My car has the dealership installed VPC AC. I purchased the car 5 months ago and the AC doesn’t blow cold. I have no history on it. Still had a little pressure in the system. I’m thinking of charging it with R134. Has anyone done this and know how if it will work and how much I should try to put in the system?

The VPC ac system used R-12. Charging it with R-134a will ruin the system. They are NOT compatible.

The York compressor won't work with R-134a. You will have to use a rotary compressor to use R-134a.

You also need to change out all the hoses for barrier hose, and replace the expansion valve. You will get AC that works, but is not ice cold. To get ice cold, you have to add an additional condenser. I used a 911SC condenser mounted under the engine lid in place of the rain tray. Put two 12" fans on it, and you are good to go.

The AC in Betty's 914 blows ice cold on a 100 degree Texas summer day... like today.

Good list Clay as usual, you will also need to replace the dryer. As far as the amount it will be almost an entire system at that point so oil, and Freon. And then done buy pressure.

Here is the entire setup if you don't feel like screwing around with DIY hose making and sourcing parts.

If you are just trying to get the system working again without replacing the compressor you may be able to use an R-12 replacement freon. I think there are a few of them available. You may have to evacuate all of the R-12 out of the system first and I would replace the dryer as well. One of the available replacements is "Freeze 12"

It's more work but replacing the compressor with a modern Sanden is worth it.

The r12 oil + r134 = gel... so no good. You will need to flush out all the old oil from the whole system then use the hybrid swap over oil. New dryer but it's a generic size so that's easy. The rest of the hard parts will work fine.

The fittings will be r12 so you will have to buy a set of ac gauges and do it yourself or buy the adapter fittings to get a shop to do it.

Refill is done best by pressures. You will also need to apply vacuum to the system before fill to remove the air and moisture to get the best result.

Having a local hose place make new hoses will be a couple bills, but they'll last decades. I don't know if old hose will play nicely with r134 and the oil.

R134 molecules are smaller than R12 molecules and they leak out through the old hoses, even if the old hoses were new the R134 would leak out through them. This is why you need new barrier hoses.

R134 is also not as thermally efficient as R12, so a R134 system has to be bigger to provide the same cooling capacity as a R12 system. This is why an additional condensor or a larger condensor is needed. The rotary compressor also moves more freon with less load on the engine than the York piston compressor.

R12 systems are expensive to upgrade but they are also expensive to maintain. R12 is probably $50 a pound and the system has to be serviced by a licensed tech (at least in CA).

Jim

They can be too large. also. My power plant is out of a Huge Subaru station wagon that had dual sunroofs. I keep it set at the lowest setting possible. If not, I need to wear a winter coat if I use the AC.

Likely smarter AC people here but as the chemist, these replacements are most often flammable hydrocarbon mixtures. They work but add additional concerns in cases of accidents and leaks. I tend to be simple and grade things on the good bad scale.

Flammable gas under high pressure = bad in my book.

I redid my AC system back in 2013. Still blowing ice cold.

As others have noted, simply pumping in refrigerant will likely be a fail. Even if it works briefly, the old hoses, seals, connectors, etc. will likely leak. Additionally, You can not put R134 into and R12 system without flushing out all the old oil from every part of the system (which you should probably do anyway). You will definitely need a new receiver-drier at the VERY minimum.

The first step in testing for leaks should not be to put freon in but rather to take air out. Vacuum down the system via manifold gauges. Let it sit overnight. If you lose vacuum then the system has a leak.


I went with a Sanden style compressor but kept everything R12 (I stocked up years ago and yes, I am licenced). Original condensor, evaporator, fan and it blows ice cold. The Sanden style compressors rob a LOT fewer horsepower that the heavy York boat anchors (approx 2HP vs approx 12HP)


1. The Seltec compressor is model 103-55021. It fits but snugly. Might have been easier with next size down.

2. For me, the proper belt turned out to be a Dayco 15460 from Advance Auto Parts. As noted, you do not get a lot of room to adjust belt tension. Make sure you have the pulley behind the fan lined up right or you will need to do it over again (as I learned).

3. This job would be a pain without a lift. If the engine were out it should also be easier. Would not want to tackle this job on my back.

4. I replaced hose and fittings with Aeroquip EZ-Clip components. The hose is more flexible than barrier hose and the clip system is easier than crimping. Size 8 hose on the high pressure side, size 10 for low side, a small piece of #6 from condensor to receiver drier. Finding R12 Aeroquip fittings was a challenge.

5. I stuck with R12. You need to drain approx 4 oz of oil from compressor and replace with mineral oil (available at Napa). If you flush out the evaporator and condenser, add an ounce per component. (You need to remove them to properly flush). I flushed everything vacuumed to remove moisture, purged with nitrogen to remove moisture, vacuumed again. Moisture is the enemy of AC systems.

Finally, autoacforum.com is where all the AC junkies hang out. Tons of good info there.

We only put r12 in the original 914 ac systems, DPD OR VPC with the York compressor

Not true. I've done countless pre-93 ac repairs with r134. If the Nissan factory didn't change hard parts for the new refrigerant then it wasn't needed. Not even the compressor changed.
I still get a respectable 40F temp drop, tuned via pressure not volume.

The condenser location/position/fan is definitely the weak spot on 914s, and the York compressor. The engine swapped 914s with modern compressors and condensers in the air stream in front of the radiator don't have any cooling issues.

The aftermarket evaporators are way oversized for out little 2 seaters.

