R134A retrofit advice needed

[Tony Hanna]

Just finished up a half-assed r134a retrofit on the sundance and it works, but not as well as I'd like. I'm getting 52-58 deg. duct temps on a 92 deg. day and I was wondering if this is about normal for a stock r12 system charged with 134a? Any advice on getting this thing to blow colder would be appreciated. If nothing else, I may dump the 134a and go with a hydrocarbon refrigerant like a propane/isobutane mix or something similar.
Thanks,
Tony

[turbovanman²]

Did you replace the reciever/dryer? that makes a big difference. Also, how much did you charge it with? I have done lots of conversions using 134 a and never noticed poor performance. How is the fan? is the condensor sealed to the rad so the fan gives it a good pull?

[Tony Hanna]

Did you replace the reciever/dryer? that makes a big difference. Also, how much did you charge it with? I have done lots of conversions using 134 a and never noticed poor performance. How is the fan? is the condensor sealed to the rad so the fan gives it a good pull?

Sure didn't. On top of that, I had to replace a hose, so it's been open to atmosphere and I have no way to draw a vacuum on it to get the moisture out. I just purged the system with about half a can before I started to fill.
I can't remember exactly how much I used, but I charged to 35 psi on the low side.
Out of curiosity, what have you noticed in the way of duct temps on a converted system?
Thanks,
Tony

[looneytuner]

Find a shop that will just pump it down for you after you install the drier. There have to be some old geezers like me that remember not having the money. You also have to drain the old oil and add 134 friendly oil.

[Boogieman142]

yeah, there is a tsb on this also. 134a runs a higher pressure than r-12 but r-12 cools better. I guess i got lucky and my r-12 system is still working(i can get the gas for it). If you want a cheap vacuum then find an old refrigerator/freezer and take the compressor out(make sure there is nothing in it) and hook up the right connectors to the vacuum side of it and attach a vacuum gauge for testing vacuum on a car. Thats what i did and it works great. Thats prolly half of your reason why it doesn't work. Our cars don't use the orifice tube style so air in the system is more crutial, they use the txv system, it varies a valve according to the temperature and because temp and pressure are porportinate of each other(70*=about 70lbs) it uses that, it is very accurite and does not need to cycle the clutch as much. If it is cycling the clutch a lot then it prolly has some air in the system. The oil that is in there from the r-12 will not mix with the 134a so you need to take all of that out and put in ester oil or you will have compressor failure. This is just a little on it, i hope it helps.

[Tony Hanna]

Find a shop that will just pump it down for you after you install the drier. There have to be some old geezers like me that remember not having the money. You also have to drain the old oil and add 134 friendly oil.

Right, I used esther (sp?) oil since they claim that it doesn't have any problem mixing with any residual oil left in the system.
I wonder if a compressor out of an old refrigerator would pull enough vacuum to draw down the system? I'm sure I could find one easy enough.

Anyhow, here's my plan. I'm going to run it as-is for now since it's still better than nothing. I've ordered some es12a refrigerant and when it gets here, I'll buy a new drier. Before I install the drier, draw it down, and charge it, I plan to completely flush the system. I'm curious to see how well this es12a refrigerant works. According to the advertising and some other stuff I've read, it's supposed to perform better than r12 does, so it should do quite a bit better than r134a. The only down side I can see is that it's a hydrocarbon and as such is flammable, but so is just about every other automotive related substance. If it makes the ac work good, it's a risk I'm willing to take.
I'm still curious to know if anybody has measured air temp at the vent vs. ambient after a 134 conversion? I'd like to know how far off the mark this thing is. I'm getting a 34-40 deg. drop with the ac on recirc. depending on engine rpm.
Thanks,

[Tony Hanna]

If you want a cheap vacuum then find an old refrigerator/freezer and take the compressor out(make sure there is nothing in it) and hook up the right connectors to the vacuum side of it and attach a vacuum gauge for testing vacuum on a car. Thats what i did and it works great.

That's awsome! You answered before I even asked the question. I was watching a movie and it took forever to type the post.
edit: While I'm thinking about it, which service port is used when pulling a vacuum? Low side, high side, or does it even matter?
Thanks,

[ottawa rogue]

shouldn't really matter. if you can, hook up to both the low side and high side
also, a refrigerator compressor won't generate as high a level of vacuum as a dedicated vacuum pump(especially if you have an old one), so leave it on for at least an hour, more if you can.
one other thing, they make a variable orifice tube for CCOT type systems to help with the cooling issues on retrofits.
while we don't have this setup on our cars, you might ask a parts store if there is an expansion valve made for 134a, maybe a later model part?

[Boogieman142]

in theory it doesn't matter what side you use to pull a vacuum but most people use the high side because thats the easier hose to use.

