Innovation

iTrader: (1)

I;m going to convert my A/C from R-12 to 134A. Does anyone have feed back on this? What parts did you need? Did you have any problems after you did it? Does the system have any problems with the additional head pressure with the 134A. The old A/C in Florida ain't getting it anymore. R-12= $70.00 a pound.

inflatablepets

First evacuate the R-12 from the system. If it's already empty, then don't worry about this right now. If the system was left open you need to replace the accumilator with a new one. It's the thing with the sight glass on it. That will run about $40. Then try to remove as much oil from the compressor as possible. I use brake fluid and compressed air to do this. Puor a couple ounces of PAG oil in the compressor. Then seal the system up replacing any possible leaking o-rings. Get a vacuum pump and pull a vacuum on the low side as much as possible. You should be able to pull at least 28 inches of mercury (on the gauge of course) Then charge the system to 80% of system capacity. It will be about 2 cans of R-134 A.


Good luck and if you have any questions, ask.

Johny zoom

iTrader: (5)

If it was left open change the TXV. I just got mine going again but used 401a (hotshot ) refrigerant. and yes this stuff was expensive when I bought it a couple of years back


Johny

jackhild59

iTrader: (7)

If I were you, I would pay the $ for the R12 after thoroughly leak checking the system. I am in Dallas, so our heat and humidity are similar to yours. Maybe a little less humid and a little more heat.

I replaced my compressor last year due to a bad compressor clutch. I am as cheap as anyone else, so I tried the alternative ES12/duracool. This is basically hydrocarbon based which means PROPANE and BUTANE. What the hell, it's a rotary and all those Honda dudes think it's going to explode anyway....

...anyway, the HC stuff works well and has great temp and pressures- at temperatures that I don't need A/C. Once the temps get into the high 90's and the humidity climbs, the HC stuff doesn't have the system capacity to keep up and the system cools down slow while running high pressures on the low side. That means high vent temps. I tried adjusting the charge etc and it wasn't worth a damn.

I have 8 left over cans that I will sell for $6 per can. Shipped if you buy 2 cans. It doesn't work worth a damn, but you can try it too.

So I tried the R134a route. Now everything worked better. The system had much better cooling capacity, but ran high head pressures on the high side. It was a *very* noticable drain on the power of a N/A rotary. It basically sucked. It is also hard on the compressor. I know that I could add a parallel flow condenser and an auxilliary fan on the condenser and that will solve the high pressure issue, but now I am going to spend maybe a couple of hundred dollars to have a system that is still not quite as good as it was originally designed.

So I decided to spend my $ on R12. The system now works just as intended. Last week we had some 100*+ days and I drove all day, starting and stopping, getting in and out of the car. The system performed beautifully and pulled down very quickly . I stayed cool. My vent temps would get into the mid 30's with the fan on highest setting. It doesn't get any better than that.

Good luck and if you decide to retrofit, at least add a highside cutoff switch to protect your compressor.

http://www.ackits.com/merchant2/merc...t_Code=57807MD

if not a parallel flow condenser.

http://www.ackits.com/index.cfm?fuseaction=Parallel

Good luck.

Jack

'89Vert

Our smaller compressors don't handle R-134a well. In short, your a/c will not be nearly as cool. Yah the R-12 is expensive, but if your system is working properly (e.g. no leaks) you're not gonna be doin this more often than once every three years. For more tips, visit the archive a/c thread, which I'll post the link for. Good luck whatever you decide.

A/C Thread

tinvestor

I owned a restaurant and I used hotshot 401a it is a drop in R-12 repacement (this means you do not need to change the type of oil for the compressor) and I am an HVAC Tech/Installer and the pressure differencs were negligeable on my systems however they were on larger capacity systems so I cant say for certain how this refrigerant would perform in our smaller system. The pressure differences I would think would stay the same.

By the way "open" as in, "if your system was open for a while then replace the accumulator" does not mean large hole or disconnected component it means empty. Open = open to atmospheric pressure = empty. Also if the system was not operating for a season or more OR if you go with R-12 just buy new O-rings and put them in I think there are 10 of them? 2 at fire wall 2 at compressor 2 under compressor fittings, 2 at accumulator, 1 into condensor, 1 on passenger frame rail. Dont forget to oil them with the proper oil for the refrigerant chosen this will take about an hour and is insurance to prevent you from paying for more refrigerant next year when the same leak continues leaking. If changing refrigerant to one that is not a drop in replacement for R-12 then change the accumulaotr anyway.

To me R134a is not an option. It operates properly under pressures that were not designed for our compressors to operate at peak efficiency. I reccomend drop in replacement or bite it and use R 12

Icemark

Ahh, HC based coolants have the same flash point as freon based refrigerants... do a little research before posting crap like that next time instead of listening to the air conditioning shop guy that wants to rip you off.

BTW, R134a... Clorofloro Carbons... How do you get Floro Carbons??? From cracking Hydrocarbons

Innovation
Frezze 12 is a R134 based refrigerant, that has special oils and polymers in it to make it compatible with both R12 and R134 systems. It is radically superior to any other refrigerant that I have found. Run it at 110% volumn over R134 based systems, and at 100% on R12 systems.

And the only things you need to change if you still deciede to waste your money on R134a, is the O rings and have the system purged of any old R12 oils.