FYI the compressor is the same for all of them. Nissan used the same system in my Pathfinder SUV and 2 seater Hardbody... one of them gets nippy really fast. Same as Chevy did with Dads C10 and the Suburban except that one will keep meat frozen.

http://redtek.com/English/product.asp?ID=18

I would and do run RedTek in all my older cars. It is a hydrocarbon mixture however it has the same autoignition temperature as R134a so i don't know if you can call it any more flammable. As an added bonus when R134a does burn it produces a toxic gas where as RedTek doesn't.

As with most things there seems to be a campaign to tout all the horrors of using an un-patentable product but if you look at the actual reality of it there are a LOT of advantages to running a hydrocarbon blend, especially in an older car.

RedTek should be a drop in replacement on a 914 where as i wouldn't run R134a without replacing pretty much every component of the system. I speak from experience as I attempted to do this on my Vanagon which has a similar AC system (long rubber hoses running front to rear) and was treated to an exploded high pressure hose in the first 30 minutes due to inadequate condenser capacity for R134a and the fact that early Vanagons have no high pressure switch. Did some research, replaced the hose, installed RedTek and its been cooling well ever since.

Redtek has a much larger molecule size so it wont penetrate older non barrier hoses, runs at much lower head pressures so things don't blow up and you are not forced to install an upgraded condenser to keep the pressure in check. Its compatible with both mineral and PAG oils so no need to flush the oil. No more flammable than R134A and if it does burn it isnt toxic like R134a plus you only charge with about 1/3 the volume of R12 or r134a so there isnt as much in there to burn anyways. The chemical itself is much less harmful for the environment than both R12 and R134a. takes less energy to use and cools better.

I probably sound like a crazy salesman here, but after going through the headaches of getting the AC working in my 85 vanagon Westfalia (which was complicated by attempting to use R134a first) discovering RedTek and then resurrecting two other older Porsche AC systems with it with zero issues, im pretty passionate about it. My favorite experience was with a 80'924 turbo i picked up that had sat non op for 20 years before i got it. After I got the car running I did nothing but vacuum down the AC system, charge with a can of RedTek and it started blowing cold immediately. Didn't even change the drier or a single seal.

It is the easy button for older AC systems.

Very popular with the Vanagon crowd
https://www.thesamba.com/vw/forum/viewtopic.php?t=292488

Well in reality it does not matter what your using you will need to do the follow.

Replace the dryer
Assemble the system:
Draw vacuum and make sure it holds for a period of time, that period is up to you.
If it leaks fix the leak
Rinse and repeat until it can hold vacuum longer than you can hold your breath.
Install system in car
Draw vacuum again, and test system, you may have to loop back. This did add a few steps but makes it a lot easier to fix issues and find leaks when you can flip things in 3D
Add the oil associated with your choice of Freon in the approbate amount for your system
Start the car
Fill the system to the approbate pressure for the ambient temperature
Check the system for proper functionality

Drive with out your back and undercarriage getting all swampy.

Now the highly recommended option.
New Rotary Compressor - why less load on the engine than the engine driving another piston engine. More efficient operation, and if you wanted to make the system better you use one of the more Modren units that is constantly on, and varies refrigerant flow based on need. Makes the system even more efficient. Or switch over to an electric compressor system, these can be $$$$ and I have not seen a good DIY on the controls of these yet.

The controls are not the problem. All of the electric compressors draw way too many amps to work with a 76 amp 914-4 alternator. I am going to run one in my car, because of the 964 alternator. It is 190 amp to run all the electrical accessories on a 964. The compressor I am looking at draws 32 amps. With the factory alternator, I am positive you are going to have dead batteries continuously. Years ago, I ran an electric heater in my 914 (this was before the six conversion). That heater only draws 25 amps, and I had to plug the car into a battery charger every night or it wouldn't start the next morning.

The nice part about the electric AC compressor will be the ability to turn it on to cool down the car without the engine running. 20 minutes of running shouldn't prevent the car from starting. And that is something valuable in a state where the best parking space is not the one closest to the door, but the one with the most shade.

Another good part about the electric compressor is that you aren't limited to mounting it somewhere in line with the front pulley on the engine. So it may not be necessary to chop up the engine tin and engine shelf, degrading the performance of the engine cooling system.

--DD

Thanks Clay, just solved two of my problems, now I don't have to run as much A/C line, all of it will be in the Frunt. A bit larger electrical wire, but the is easier to route than barrier hose.

BTW Clay you have the P/N for that 964 Alternator everything I have found says 115 Amp.

The 964 alternator won't fit into anything but a 964 engine. You can't put it in a 914-4 at all.

I was hoping I could sneak it into the fan shroud of a 914-6

Sorry...it won't fit. It is about twice as long as an early 911 alternator. And the fan won't bolt up either. You would have to use the whole 964 alternator, fan, and shroud. Plus the kit to lock the fan and alternator together.

This seems like a good solution for a high amp alternator instlled on an earier 911 engine.

I feel like a now, sorry for the hijacking.

Just for education purposes...

Here are some pictures of a factory 914-6 alternator and fan compared with a 964 alternator and fan.

Click to view attachment

Click to view attachment

Click to view attachment

As you can see, the factory 914-6 alternator/fan assembly is smaller in diameter. The last picture really shows off the size difference. The little fan on the back of the 964 alternator is there just to keep it cool.

I actually tried to fit the 964 alternator in the 914-6 fan opening. Its too big.


Your aftermarket alternator looks like a great solution for early cars with electric AC compressors. I suggest you get the serpentine belt kit from Clewett engineering if you use that alternator. Besides the ability to handle more load, it makes the belt easier to change too.

Yes I think it would be a great option for electric A/C. The 964 can fit, but it has to be milled down to do it. A thread on Pelican shows the results.

And yes Serpentine belt would be the correct choice