[Boogieman142]

our systems are a txv typeso they already have the variable orifice. a refrigerator will generate enough vacuum. An hour is about right that you want to pump it down, a little high tho. I do atleast 45min, you can do whatever you want, just make sure it is a perfect vacuum(depends on elevation but generally 28-31)

[Tony Hanna]

shouldn't really matter. if you can, hook up to both the low side and high side
also, a refrigerator compressor won't generate as high a level of vacuum as a dedicated vacuum pump(especially if you have an old one), so leave it on for at least an hour, more if you can.
one other thing, they make a variable orifice tube for CCOT type systems to help with the cooling issues on retrofits.
while we don't have this setup on our cars, you might ask a parts store if there is an expansion valve made for 134a, maybe a later model part?

Hopefully I won't need to worry about the expansion valve since I'm getting away from the r134a in favor of the es12a. Supposedly the es12a behaves enough like r12 that it will cool just as good or better than r12 with no modifications to the system.
Thanks,

[Boogieman142]

supposovely it will but just remember to make sure there are no leaks in it at all. Also make sure your compressor can handel it.

[ottawa rogue]

just caught your post on the es12a--DON'T USE IT!!!!!
if you happen to spring a leak in your evaporator core, there's a chance that you could turn the inside of your car into a barbeque. if you don't want to use 134a, try to find some Frigc or other non flammable substitute

i really think that if you flush out your condenser and evaporater cores(you can get away with using brake cleaner-just blow it out really good with compressed air), and use a 134a compatible reciever-dryer, you should be good. and see if you can get an expansion valve that is designed for 134a if you can.
134a is more sensitive towards charge weight, unlike r-12 if you overcharge it, it'll stop cooling.
i've got some conversion capacity charts, let me know what your R-12 charge weight is and i can get you a pretty close idea of how much 134a you should need
Bryan

[ottawa rogue]

our systems are a txv typeso they already have the variable orifice. a refrigerator will generate enough vacuum. An hour is about right that you want to pump it down, a little high tho. I do atleast 45min, you can do whatever you want, just make sure it is a perfect vacuum(depends on elevation but generally 28-31)

ya, they'll work ok, i had one i used for a few years until i finally broke down and bought a robinair
only problem i had is that i could never get more than 27" of vacuum out of it
that what i get for scrounging
wasn't really sure if chrysler had released a txv for 134a apps, it's been a few years since i worked on cars for a living.
do they still use the same part --- the r-12 apps?

[Tony Hanna]

Out of curiosity, how do you guys reccomend flushing the system?
Since it started out with r12/oil, and now has r134a/oil/stopleak, I'd like to flush all the crap out of it before I switch over to the es12a.
Also, how many oz of oil is it supposed to take once it's been flushed. When I did the 134a, I just put a bottle in it and figured that would be good enough, but I'd like to be sure and get the exact right ammount this time.
Thanks,

[ottawa rogue]

well, you can go out and buy a really nice flush kit $$$$$$, but that wouldn't be the TD way
or you can get a few cans of brakleen, spray them in the evap core and condenser and blow out the mess with compressed air
this actually works pretty good, just remember to blow the stuff out in the opposite direction of refrigerant flow and wear safety glasses(don't ask)

[ottawa rogue]

and on the oil, a couple of ounces in the condenser inlet and maybe an ounce in the evap inlet should do the trick, annd if you want to get really fancy, pull the compressor and drain the oil out of it.
if you put any oil in the compressor, just remember to turn it over by hand 20-30 times to make sure it won't lock up

[Tony Hanna]

just caught your post on the es12a--DON'T USE IT!!!!!
if you happen to spring a leak in your evaporator core, there's a chance that you could turn the inside of your car into a barbeque. if you don't want to use 134a, try to find some Frigc or other non flammable substitute

i really think that if you flush out your condenser and evaporater cores(you can get away with using brake cleaner-just blow it out really good with compressed air), and use a 134a compatible reciever-dryer, you should be good. and see if you can get an expansion valve that is designed for 134a if you can.
134a is more sensitive towards charge weight, unlike r-12 if you overcharge it, it'll stop cooling.
i've got some conversion capacity charts, let me know what your R-12 charge weight is and i can get you a pretty close idea of how much 134a you should need
Bryan

I really need to type faster. You guys are answering all my questions before I even get the chance to ask them...
As for the flamability risk, I'm willing to take it. In order for something catastrophic to happen, it would have to leak inside the passanger compartment in enough of a volume to create an explosive atmosphere before it could dissipate which would take a pretty sizable leak. It just doesn't seem very likely to me. What seems more likely is the stuff igniting due to a broken line or condenser in a wreck, but that would be underhood which would put the firewall between me and the flames. Add to that the relatively small ammount of refrigerant in an auto ac system, and I just don't see it being much more dangerous than carrying a couple cans of hairspray in the car.

[turbovanman²]

DO NOT Flush the system, its pointless and unless you had a compressor blow bits into your system, your just making things worse. Only add enough oil that you took out, so if you replace the reciever dryer, add like 2 oz's then add another 1 oz as when you pull it down, you loose some oil. The old R12 oil is fine, when left in the car/van. I also like to pull a vacuum down for around an hour. When I get my van running again, I'll take some temps.

[ottawa rogue]

I just don't see it being much more dangerous than carrying a couple cans of hairspray in the car.

Dude, i really don't want to know