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Dan M
Dodge Dakota
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6/09/2005
07:50:23
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 Subject: cost of A/C evac
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why does it cost so much to just evac an A/C system and why are people "surprised" when I call to get it just evac'd and not recharged? What? Doesn't anyone replace A/C components anymore themselves anymore?
Does it really cost that much to dispose of r134a?
I got quotes from a dozen places last night and the cheapest was $45 and most expensive was $99.95 (not a dealer!!). I spoke to about 5-6 places that will not just do an evac.
alot of those places that will evac it charge the same if they evac it as they do for an evac and recharge.
- Dan M
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nwf
Dodge Dakota
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6/09/2005
09:35:32
|  RE: cost of A/C evac
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They all have to use recycling setups, so what goes in must come out at some time.
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Dan M
Dodge Dakota
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6/09/2005
09:58:22
| RE: cost of A/C evac
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of course, but is the cost for the disposal/recyling of it that much?
Perhaps someone who does a/c work for a shop can expound on this for me.
- Dan M
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Big Ed
Dodge Dakota
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6/09/2005
12:00:23
| RE: cost of A/C evac
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Why don't you just vent the 134A out, its environmentally safe and cheap to buy. It was the R12 and 22 thats so "dangerous" (clorine). Why do you need to evac it anyhow?
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Dan M
Dodge Dakota
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6/09/2005
16:28:40
| RE: cost of A/C evac
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I had it appart to replace parts, i want to vac out the air/moisture before filling it back up.
- Dan M
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Big Ed
Dodge Dakota
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6/09/2005
20:56:34
| RE: cost of A/C evac
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If you live in S.E. Penna, I'll do it for you for free. I have a vacuum pump. (I'm an HVAC mech).
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Dan M
Dodge Dakota
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6/09/2005
22:15:36
| RE: cost of A/C evac
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I'm in GA. I think I know more about HVAC than the people at various shops i talked too.
shop - "we don't do the R134, only the R12."
me - "you mean you don't do A/C in cars built after 1995?"
shop - "Yeah we do, the R12."
me - "R12 is the old stuff, R134 is the new stuff".
shop "Oh then we do that."
- Dan M
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Big Ed
Dodge Dakota
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6/10/2005
08:17:19
| RE: cost of A/C evac
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All you need is a decent vacuum pump. Nothing special about it except the guage fittings on your truck. (kwik connects). Sounds like some of those places hire morons too. Theyre everywhere.
Sorry your so far away, maybe someone near you will read this post and can help u out.
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Bob Lincoln
Dodge Dakota
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6/10/2005
08:28:58
| RE: cost of A/C evac
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"Why don't you just vent the 134A out, its environmentally safe and cheap to buy. It was the R12 and 22 thats so "dangerous" (clorine). "
Wrong. R134a is also illegal to vent, and also contains chlorine. It's just a little less dangerous to the ozone layer.
Most shops probably won't evac only for two reasons:
1) They want the whole job. Many shops won't install parts that you supply, for instance - they want to profit on the parts and labor markup.
2) They worry about their reputation, and if the system fails and it is made known that "they worked on it", they don't want their reputation smeared.
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Big Ed
Dodge Dakota
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6/10/2005
09:38:40
| RE: cost of A/C evac
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NO CHLORINE IN 134A. NONE
Tetrafluoro ethane
134A is MUCH less dangerous to the ozone.
R12 = CFC-12, Dichlorodifluoromethane
Dichlorodifluoromethane Alternatives: Although production is stopped, pre-ban CFC-12 can still be purchased new in the box at approximately $500 for thirty lbs, but chemists are on the lookout for good CFC-12 alternatives.
CO2 is recommended to replace CFC’s for blowing applications21, but all of the refrigeration factors discussed above must be accounted for when looking for new refrigerants.
Currently, chlorofluorocarbons are being phased out and replaced with fluorocarbons. The idea is that if there isn’t chlorine in the molecule, then it won’t be able to destroy any ozone (giving an ODP of zero). However, the drawback is that C-F bond absorbs far more infrared radiation than even CO2 [8], thus these new fluorocarbons generally have a high GWP. Take FC-116 (C2F6) for example, it is emitted to the atmosphere by the Hall aluminum process and sports an atmospheric life of 10,000 years with a GWP of 95008.
The ideal alternative refrigerant has all of the properties previously listed, is non-toxic, has a low vapor pressure at the right temperatures, doesn’t destroy any ozone, and doesn’t absorb very much infrared radiation. This is a hard bill to fit, but chemists are up to the challenge.
