this to be a good sign but it probably just meant the belt broke about then.

the belt pulley turn freely on the ac unit-does this mean the compressor/clutch is probably OK?

I did another test. With the ac on, the belt wheel spins with the rest of the (whatever you call it) compressor drive when turned by hand. When the ac is off, the belt wheel spins independently of the compressor when turned by hand. I take this to mean the clutch is good, because its engaging the two when turned on.

Yes, the compressor clutch is working, and if you can turn the compressor by hand, then it is not seized. If you think your system is charged, install a new belt and fire her up!

And do I just take the alternator belt off and loosen the compressor to install the ac belt, or is there a more involved procedure?

"do I just take the alternator belt off and loosen the compressor to install the ac belt"

yep

IIRC, all you have to do is remove the alternator belt, loosen the compressor, and swap the belts. Since you are going to have to remove the alternator belt, you may want to replace it if it is over 60K miles.

On Jun 16, 10:27 am, "Ray O"

Heck I'm going on 2 hours of spraying and trying to just loosen the compressor up without stripping the nut.

you may need to loosen the compressor mounting bolts, in addition to the tension/adjustment bolt. just loosening the tension/adjustment bolt may not be good enough to loosen the compressor. BTW, I just checked MY Previa and the tension/adjustment bolt is held on by a 12mm nut. I'd think your is the same as mine. loosen the tension/adjustment nut/bolt, loosen the tension/adjustment wing bolt, and loosen the 2 bottom compressor mounting bolts. that should loosen the compressor up so you can remove the belt.

Mine is a 14 mm. An almost stripped 14 mm now. :( It just wont budge after 16 years of Minnesota. And I havent even seen the lower bolts yet, and its too dark to look anymore tonight. I might have to take the van in and have someone loosen those 3 for me.

The wingnut is behind the freaking hoses so its hard to get a grip on. It hasnt budged yet either, but I've been concentrating on stripping that other one.

I'd think your is the same as mine. loosen the

At least I know I can get the alternator bolt loose, I've had those loose before. If I can get to that point.

Get some good penetrant like Kano Labs "Kroil" or MARS Chemical "Rust Buster" (alcohol based, NSF Approved safe for use on food service equipment) and let it soak in overnight.

(WD-40 is NOT a proper penetrant in the class of a dedicated compound for the use, there are many better choices.)

If that doesn't work, find a way to get some spot heat on the bolt area and get it nice and toasty (electric heat gun for confined spaces on a car, NO OPEN FLAMES!) and hit it with the penetrant again, let the heat suck it into the threads.

Then wait some more and try it again.

Do NOT Try using pliers on that wingnut - if you put all the stress on one wing while turning, you'll just snap it off.

You can make a dedicated socket or tool for turning a wingnut with regular socket wrenches - the easy way is to take a socket and cut a slot through it with an abrasive chop saw or a hacksaw to fit over the wings. If that won't work and you have access to a welder and a little ingenuity, you can make a special socket just for wingnuts.

Once you get the old bolt out, go get a fresh one. And the wingnut can be replaced with a proper hex nut. Why go through this again?

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I got the wingnut loose finally. The tension nut is still stuck. Will get some P-fluid tomorrow, wd-40 is all I had and I'm miles from town. I cant get a belt until Monday so there's no hurry-except I leave x- country by Wed. ;-)

don't forget to use a 6 point socket instead of a 12 point. there may still be enough meat left on the nut for the 6 point socket to grab.

"Mine is a 14 mm."

you're right about the nut being 14mm. I didn't take a very close look and guessed the size by what I saw.

I forget what year the OP's vehicle is, but DO NOT MIX R-12 and R-134-A!

As Bruce says, use a penetrating oil made for loosening rusted bolts. Spray, tap the part lightly with a hammer, wait an hour or 2, and repeat every hour or 2 until the end of the day. Let is soak overnight, and repeat the process of spraying, tapping, and waiting. After a day or 2, you should be able to loosen the nut.

Well you are getting ahead, but thats the next question/problem. I called the dealoer that serviced the ac a few years ago, and they said they "probably" used 134. But there is no indication of that. The R-12 sticker is still there. There are no adapters or anything to indicate they didnt use R-12, except for the "probably" which doesnt instill a lot of confidence in me.

A sticker is supposed to be placed in an obvious place, like on the radiator support beam or the service ports, when a system is converted to 134. I would not bother topping off the system if you are not sure and just replace the belts.

Useful Aside: It's only 'Freon' if it is R-12 that was made by DuPont, just like it's only a 'Xerox Copy' if it was made on a Xerox Copier - it's a trademark.

Oh, and DuPont uses the 'Suva' trademark for their R-134a and other 'clean' refrigerants.

And 'Aspirin' is a trademark of Bayer A.G. for acetylsalicylic acid. But it started to fall into common use and Bayer didn't defend their trademark when it was infringed, so the courts ruled to turn aspirin into a generic term.

The different fittings only make cross-contaminating the AC System more difficult, but certainly not impossible. The bulk cylinders and can tappers can use the standard 1/4" Flare connection or the R134a Acme style connector, adapters and hoses between the two fittings are readily available, and a clever idiot can still mix things up.

Then you get the ones that "convert the system" themselves leaving the old R-12 fittings and no outward signs of what they did. You can use Propane or any of a few dozen alternative refrigerants in the system, depending on what you have on hand.

There are a half dozen different "Replacement" blends for R-12 meant for commercial and mobile refrigeration and appliances, depending on the design thresholds of the system you are refilling. Some are compatible with mineral oil, some aren't and require a flush and fill with PAG or POE based oils - which may or may not have been done...

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