Air Conditioning Coversion

[Threehz]

Hello!

It is summer, as we know best down here in Tucson. Temperature has already exceeded 110 degrees and AC becomes pretty important to most people. My '77 280Z appears to have come with a stock/dealer installed AC system. All the R-12 was long gone when I bought the vehicle, but the system appears to be very intact still. The problem with R-12 is it's availability and price, not to mention environmental effects. I've recently realized how easy and inexpensive it is to convert an R-12 to an r134a system (in fact cheaper than an R-12 charge-up in many cases). Since my dashboard is out of my Z, as well as everything in the engine bay, I decided I have the perfect opportunity to explore the best way to do an r134a conversion.

I searched for any well-documented cases of this conversion and couldn't find any (if someone knows one, please share). I plan to find components that can be sourced new, and will fit with as little modification as possible in our Z-cars.

To do a proper conversion in our Z-cars we need the following parts:

Condenser (parallel flow)

r134a expansion valve

r134a pressure switch

Dryer/Receiver

PAG oil

I'm not sure about a compressor yet. The original compressor should work fine though (an r134a compressor will however work much better). This also assumes that the car already has an evaporator (if it is in good condition, it will work with either system). We will very likely need an auxiliary electric fan in front of the condenser (this is especially important to keeping the AC working at idle).

Now I figure that we can source these parts from later Nissan (or other) models (which had r134a systems stock) such as a 240sx or sentra. I also remember hearing about Honda compressors working for our Z's, but I'm not very clear on the details.

Anyhow, first thing I want is to find a list of parts that will fit nicely into our Z-cars for this conversion (or full AC system build). After that I'd like to put together a full guide on how to do the conversion/build.

So, if anyone has parts that fit, have already done a conversion, or has any information that will be helpful, please post away!

Thanks,

Kai

[Wade Nelson]

You're way overthinking this. In many cases an R134 conversion only requires replacing the charge itself.

Start by reading THIS thread. http://www.classiczcars.com/forums/thread45820.html

[Carl Beck]

You can convert a older R-12 system to R-134a. When you do, one of the first things you will find is

that the R-12 system will lose about 20% of its original efficiency. The next thing you will notice is that

the R-12 rubber hoses if not already the shielded type {and most were not} - will seep/leak R-134a, and any connections that are not O-ring sealed - will also leak R-134A.

R-134a ran in a System designed to run it - is just as efficient as the old R-12 Systems were. However there are significant differences between them in terms of their actual component parts. R-134a has a smaller molecular size than R-12. While it may seem ever so slightly smaller at the molecular level - it makes a lot of difference. For that reason R-134a systems use both condensers and evaporators with smaller diameter tubing, and longer lengths of it. R-134a systems are designed to use shielded high pressure hoses so the R-134a doesn't leak though the rubber hose walls. R-134a systems also use O-Ring'ed fittings {and double O-Ringed in some cases}.

In the 90's - Nissan provided a R-134a upgrade guide - in which they told the Service Personnel what all had to be changed when upgrading the Z32 R-12 systems to R-134a. Makes for some interesting reading.. In effect they had to change out everything except the compressor.

Personally - I would first make sure my present R-12 system is brought up to factory standards - In effect - make sure you have no leaks. Install a new receiver/dryer and suck the systems down to a vacuum for 24 hours.. The refill it with R-12. Most of my R-12 systems have held their charge for decades.

Other than that - I'd plan on changing every component part to R-134a spec.'s. Vintage Air - might be able to supply a 134a evaporator core - that would fit inside your existing housing...

FWIW,

Carl B.

[ZCurves]

Kai,

I think you are spot on to look for a systemic approach to a retrofit. You stated that the present system was non-functioning when you bought the car, throwing parts and freon into the car is just going waste your time and money. If you want a long-term solution, that is going to work - you have to change all of the components. Since the car is all apart, now is the time to do it right. I replaced everything when I was restoring my Z and what I went through may help.

First you need a shopping list. Some of the parts are going to be a challenge to find - especially the Evaporator. You will need an aftermarket evaporator with the standard flared fittings. In-fact everything that you will be buying should have the flared fittings. The stock evaporators were aluminum and featured a good -but proprietary expansion valve. The existing Condenser and Evaporator are going to be loaded with 30+ year old Mineral Oil that has varnished and become contaminated - THIS is why you replace them. Any PAG oil that mixes with Mineral Oil will gel, I have done it on the bench and seen it with my own eyes. Besides this unholy mixture certainly will have poor effects and cooling performance when subjected to extreme heat and pressure as the AC is functioning.

