stinsonbr

Just got a used ac compressor for my 2000 sport, and I was curious if I could fully charge it with a canister our two of the R-134a that you can buy from am auto parts store. If it wouldnt be cost effective then I will take it to a shop, but I really don't know how much it's supposed to hold. Any help would be great.

Brandon

xj_maniac_newb

I'm sure it'll work for a while, but it'll leak. You have to put a vaccum on it. From my understanding of it, the coolant should be at a somewhat "neutral" pressure. You can get a small vaccum pump and an AC gauge set for decently cheap, its not all that hard. However, the AC system we recharged on an 04 tacoma took 3 cans or so to full up.. so I'd go ahead and get more than you think you'll need.

rrich

"""""I'm sure it'll work for a while, but it'll leak. """""""

WHY WOULD IT LEAK?


"""""You have to put a vaccum on it. From my understanding of it, the coolant should be at a somewhat "neutral" pressure. """""

WRONG - THE VACUUM IS ONLY A TEST TO SEE IT WILL LEAK, AND IT REMOVES THE TINY BIT OF MOISTURE. It's under pressure!

xj_maniac_newb

Firstly, I'm surprised that 150 shot of caps lock didn't blow the welds off the forum. Are you yelling or something? Use your inside voice.


Second, if you have such extensive knowledge of AC systems you'd know you can't just full it up with a few cans, you have to get the air out of the system as well as like you said the moisture. Just throwing cans into your system can cause leaks from what I'm told, and won't net you as cold of air out of your AC system.

And didn't know thats what the vaccum was for, From what I've always been told the freon should be at a low pressure.. however I've been wrong plenty of times before.


Now for some useful information. heres a write up on it.

http://m.wikihow.com/Recharge-the-Ai...ioner-in-a-Car

car5car

Ask repair shop to use vacuum pump. You can charge freon yourself, if you know how to do that.
Pressure should be about 35 PSI, don' t charge more than that.

If shop wants $100, you can probably find used pump for that.

macgyver35

You should have a vacuum pulled so you know you're not wasting your time. Rebuilt compressors are known to have leaks right out of the box sometimes. If you are going to invest the money and time to replace the compressor, don't shortcut the rest of the process. Also, unless you do a proper vacuum and fill, you may void any warranty that came with the rebuilt compressor. If you have a bad unit and need to get it exchanged, the manufacturer may want a copy of the receipt from the shop that vacuumed and charged the system to verify that it was done properly.

Any AC shop can do an evacuation and fill for around $80. If they charge you much more than about $110 you're getting ripped, at least in Texas you would be. I got mine done by a guy with a small shop in Dallas for $75 and that included the freon.

Pulling a vacuum of at or near 18 inches and seeing if it will hold at the reading for at least 10 minutes is a good test for leaks in the ENTIRE system, including the compressor you just put in. It will also boil off any moisture in the system and remove any other gases (oxygen, nitrogen, etc) that may have gotten in the system. Once/if it passes that, he'll charge it. Assuming you start with a proper vacuum, your 2000 model should take a 1.25 pound charge. High and low side pressures during operation will vary with ambient temperatures, airflow through the condenser coil, and system load. In general, low side pressures between 40-48 are normal. There is a low pressure safety switch that shuts the compressor down if the low side pressure drops below 38 PSI.

You also want to determine if your new compressor comes with an oil/lubricant charge already inside. If not you'll need to add a few ounces of lubricant to keep that new compressor happy.

Seriously, pay the $80 and have it done right. I'd also recommend replacing the accumulator/drier as well. Rock Auto sells them for about $18. Just a little added insurance for your system.

rrich

The OP said in post #1- """""Just got a used ac compressor """""

Note the word "USED" not rebuilt, not new.
"USED" does not mean it has a warranty, nor does it mean it leaks.
USED is simply --- used.

Evacuating the system before filling is used to find out if it leaks - if any part of the system leaks - it won't hold vacuum.
But it's not to make the system hold any more coolant - try it - evacuate it, then add some juice. The difference in how much it holds total is less than 2 OZ.
The normal reason besides finding leaks to evacuate it is to get the little bit of air and moisture out of the system. Installing a "used" compressor one never knows if it's been stored where it's wet or not.

But - using vacuum to find a leak tells you that you have a leak, but not WHERE the leak is. To find out WHERE it is you can pressurize with air or nitrogen and spray soap around to look for bubbles.
Or use Freon. Freon is usually the easiest - then you can use an electronic leak detector. They are cheap nowdays.

But armchair mechanics that only know what the internet says are experts - I wish I consulted them before my shops did thousands of AC services. Geez - I wonder how we did it without their advice?

wjnfirearms

Ok, guys. Play nice.

Both of you are right in your own ways. If you want to do it by the book and absolutely correctly, macgyver has it correct. However, you can do it on the cheap and as many DIYers do with the caveat that you can possibly have issues with potential leaks and not getting all of the air evacuated out of the system. There's no guarantees with used parts. Used anything is a crap shoot if it will work ok or not. You do risk throwing out the money spent on the 134A if there are leaks in the system after the swap. And to do it absolutely by the book right, you also need to replace the evaporator and any orifice tubes in the system doing a compressor swap. Do many get away with not doing this? Yes, they do. To minimize the risk, make sure to replace the o-rings. They are sold at most auto parts stores and are not expensive.

You still risk money going to a pro because he will charge the system to check for leaks after doing the swap. The refrigerant isn't free. If he needs to charge the system and finds leaks, the system will have to be evacuated to do the repair and then charged again after. You get charged for two fills of 134A. Name me a pro that doesn't and I will sing his praises publicly. I don't know of any myself.

