MACH7

Any success stories converting your a/c from R12 to 134a?

Metallic_rock

wal mart, Napa, Motion, Kragen, Schucks.... they all carry the conversion kit. my suggestion would be to open your system, suck all the R-12 out first, using proper reclaiming procedures. (I'm EPA certified... yada yada..)

Anyway, we all know you won't do that, so, when there is no more R-12 in your system, hook up a vacuum (a vacuum cleaner will work) to your system for an hour or so to suck as much crap out of the lines as possible. Use one of those little parts that are used for sucking stuff out of corners- one with a small tube on the end. While the vacuum is still on, go ahead and close the valve. Once you have the kit, and you have put the adapters on, just follow the instructions on the kit.


I have not yet done this on my Rx-7. I did it on my Jeep, and I do it at work. I can't see it being much different on the Rex.... I'm not sure if there is even a valve on the A/C system on the Rex... I'll have to take a serious look. The above info is generic for all A/C systems.

tmiked

A vacuum cleaner really isnt enough to give the AC system a good sucking.

If you cant find a vacuum pump, using engine vacuum works. A check valve will make it much easier, as you can trap the high vacuum when you rev and then back off.

Metallic_rock

I'm just giving info for people with low cash and standard home appliances. You're right, using a home vacuum isn't the greatest way to do it, but it will be better than nothing. according to the instructions on the R134a conversion kit, you don't even have to use the vacuum, but I recommend doing it, anyway.

Metallic_rock

Oh, and also, you don't want to have to sit there holding a vacuum line from your engine for an hour... (recommended time... again, not 100% necessary)

mar3

iTrader: (8)

However, both are low-buck great tips...thanx, guys!

MACH7

Good information, thanks - But has anyone made the conversion, say a year ago and is still happy with the conversion, e.g. vs. paying the price and keeping R12? - in other words, would you recommend doing the conversion from positive experience or staying with R12?

metallic_rock, you indicate you have done this to other vehicles you own - was this done awhile ago and are you still happy with the conversion? Plus you indicate you do it at work, are the customers happy several months later?

I keep thinking about doing the converison, but do not want to regret doing it and when I ask I usually get feed back from someone who has just done it, e.g. vs someone who has lived with it through at least one summer.
Thanks

enigma32

I also have been considering doing the conversion and have held off for much the same reason as MACH7.
And while we're on the topic,

[hijack]
What (roughly) does it cost to do the conversion?
[/hijack]

fatboy7

They usually have kits that include the coolant for around $30. I've had good expirences with the conversion on several cars, some of them have come out unnoticably worse than the R12. Unforunately, I've done it on two rex's and haven't been impressed with the results. It seems that the R12 system combined with the large solar load that is placed on the car was barely adequate. It's a car that has alot of window surface open to solar radiation.

When I've converted to R134a in the rex, the lowest temperature that I've gotten to come out of the vents has been around 60*F, when on max AC, and the rpms held at 2500. IMO (based upon expirences with newer R134a, and older R12 systems), the blower outlet temp when on max AC under the same conditions should be spitting air out at around 40*F. I think the draw through ventalation system was leaky, so the outside air may be a source of contamination.

The result is that it takes forever to get the car cool, if it ever does. Right now in UT its been around 102*F, If the sun is shining (which is most of the time), the car just doesn't get cool enough. After around a half hour of driving, It will stabilize around 85-90*. Thats still too hot IMO. If there is cloud cover then it drops to a more tolerable 75-80* which is fine. If the outside temps are below 90*F then it works fine even if the sun is shining.

My Prognosis: If you want you AC to work with R134a, you definately need to tint the windows.

They've actually done research on the effects of window tinting on interior temps. With no tint, at 110*F day in AZ the interior temps in a typical sports car (large raked widows... ie our hatch) the temps rose to 145*F in the car during the time when the solar load is the highest (2-4pm). By putting on 50% addmitance absorbtive tint (non-reflective), it dropped interior temps to around 130*F. Once the car was started and the AC working, it would take half the time to get to 80*F than without tint.

On a side note, reflective limo tint (3% admittance) dropped the interior temps to within 2-3*F of ambient at all times. It was like the sun didn't exist. Reflective was about two times as good at keeping the heat out than absorbtive tint.

I'll have an oportunity to fill my AC system from scratch here in a bit. Hopefully, that this time I'll have better results on my 7.

RXTbone

Make sure you have removed all, or as much R12 as humanly possible. I was warned by a mechanic that R12 and 134 create a gumming affect that will seize the compressor. I figured he was trying to gig me for $150 bucks, so I did the conversion myself. I made the mistake of just releasing the R12 on a '72 Cutlass, then loaded up the 134. About 1 week of use lead to a seized compressor that I had to replace. Whether that was the culprit or not... Just something you may be aware of...

Rx7carl

I agree, I havent been impressed by the 134. Had it in for 3 years now and its not as nice as the R-12 I used to have in my other 1st gen. It gets hot here in FL and I need to get the windows tinted. Its just not as cold as 12 was.

