A/C Refrigerant Upgrade??

[capeclassics]

I have a dealer installed underdash A/C unit in my 70 Sport Custom.It's probably time to upgrade to R-134(?) refrigerent.What exactly is invoved in doing this correctly??
Thanks

[71PA_Highboy]

Google is your friend:

http://teamchicago.com/imperial/imp-ac.htm

[sargentrs]

Correctly? I don't know all the particulars but the quotes I got ranged $450-$700. This involves, I think, changing drier, condenser, hoses, o-rings, fittings, drain, evacuation, recharge, etc. With that said, I took mine to a local a/c service shop and he said wasn't necessary in many cases. He drained, evac, and recharged my R-12 '90 Toyota Camry with R-134 a year ago and it's been blowing cold ever since. It may be doing irreparable damage behind the scenes but for the past year I've had no issues. To me a/c is optional so if it craps out I'm not overly concerned.

[basshound71]

R-134a uses a different oil that does not mix with the r-12 oil. In turn when you switch to 134 it will ruin any gaskets that have had contact with r12 and its oil. It will require a different thermal expantion valve. You will need to replace the dryer. 134 is more enviromentally friendly but that only matters if it is leaking. If your r12 unit is not leaking and cooling fine, leave it alone until it doesn't. There is no need to change it for the hell of it. 134 will not cool quite as well as r12 especially at idle as it runs a higher discharge pressure and temperature. It is a good alternative or at least the best one out there at this time. There are better refrigerants out there but are not compatable with the required oils for automotive compressors.

[basshound71]

In short, if it ain't broke don't fix it

[fireguywtc]

I disagree with going with R-12 if the AC needs charging, unless you have cheap access to it. I agree that it is a superior refrigerant, especially for our AC systems. When I retrofitted my 70 I was quoted a ball park figure of $150-200 for charging with R-12 (just the refrigerant). R-134 is significantly cheaper and works fine, I would think in Massachusetts it would be more then enough for their summers.

When I retrofited my AC system I needed everything new except the evaporator. I had it checked for leaks and cleaned. I put a larger condensor on my truck. I needed new lines, seals, compressor with clutch, and dryer. I did all the work but running the lines and charging the system. The shop also put the R-134 fittings on the valves of my compressor. I also heard that seals will need to be replaced when chaning over to R-134. I did not change the expansion valve but I would recommend doing it while you are changing everything over.

Overall I have been trying to figure out if my AC system is working properly. For right now it seems fine but will run all the time and never cuts off but cools pretty good. I have even froze my evaporator once this spring. I think if you can get your system switched over and working properly you will be able to cool your regular cab pickup quite well.

Here is a thread of mine worth viewing about some of my problems:
http://w.fordification.com/forum/viewto ... a&start=15

[FomocoLoco72]

All I did was add some of the new PAG oil and charged mine with R134. That was almost 10 years ago. The only part that really SHOULD be changed is the reciever/dryer and make sure you use the new style oil. Ive done a bunch of conversion on cars and the dryer is the critical part to make it work correcly/cool.

[basketcase0302]

I have even froze my evaporator once this spring.

Umm Bill, it aint' suppose to do that.

[fireguywtc]

I know, that's why it is still a work in progress. It froze in 80 degree weather with the fan on low. It usually never gets the opportunity to do that around here. I think it might need an expansion valve and low temp switch.

[basshound71]

Probably do to the wrong expantion valve. I agree if it needs recharging then update it to 134 but if it is fine then leave it alone. Any time you open any refrigeration system you should change the dryer and most of the time when you change refrigerant you MUST change the expantion valve to make it work properly.

[fomocoguy]

I have a dealer installed underdash A/C unit in my 70 Sport Custom.It's probably time to upgrade to R-134(?) refrigerent.What exactly is invoved in doing this correctly??
Thanks

For the record, I wouldn't call it an "upgrade" to switch to 134a. I've never had an a/c system that was originally designed for r12 turn out better or more efficient after converting to 134a. I found a great replacement refrigerant for r12 AND 134a that is a direct drop in, gets colder than either one, only requires about 30% the amount of freon, has less drag on the compressor, and is perfectly legal and affordable. It's called ES-12a and it's made by envirosafe. Check it out: http://autorefrigerants.com/Envirotechnical.htm It's a hydrocarbon and you need to do your own research and decide if it's right for you, but I used it in an old Fairmont I owned awhile back and with nothing more than pulling a vacuum and dropping a few cans of ES-12a in her I had colder a/c than any of my newer vehicles.

[fireguywtc]

I believe all of the stuff that is in the link you provided is true Joe. However, they are advertising their product and will likely omit information to sell their product. One of the crucial pieces of information that I have noticed missing is the upper explosive limit (UEL) and lower explosive limit (LEL). These are the limits which define when a product is too rich or too lean to burn or when the mix will combust. I suspect that limits for any hydrocarbon based refrigerant would be in a range that is dangerous for automotive use.

Here is some more info. on the subject if you want to read about hydrocarbon refigerants. They are outlawed in several states for a reason.

http://www.google.com/url?sa=t&rct=j&q= ... 24kid0BF5Q

http://www.epa.gov/Ozone/snap/refrigera ... ng.html#q5

http://www.autoacforum.com/messageview. ... adid=21716

[fomocoguy]

I believe all of the stuff that is in the link you provided is true Joe. However, they are advertising their product and will likely omit information to sell their product. One of the crucial pieces of information that I have noticed missing is the upper explosive limit (UEL) and lower explosive limit (LEL). These are the limits which define when a product is too rich or too lean to burn or when the mix will combust. I suspect that limits for any hydrocarbon based refrigerant would be in a range that is dangerous for automotive use.

Here is some more info. on the subject if you want to read about hydrocarbon refigerants. They are outlawed in several states for a reason.

http://www.google.com/url?sa=t&rct=j&q= ... 24kid0BF5Q

http://www.epa.gov/Ozone/snap/refrigera ... ng.html#q5

http://www.autoacforum.com/messageview. ... adid=21716

LEL is 1.9%, UEL is 8.5% according to the MSDS. Not sure if that's good or bad, but you're better suited to answer that question than me. All I know is my experiance with the stuff and a lot of good experiances that I've read. I also have to say that of all the things I've read on boards where professionals say "no way, don't do that" I have yet to find an article about a vehicle exploding or catching fire due to ES-12a. "Professionals" hate the stuff because if not labeled properly a vehicle with any hydrocarbon refrigerant poses a risk to them, as a system evacuated into their R12 recovery tank will contaminate the whole tank and cost them a substantial amount of money. I personally believe that drives most of the negativity toward the stuff.

[fireguywtc]

Perhaps that is where most of the negativity comes from, but I see most of the opposition coming from the risk of having the hydrocarbon based refrigerant in the auto. There are probably few to no cases of accidents because there are so few people using them. There would be no explosions really, just fires started from the stuff. Additionally, most of the risk comes from something happeing such as a signficant leak or getting in an accident that causes a leak.

These events are rare and most people could likely get away with using the HC refrigerant with no ill effects. But eventually, someone will create the right environment in which a fire will start that wouldn't have with CFC based R134a. The LEL and UEL of ES-12 is similar to other hydrocarbon materials such as gasoline and propane. The range is relatively small (less then 7% range) but a leak to meet the minimum 1.9% would be pretty easy to achieve.

[SecondCamperSpecial]

If r12 is available I would use it. R134 uses higher head pressure and you really need an electric cooling fan for it to work right. That can be wired but at what cost. As long as I have r12 I am keeping all my vintage vehicles using it. If you are handy and can wire a fan to come on with the compressor than it will work.