I don't know a whole lot of DIYers that have or can afford a halogen leak detector. The only reason I have one is that I stumbled across a used Snap-On at a flea market for $25 that actually worked and was in new condition. Maybe they are cheaper than before, but few DIYers have them still. Most DIYers that want to diagnose a leak themselves go for the dye and UV light that is affordable and many professionals use themselves. Again, sold at most parts stores.

Bottom line is that you do risk throwing money away no matter which way you go, DIY or pro. If you're confident in your abilities with a/c service, go ahead. Make sure you have what you need to do the job right, though. If you don't have a gauge for your recharge, get one. An undercharged system won't kick on the compressor. An overcharged system will activate the safety and the compressor won't work either and you risk blowing seals. And make sure you use PAG oil by itself or buy a 134A brand that has it in the mix. It's integral to an a/c system to use oil in the charge mix to operate correctly and to protect the compressor.

macgyver35

My bad. I failed to realize that rrich was participating in this thread. If I had, I'd have not said a word. It's just not worth the aggravation...

We seem to have a fundamentally different approach on how to tackle AC issues. I generally prefer, like a bajillion other people, to pull a vacuum. He prefers to make posts that insinuate that anyone that does that is an idiot.

rrich

A leak detector is expensive? About the same cost as many DIY refill kits. $20-$25.

If you can't afford one of these, how are you going yo pay a shop to do it? How are you going to afford the gasoline to get it to a shop?

http://www.ebay.com/itm/Freon-CFC-HF...item35ad0f5c50
Not just this one, there are lots of them offered.
These work great - and are even more sensitive than my $300 Snap-on.

Evacuating it is valid, but not always needed. if the system was never opened and still has freon in it - AIR OR MOISTURE CANNOT POSSIBLY GET IN! So it's not needed.
In this case it is - being used you never know if it was stored outside in the rain or wherever. So evacuating is appropriate.

Evacuating is not to make it hold more freon.

Yo Yo doesn't understand that.

It's not just a case of mounting it and charging it - the total amount of oil in the system must be checked - and the amount of oil in the compressor's crankcase has to be checked - they are separate.
Look up the make and model number of the used compressor on the internet - it will show how to check the oil in the crankcase for your compressor by making a simple wire dipstick. If it does not have the proper amount of oil in the crankcase it will only last a few minutes, then self destruct.
Adding oil to the rest of the system DOES NOT OIL THE CRANKCASE.

Yo Yo doesn't understand that either.

macgyver35

rrich,

Once again (even though you've been called out in the forums several times about your posts) you have resorted to insults and name calling.

I don't know if it's just your personality type, but you always seem to overuse quote marks, blast us all with caps lock on a regular basis, insinuate that people are stupid if they don't agree with you, and refer to others with names like ninnies, yo yo, etc. You even have a knack for using the term "shadetree mechanic" in a very derisive way.

It makes me wonder... Were you born with a grating personality, or was it something you had to work at?

At this point it's less a question of whether you are right or wrong, and more about whether you can contribute to discussions and engage in debate without insulting half the members. Seriously, how many times are other members going to have to tell you to tone it down before you take a hint?

Jeeze... I've been a member of numerous vehicle-related and IT-related forums for years now, and outside of obvious trolls, I've never run across anyone quite like you.

rrich

""""""""I've never run across anyone quite like you. """""""

And you probably won't either.

When you don't know something but you pretend to just to mislead people what does that make you?
I call the shots as I see them!

macgyver35

You just can't help showing your ***, can you? You call it like you see it, huh? Well, I'll refrain from calling you like I see you. I think you leave enough evidence behind in your various posts to make those things readily apparent.

Admittedly, I misread the original post where he stated it was a used, rather than a rebuilt, compressor. But, all things aside, tell me where I'm wrong and misleading people. What I recommended still applies whether replacing your compressor with a rebuilt or used unit. In fact, it could be argued that what I recommend is even more important when it is a used unit.

Nothing I stated is "wrong". It may not be how you would do it, but that doesn't make it wrong. I provided information that was accurate and that would be considered absolutely correct by any number of folks, certified mechanics or otherwise.

You simply can not say that me recommending that they pull a vacuum on a system is "wrong". It's not.

Pulling at or near 18 inches of vacuum and seeing if it holds for at least 10 minutes (sometimes as long as 20 minutes) is a time-honored methodology. It is not wrong.

Recommending that a vacuum be pulled after replacing a compressor to help remove moisture and trace gases is correct. It's not wrong.

The system needing a 1.25 pound charge is correct, assuming a vacuum is pulled. It's not wrong. It's right out of the factory service manual.

Verifying whether the compressor has the proper level of oil in it, and adding oil based on what you find there is the correct thing to do. It's not wrong.

Noting that there is a low pressure safety switch that kicks in at 38PSI is correct. It's not wrong. It's also in the factory service manual.

Noting that low side pressures will vary based on ambient temperature and other factors is correct. It's not wrong.

If you insist on being a troll, please choose another forum to share your brand of enlightening insights, charming diplomacy, and witty banter. The rest of us have had quite enough. Perhaps Pirate 4x4 would be a more fitting venue for your snide comments, insults, name-calling, and holier-than-thou attitude.

rrich

Misreading again I see!

Read my post #10 on this thread.

This is not the only time you've shown your ignorance and desire to mislead. On many other threads you've demonstrated your trait. This forum is here to HELP people, not trick them into replacing or doing things that won't help.

GROW UP!

RTorrez1

I'm Not taking anyones side here. But just a word of warning. I was Banned for a week because I made a comment about someone making a post in the wrong section and a newbie came on cussing like crazy. So they banned me and not the other guy. To this day I still have no idea why I was banned and not the guy that did all the cussing. Anyways, I just wanted to give you guys a warning that you shouldn't by going off on each other on here. After all we are all here to help each other out. And not everyone will have the same opinion on how to do things.