Here is a list to get you started:

• Evaporator
  
• Expansion valve or consider having a custom line made to handle a Orifice Tube. Replaces copper High Pressure line in the dash....
  
• Condenser
  
• Pressure switch
  
• Dryer/Receiver
  
• Rebuilt stock compressor or one from any Nissan/Datsun vehicle with a L-28 motor. However the fitting configuration WILL be different.
  
• 9oz. PAG oil (50% in a clean, rebuilt compressor. Save the other 50% for first time charge via low pressure side).
  
• 12 volt 'Pusher' fan for Condenser - R134 has higher head pressure and with 110 deg. in Tucson, you need as much air as possible flowing over the Condenser.
  

You will need to have the Low Pressure and High Pressure rubber hoses refitted with new R134 hose (not cause they might leak, but because they're Old!). There are AC shops around that will make up hoses for you for ~$100 using your original fittings. You must first mark the 'clocking' or position of the fittings so they will match back up to the compressor. **Having new AC hose made up is where you could change compressors from different models and use the new hose to 'adapt' back to the car.

Two other changes that you should absolutely consider are:

1.) Taking opportunity to do some R&R on the AC Plenum when replacing the Evaporator.

2.) Changing the Heater Core. There is no better time than NOW to change the heater core.

As you get into this project there will be other little areas that we can discuss in greater detail. Just PM me or post back to this Thread.

Edited June 4, 2012 by ZCurves

[Threehz]

Wade,

I know that refilling an R-12 system with r134a will work, but it is not a proper solution. The main problems being you will have greatly reduced efficiency, and eventually the system will fail prematurely (from everything I've read).

Carl,

You mentioned that r134a is just as efficient as R-12 in a proper system, that is my entire reason for this thread. Many people believe r134a is not as efficient as R-12. This is mostly due to improper conversions. I'll definitely look into more info on those conversion kits you mentioned. I also totally agree, part of my write-up when I figure this conversion out will include of course replacing all o-rings and hoses (if needed) to bring the system up to working order.

ZCurves,

You know exactly what I'm talking about, thank you for all the great information! I'll get in touch with you soon about some specifics concerning parts. As for the PAG oil going 50% in the compressor, I found that a great way to do it is by putting a little bit of oil in each component (2oz in condenser, 2oz in evaporator, etc, and the rest in compressor). Thanks for the tip about the heater core, but I literally just took the old one out, and I'm R&R'ing it's other components before I put the new one in.

Right now I mainly am looking for item specific input. If anyone knows any r134a components that work in our Z's, please share! That will be the only real hard part. (I'll be researching it as well)

Thanks guys!

[Wade Nelson]

The problem with the "systemic" approach is you'll end up with an AC system worth more than the price of a used Z. And one screw-up and you've just munched or contaminated expensive new components.

I suggest the "get it working" and improve it "one piece at a time" approach. A couple of cans of R134 and you can see if your compressor works. Find your leaks. You can replace hoses piecemeal. Save the new dryer receiver till you install the last new part.

If you've got debris, metal or otherwise floating around your system, let it destroy your OLD compressor or clog your OLD expansion valve, not a nice new one.

This whole business about "molecule size" is a straw man. Sure, in 2 years, all the R134 may have bled out of a R12 system. But you're more likely to deal with gross leaks, compressor seals, pinholes in your condensor, etc.

If "molecule size" were your only problem two more cans of R134 every 2 years would solve it, and that's a LOT cheaper than replacing every component in the system.

If the system is working well, and isn't contaminated with air or water, you'll never notice the 15-20% loss of efficiency from using R-134 vs R12.

But hey, maybe you've got lots of money you want to throw at it. I'm just suggesting "do it all at once" approach may be far more expensive than toe-dipping.

Edited June 4, 2012 by Wade Nelson

[Walter Moore]

Ahem: "...never notice the 15-20% loss of efficency..." You do understand that he is in New Mexico, right?

Since you already have the dash removed, this would be a great time to do this work. You can pick up a complete kit for around $1200, which is a lot less than the value of the car once you have it working.

Personally I removed the dealer installed York compressor and air conditioning from my 71. (York peppermint patties are OK, but the compressors never worked.) But then around here we call 90 degrees F "Hot". I cannot image driving an un-airconditioned car when it is 110 F.

