I need to replace my Hatachi compressor and in the process I will convert to 134a. I need to find a replacement for my drier. Does anyone have a recommendation for a replacement that has ports that are close to matching up with the existing hardlines. I read somewhere that the later Nissan AC systems used a drier that was a close fit. Does anyone have an application or part number to suggest. I know I can just get a generic drier and make it fit but I would like to keep the installation looking as stock as possible. I have a '75 280Z.

That drier is hard to come by. Somehow a local AC shop got one for me, so you could try there, perhaps they have a wholesaler that can supply. The other option if you have the old one is if you can find a rebuilder, yes they can be cut open and refurbished.

I can understand wanting it to be as OE as possible but, in this case I don't think its worth the effort, Just rebend the hard line and go for the cheap 15$ generic drier.

Try Nostalgic AC. https://nostalgicac.com/driers-valves/driers.html

Do the dryers have desiccant in them?

Anything else inside?

Here is the drier I installed, I used a cut off wheel to remove the bracket, ground the weld down, painted gloss black, fits perfect.

https://www.amazon.com/gp/product/B003R3PX0Y/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

I also put in a new switch and removed the factory paint covering the sight glass ... lol

https://www.amazon.com/gp/product/B000C2M9NM/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

I am just completing the refresh of my ac system with its new Sanden 508 compressor, waiting on parts for the new flex line which need to be slightly longer with o-ring ends for the compressor.  Got most of the hose parts from Nostalgic Air.

S30Driver, thanks for the links to drier and pressure switch. I have seen this drier on a Utube video. Question: on the second link (for the pressure switch) shouldn't the pressure switch be a high pressure switch not a low pressure switch as what was originally installed ?

22 hours ago, Patcon said:

Do the dryers have desiccant in them?

Anything else inside?

They have a filter and desiccant and are generally designed to trap stuff you want to keep away from the expansion valve and the compressor. In the stock system, there's also a fine screen in the liquid line fitting at the bulkhead - just ahead of the expansion valve - as a second line of defense.

And YUP "Cruzzar", the early A/C systems only had a high pressure switch. Low pressure switches didn't come until the ZX's. The FSM does create some confusion by calling it merely a "Pressure Switch" (without specifying if the switch is "cut" on overly high pressure OR at low pressure).

Edited July 10, 20213 yr by cgsheen1

7 hours ago, Cruzzar said:

S30Driver, thanks for the links to drier and pressure switch. I have seen this drier on a Utube video. Question: on the second link (for the pressure switch) shouldn't the pressure switch be a high pressure switch not a low pressure switch as what was originally installed ?

You may be right.  The switch is another difficult to source part in a high pressure version.  I looked and could not find one.  My oem switch had a broken contact tang so I had to replace it.  If your original switch is good, maybe you can transfer it to the new drier.

Maybe someone with more AC expertise will chime in here.   @Captain Obvious what say you ....

Thanks for the vote of confidence, but I'm not an A/C guy. 

I don't even know enough to be dangerous. 

I looked in the AC section of the 74 FSM. It says that the switch is a high pressure switch. I wouldn't be surprised if Amazon doesn't have a high pressure switch (or high/low pressure switch) somewhere that has the same threads as the switch Jim used.

I'm a bit like the Captain. Any advice I would give wouldn't end well. I want to restore my AC and interested in what you guys (Cruzzar and S30Driver) do to restore yours.

I didn't know they changed from a high pressure to a low pressure switch. Low pressure must have caused more problems than high pressure, so they change somewhere in the 280ZX model.

What I have learned in my research and meager training in an oil refinery job 25 years ago, but that was R22 and ethane compressors in a hydrocarbon extraction plant making ultapure hydrogen to gas chromatographs.

R12 has a lower condensing pressure than R134a and therefore requires a smaller condensor. Most (larger) american cars have fairly large condensors so generally not an issue, but european and japanese cars can have problems converting the gas to liquid in the smaller condensor and greatly reduce the efficiency of the AC.

Tha R134a molecule is smaller than that of R12, so a system that didn't leak with R12 could start leaking with R134a due to the smaller molecule and higher discharge pressures.

R12 uses mineral oil which is not compatable with R134a. The system must be thoroughly flushed before using R134a. The system can than use polyalkyle glycol (PAG) oil. Their is also a polyol ester (POE) oil.

The dryer must be replaced and should be replaced every time you open the system. It is improtant to remove all traces of water. R12 would tolerate small amount and eventually move it around to the dryer, but R134a systems the PAG oil is hygroscopic and R134a than converts it to hyrofluoric acid which will damage the hoses, compressor etc. Not sure if there are differences in the original dryers and the ones you can buy now.

A R134a charge is about 75% more than the R12 charge in the same system.

My plan based on my meager research was to remove the system flush all the components, rebuild the Hitachi compressor (found a revision kit on www.marktplaats.nl here in NL), replace the hoses, reassemble and pressure test with air for a month or so. Than install a new dryer and recharge the system. I am hesitant to go ahead and that is why I'm interested in the approach others take to get there systems operating again.

Edited July 11, 20213 yr by EuroDat

56 minutes ago, EuroDat said:

A R134a charge is about 75% more than the R12 charge in the same system.

 

I think its 75% OF the R12 charge in the same system. Not "more". May want to double check this.

I would pressure check with dry nitrogen not air. Air will introduce moisture. The nitrogen will help purge the system. Charge with niteogen. Then after testing, vacuum it down and charge with refrigerant