According to SUVA, Dupont’s refrigeration division, the suitable legal alternative to CFC-12 is R-134a1, 8, 21. Both ODP and GWP must be kept in mind when looking for alternative refrigerants, and ideally both ODP and GWP would be zero. R-134a has a formula CF3CH2F and a GWP100 Years of 1300 [6,21] and an ODP of zero (it doesn’t have any chlorine to release). CFC-12 has a GWP100 Years of about 8500 [8, 21], so R-134a is probably a good trade in terms of environmental impact.
Hydrocarbons, such as propane, butane, iso-butane, cyclohexane, and cyclopentane have also been used as environmentally safe refrigerant gases after refrigeration process redesign21.
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Dan M
Dodge Dakota
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6/10/2005
11:01:21
| RE: cost of A/C evac
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Any suggestions for a vacuum pump and cables? I've seen alot of various companies making vacuums specifically for a/c.
I found one that i can use with a compressor (hefty one), which I do not have.
All of the parts have been replaced, i just need to vac the air/moisture out so i can fill it back up with R134.
- Dan M
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durango^
Dodge Dakota
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6/10/2005
11:54:44
| RE: cost of A/C evac
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you have to keep the vacuum up for about 20 min to make sure all the water vapors are out of the lines otherwise it will not work correctly. it is much easier for the shops to just right after that is done to take 2 or 3 min. and pump the new 134 in. its almost not worth you time to do it yourself. you will get much better results if you use a professional machine. the result in colder air.
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Dan M
Dodge Dakota
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6/10/2005
13:00:37
| RE: cost of A/C evac
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time isn't an issue for me. What vacuum do you use?
- Dan M
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Bob Lincoln
Dodge Dakota
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6/10/2005
13:14:59
| RE: cost of A/C evac
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You actually should evacuate the system for 45-60 minutes to be sure to get all moisture out. Typically you try to pull 29 inches of vacuum. Pumps costing $200 and more are capable of this.
The amateur, hack way is to hook up engine vacuum and pull 20-22 inches of vacuum for up to 1 hour. The system I did that on was converted in Aug 1998, still cools great.
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DSW
Dodge Dakota
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6/10/2005
13:51:57
| RE: cost of A/C evac
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You can get a $17 134a vacumm pump from Harbor Freight tools that runs off an air compressor.
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92475
I have the $9 vacumm pump below that I got years ago and never used. One of my neighbors borowed it and used it on his R134a system, though he had to monkey around a bit to connect it to his R134a system. I think the only difference between these 2 pumps is the $17 pump has the R134a connector included.
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952
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Big Ed
Dodge Dakota
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6/10/2005
14:50:07
| RE: cost of A/C evac
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Bob Linc is right on the 45-60 min. vacuum. Thats standard practice. Best to then wait and see if it holds the 29 inch vacuum before you recharge the system. Wait a good hour or so, a pinhole leak could take very long to show up.
durango is wrong bout it being "colder air", it'll be as cold as 134A at 35# back pressure will make it, regardless the way you evacuate it. a 15 to 20 deg split between return and supply air is a good measure of how its working.
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Big Ed
Dodge Dakota
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6/10/2005
14:50:49
| RE: cost of A/C evac
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Bob Linc is right on the 45-60 min. vacuum. Thats standard practice. Best to then wait and see if it holds the 29 inch vacuum before you recharge the system. Wait a good hour or so, a pinhole leak could take very long to show up.
durango is wrong bout it being "colder air", it'll be as cold as 134A at 35# back pressure will make it, regardless the way you evacuate it. a 15 to 20 deg split between return and supply air is a good measure of how its working.
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durango^
Dodge Dakota
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6/10/2005
15:10:00
| RE: cost of A/C evac
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big ed im not wrong most of the time all of the at home jobs suck and they wont come anywhere close to a professional system. it will make a difference in the coldness of the air.
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smarty
Dodge Dakota
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6/10/2005
15:16:00
| RE: cost of A/C evac
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durango, the a/c does not cool the air it removes heat and moisture from it.
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Dan M
Dodge Dakota
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6/10/2005
15:23:50
| RE: cost of A/C evac
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I saw that vacuum at harbor, but it requires a fairly beefy compressor. I don't have a compressor at all, but want to get one. I did alot of searching on the internet and found some ac vacuum pumps starting at $150, the average price is $200+ for the 3-5CFM range.
- Dan M
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Big Ed
Dodge Dakota
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6/10/2005
18:24:28
| RE: cost of A/C evac
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Wrong again Darango, The amount of vacuum has absolutly nothing to do with how cold the system gets. The coldness is the amount of heat trasfer from your evap. A good deep vacuum is desired to remove all noncondesibles (air, moister,ect)before adding the refrigerant. A system will work just as well without even evacuating it, but really not recommended. Some folk just feed refrigerant in the high side till it comes out the low side then add the rest.
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