[SteveJ]

But then around here we call 90 degrees F "Hot". I cannot image driving an un-airconditioned car when it is 110 F.

When the humidity is low and the air is flowing through the car, 100+ isn't too bad. I drove my 73 many times in Northern California in those conditions. As long as you're moving, it was fine.

[Wade Nelson]

Tell me more about "complete kits" for only $1200.

[Threehz]

r134a full kit, 941$ new

http://www.zcarsource.com/air-conditioning-kit-74-78-r-134-new_8_52904_197295.html

R-12 full kit, 650$ new

http://www.zcarsource.com/air-conditioning-kit-74-78-new_8_52904_66286.html

But both of those are WAY too overpriced...

I don't know why you guys are seeing this as such an expensive upgrade? If it was going to cost between 500-1000$ I wouldn't do it right now. For my 1991 BMW 3-series, it was less than 300$ for a full conversion to r134a, and that's with brand new OEM BMW parts. (Including condenser, dryer-receiver, evaporator, expansion valve, pressure switch, around 64 o-rings, and the PAG oil)

Wade,

You did make me think of something important. You said, "If you've got debris, metal or otherwise floating around your system, let it destroy your OLD compressor or clog your OLD expansion valve, not a nice new one." Flushing any re-used components (evaporator & compressor are the only ones that can be re-used, and evap should be replaced) is necessary. There are special R-12 flushing compounds, however when used properly, mineral spirits will work perfectly. This is just as important as having a vacuum pulled and having the r134a charge done professionally or by someone with the correct tools (Wade in the original article you linked, you explained this pretty thoroughly as well).

Now the kit above from ZCarSource is great, but the compressor is a big reason why it's so overpriced. I believe some self R&R on an original compressor will make just as good (seeing as that's what it appears they did). That kit is also missing an auxiliary fan mounted in-front of the condenser (as ZCurves mentioned). These can be found pretty cheap new online in a range of CFMs, not to mention junkyards offer a great solution as well.

Thanks for all the great feedback guys, I really would like to make it easier in the future for others to do AC conversions/installs, and my Z happens to be in the perfect state to use as a guinea pig. I'll try and source some of these parts soon (I've been totally bogged down with work and life recently)

[Wade Nelson]

FWIW, I asked Glen Farrell, "Mister Air Conditioning" down in Cajun country what the absolute best solvent was to flush an older AC system with. He said "Nice fresh R12 or R134".

You could hear the screaming from the EPA all the way from Washington, but there it is.

[ZCurves]

I looked back at some older posts, and collected the various Parts Suppliers/ Part Numbers/ $$$ and put it all here. Feel free to update for future readers...

Great place with LOTS of AC parts (including Heater Control Valves!)...

AMC (Air Manufacturing Corp.)

1040 E. 4TH STREET

GRAHAM, TEXAS 76450

(940) 549-0288

www.amcmfg.com -Or-

http://www.marketworks.com/storefrontprofiles/default.aspx?sfid=75198

Condenser:

http://www.autopartswarehouse.com/details/QQNissanQQ280ZQQSillaQQA-fs-C_CondenserQQ19751978QQSILLAC8060.html

Accumulator/Drier:

http://www.discountacparts.com/addtocart~year~1978~make~Nissan~model~280Z~descript~A-C_Accumulator-Drier~part~60-30571.asp#

Part # 60-30571 $40.00

Remember, Nissan used a lot of the same AC components on ALL of their cars (and still do!). So, if you have to, look for model years for 810's, Maximas, Stanzas, etc.

Evaporator:

http://www.rwiamerica.com

~or~

http://www.thezstore.com/page/TZS/PROD/16-7520

Expansion Valve & Accum/Drier: (USE FLARED FITTINGS!!):

http://www.onlineaccompressors.com

Part Number: 60-40201

Heater Valve Repair Kit from NAPA:

Part No. BK 6601000

or buy new from: www.amcmfg.com

Pressure Switch:

http://www.drivewire.com/vehicle/nissan-280z/ac-switch/

Four Seasons Part # FS35758 $5.70

Here is a link to an old post where we discussed this topic before....

http://www.classiczcars.com/forums/showthread.php?t=39425&p=375096&viewfull=1#post375096

Parts Bottom Line... Look around, internet search, Use this forum! You WILL find the parts needed -often at a reasonable price. After all - it's not Rocket Science, but it is science...