'89Vert

Amen Icemark. Several of us in AZ have made the switch to Freeze 12 with success. And yah...it's hot here, we should know.

Innovation

iTrader: (1)

Thanks for the response. The system is not open and still works but not very well in the Florida heat. I think I'll try the Frezze 12 first and see what happens.
Can you just add Frezze 12 or do you have to pump out the R12 first?

jackhild59

iTrader: (7)

If you want really, really good a/c help try this link:

http://www.autoacforum.com/categories.cfm?catid=2

This is the most helpful site I have ever seen for repairing anything. The moderators are M-HVAC pro's or retired pro's. The site is run by a company in arizona that sells parts. Thier quality is high and so is thier integrity. You will never get flamed or called a noob or anything like that on that board. They will walk you through everything you need to know. They do not promote Freeze12, but neither do they pick on you if you use it.

Good luck

jackhild59

iTrader: (7)

It was a joke, Mark, and a pretty transparent one at that. The HC's just don't work worth a damn. R134a sucks for lots of reasons. I agree with you that Freeze12 is the best alternative. I have been down all the roads, including freeze12, autofrost, HC's and 134a. My point is that R12 is still the best choice for me and is a very valid choice for other non-molested systems. That's all that matters in this thread.

BTW, I sent you a pm that takes our discussion a little deeper, but is not germain to helping Innovate with his situation.

MaxRX7

I went with 2 cans of Freeze-12 after installing the compressor back in the car and it's working great so far.

Icemark

Good Idea, and sorry I called your comments crap... that was rude of me.

arghx

iTrader: (3)

A friend of mine used to be a mechanic for a living and has done a ton of R134. He's pretty skeptical of freeze 12. He's not convined that all the "other stuff" in there really makes the R134 compatible. I don't know all the reasoning behind it, but another friend of mine who goes to the Nascar Tech school in Statesville, NC is of the same mind. I can't fully debate the merits of this argument but I trust their judgment.

If I were all of you I would always change the receiver/dryer. It's usually like $40-50 or something. The stock ones are not compatible with R134... the desiccant (which is the **** that dries the air) can form toxic stuff when it comes in contact with the R134, which will eat your compressor seals.

SureShot

I resurrected an open AC 3 years ago using freeze12 professionally installed.
The acumulator was replaced, but all the other components are original.
I lost about 6 oz last fall, but it's still working well this summer.

HAILERS

It's summer already? humor

MaxRX7

haha, good one

Innovation

iTrader: (1)

Thank you, I found exactly what I was looking for on the A/C forum.

jackhild59

iTrader: (7)

That is a really good point. The detail is that the dessicant is ok with the 134a, it is the dessicant bag that is incompatible with the 134a compatablteoils. The bag dissolves and the dessicant scatters through the system clogging up expansion devices, grinding your compressor into a box of mush and contaminating everything. I always replace the drier if a system has been open to the air for anytime whether I am converting it or not. I consider zero pressure to be open to the air.

All the new reciever driers are manufactured are made to 134a compatible specs and have been since the mid 1990's. Of course they are backward compatible with R12 and all of the other stuff out there. It is the pag and ester oils that dissolved the bags.

Innovation

iTrader: (1)

Thank you to all that responded. I was somehow cut off during my post and didn't get the ask the cooling issue.
I have noticed lately that my temp gauge has been creeping up lately. When I run the A/C I'm hitting 3/4 temp on the gauge and confirmed it with a thermometer that I am running 212 degrees. I cleaned the radiator fins and condensor and added water wetter but this still concerns me. I'm thinking about replacing the water pump, thermostate and flushing the entire cooling system. My 7 is completely stock and I'm considering adding an E-Fan. Any feed back?

jackhild59

iTrader: (7)

How and where did you measure with what kind of thermometer?

Before changing anything, do a full cooling system tune up.

Check your pressure cap. replace only with Mazda oem.

Same with the thermostat. Mazda oem only. Aftermarket t-stats are reputed to cause rotary death.

Check your fan belt. Replace it if you have not yet done so.

Replace the radiator hoses.

Check your cooling fan clutch.

Back flush the radiator.

I have no experience with the water pump failing to pump coolant, even when it is beginning to fail (leak). Maybe others here have other experiences with water pump on FC?

The FC cooling system is very very robust. Efans are not noted for cooling better than the stock, just noted for giving lots better working access to the engine. http://www.aaroncake.net/rx-7/efanmyth.htm

If your car is overheating, something is not working right. Fix the problem(s) first. If your thermostat is not functioning properly or the radiator is clogged or the lower rad hose is collapsing and about to burst, you will be wasting your time with the e-fan, water wetter and all the other bandaid fixes. Your engine is at risk.

Dinnercoat

E-fans are basically good for two things.
1)Your stock fan breaks
2)You want more room in the engine bay

Like jackchild59 said if you're overheating you need to find the reasons why and address them.

NeCr0mStR

iTrader: (3)

I was told buy my A/C guy that R-12 is the way to go with an R-12 system. and based on what I know about R-134a its not any better for environment and therefore no justification to change over.

Dinnercoat

Well r12 is like $100/lb and r134a is like $3/lb. However from what I've been reading autofrost seems to be a good substitute. Its compatible with r12 systems, is compatible with the oils in the system and appears to give colder vent temps than r12 even (at least on the car of the guy who was tried it over r12) so may want to look into that. Icemark seems to have excellent success with freeze 12?