FuLLsMoKe

I'm currently changing a busted hose out and then converting (unless I can find someone that still has some of the good ole freon left). I've heard bad things about 134a... Just not cold enuf... But--I've heard many different stories about converting.

One guy said that it is highly recommended to replace your compressor because the 134a has a different lubricant in it from the old freon (this lubricant lubes up your compressor). He says this is because one of them is polar and the other is non-polar (not sure which is which) and thus the two will be like oil and water so a different lubricant is used. I really don't know if all of this is true... Can someone clear this up for me?

Another person told me that I can get something called Freeze-12. It's new stuff but hard to get ahold of and EXPENSIVE (up to 60 bucks an ounce). Anyway, this stuff is supposed to be almost completely compatible with the old freon.

A mechanic gave me a price quote on filling my system with the new stuff that's compatible with the old freon (after I replace the hose). His quote came to about 200-250 bucks. I assume maybe 100 of this goes to labor. So maybe this mechanic sells it real cheap or somethin?

As you can see, I'm all mixed up with this crap. Like me, I'm sure other people would like to know the correct answers to this

Much appreciated,
FS

MIKE-P-28

iTrader: (1)

i converted mine and it worked fine, i recommend changing all the o rings at all fittings too, the accumulator, and then replacing with 134 and 134a oil. A high quality vacuum pump is neccessary for this as is a recharging guage set.

A side point at Toyota where I work they have a machine, that sucks and fills, the trans fluid, the brake fluid and Ac in 77 seconds wonder what that costs, a good vacuum pump takes an hour or so

bliffle

I did quite a bit of reasearch on this last year (the commercial bus companies have the best research) and the bottom line is: don't switch. R12 will be available as long as we can keep our old cars running: it is the best coolant. Look for an oldtime radiator AC guy in your town, who has the license for R12. I found the guy easily and it cost me $170, which I figure is a good deal for effective AC and trouble-free operation.

B

MACH7

More good information, thanks
So if you do it right, the main negative effect is less effective cooling? I was also worried about the switch resulting in damage to the compressor and other components. So am I correct in assuming that if I have the switch done right by a qualified shop, the resulting change will not cause other mechanical problems with the a/c components? e.g. I do not want to think I am saving money on refigerant refills only to spend more replacing damaged components.

82transam

iTrader: (18)

I did the halfassed conversion. I work at a gas station so my boss sucked all the 12 out, we put the 134 fittings on teh compressor and filled it. Presto A/C works. its been like a month and it still works good too.

mwpayne

I just got back from the shop. I put a used compressor on (mine was leaking), they pulled a vac and filled it with 'freeze 12'. The shop said on older cars with residual R-12, it's best to use this as it mixes well with R-12, unlike R-134 wich can cause damage (so I've heard).
It is slightly more expensive than R-134, but a fraction of R-12. Seemed to be the best choice for me. Cools very well so far.
Cost for everything was $140.00, plus the $20 I paid for the compressor.

Metallic_rock

The ones I have done work perfectly... they don't get nearly as cold, but for the money, it is not worth it to even attempt getting R-12 ($65.00 a quart, last I checked)

RXTbone

I just passed up a $15 can of R12 on eBay, where it appears you can get cans for about $20 - $25. The listings require you to provide an EPA license if you win (Ebay policy requirement, like that matters). Has anyone bought R12 from eBay and NOT been required to present this license? I suspect most sellers don't even ask for it. Or do you know someone currently in prison, apprehended and prosecuted by the Ebay police?

Metallic_rock

it's still cheaper to convert to r-134a, and you don't have to worry about police or EPA certification.

RXTbone

Maybe I'm missing something, but how's that cheaper? A conversion kit would cost at least $35 bucks, plus you run the risk of damage if the system is not properly flushed. Let alone the fact you have to replace O rings, couplings, R134a doesn't produce as cold air, etc...

RX-7_ZX-9

I just had my FD recharged with FREEZE 12 and total cost was $56 with tax. That included price of 2 cans of freeze 12 @ $10 each. They're $6 each at NAPA but they won't sell it to you.

RXTbone

Can you mix Freeze 12 and R12?

RX-7_ZX-9

Supposely it's ok to. It was made as a cheaper alternative to R12.

RoyFifo

No.


I used freeze 12 on mine as well but have no idea how well it cools in comparison to R12 in my '7 (AC was dead when I got it). It does fairly well. On MAX AC, The outlet temprerature is about 36 degrees on an 85 degree day, but it takes forever to cool down the cabin. I have not measured the inlet temp behind the glove box, bit will do that soon.

But, I did do a 134a conversion on an 82 Caddy. The 82 caddy has about 50% of the cooling capacity now than it did with R-12.
I Went with Freeze-12 on the '7 because I did not need to install a High side pressure cut off switch which you need to do for a 134a conversion.