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Drier recommendations


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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.

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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.

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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.

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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 ?

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Posted (edited)
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 by cgsheen1
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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 ....

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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.

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Posted (edited)

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 by EuroDat
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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.

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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

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Posted (edited)

To clarify what I have done, I have or had a working converted to R134a system but had a very slow leak requiring me to recharge the system every year or so.  I have just rebuilt and installed a fresh motor and as part of that, I purchased a new Sanden 508 compressor to replace the factory unit. (the source of my leak)  With the new compressor installed, I have to replace the 2 flex lines that connect to the compressor which has the high / low ports in a different location requiring about 5" longer lines and connections with modern o-ring fittings.  Nissan used most all #8 flange fittings in the factory system.   Currently waiting on delivery of the parts to build and crimp the new flex hoses, then... I can re-charge the system.  If I remember right, I think I used close to 2+ 12oz cans to charge the evacuated system. 

Looking back, the drier was the easiest part of my upgrade, the copper hardlines connected easily, and fits perfectly in the stock bracket.

Edited by S30Driver
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As mentioned above I would like to keep the engine bay stock looking . I would like to keep the hard lines going to the compressor which would entail using a drier with compression fittings. I will be upgrading to a new condenser that will have o ring fittings. Hooking up the condenser to the drier would require going from an o ring (on the condenser) to a compression fitting on the drier which would be easy if I were to put a hose in the process of connecting the two. If I try to run a hard line between these two then the only way I see that this can be done is to use an o ring to compression adapter. Has anyone ever used one of these adapters? I have never had the need to make a connection like this on the cars that I have worked on and therefor have never used an adapter like this. Adapters are available from Nostalgic AC.  Nostalgic AC - Flare Adapters - Fittings & Hose Kits

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Posted (edited)

You need to find out the fitting size on your new condenser.  #10  or  #8.  The flare fitting on the drier is #8.

I am waiting for the adapter from Nostalgic Air to convert from the evap hard line #8 flare to #10 hose for the compressor suction port.

You cannot use hard lines directly to the compressor ports since it is bolted to the motor block and can move.  That is why Nissan used 1 foot flex lines which I need to extend 4 or 5 inches with o-ring fittings and service ports due to the new and different compressor.

Edited by S30Driver
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I am aware of using a flex line between the compressor and condenser. My question relates to the hard line from the condenser to the drier.

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On 7/11/2021 at 1:07 PM, Dave WM said:

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

Hi Dave, Just went through my notes and you are correct. I found a formula: R12 charge x 0.9 - 0.12kg = R134a charge. It is an approximate calculation and generally results in 70 to 85% of the original charge.

Ex. 1.2kg R12 x 0.9 = 1.08 - 0.12 = 0.96kg R134a (80%)

Like I said, NO expert here......

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The original hard lines use standard flare fittings for refrigeration tubing. (Journeyman Plumber (besides novice HVAC tech) - we used flare connections on soft copper water or air tubing as well...)

HVAC Flare fittings aren't the same as AN fittings - they use a different bevel - you can't mix them.

The liquid line in an early Z is just stock 3/8" soft copper refrigeration tubing - can be bent with a 3/8" tubing bender of you choice, can be cut and re-flared with an HVAC flaring tool, can be brazed. I don't think the stock copper can be made an o-ring connection but I don't know for sure... I do believe there must be a way to transition (if an o-ring fitting can be brazed onto copper tubing, there you go...).

Euro is correct R-12 volume vs. R134a - I go off pressures, not exact refrigerant weight, but the conversion above will get you in the ballpark.

(As a plumber I have a fondness for flare fittings and a subsequent ambivalence for o-ring fittings. (I said "ambivalence" but I really meant "dislike"...) I find the flares to be much more trouble free when done correctly. And since I have all that $^!# from my plumbing career, I can easily make or repair flare connections which, I guess, some people struggle with.)

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S30, the condenser that I am using (new from Vintage Air, 12" x 24") has #6 and #8 0 ring fittings. I will try to run a hard line from the #6 condenser fitting to the drier. The drier I have has #6 male flare fittings so the exit side of the drier will mount up to the stock hard lines going to the evaporator. I am going to use one of NostalgicAC's flare to o ring adapters. I will probably have to replace the stock Datsun #6 hard line that goes from the condenser to the drier with a hard line that has o ring fittings on both ends.

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Posted (edited)

That all makes good sense.  Replacing many of the #8 flares that Nissan used with o-ring fittings should be more resistant to any future leaks in the system, which is a very good thing.  (although cgsheen1 likes the flares which makes me happy since the only o-ring fittings in my system are on the new compressor)

Should get the last fitting I need to crimp the line to the low suction side of the compressor today.  It is a #8 flare to #10 hose straight beadlock fitting.  Then I should be able to draw down the system and recharge it.

Interestingly, I purchased the o-ring 135 degree compressor fittings with service ports from Cold Hose.  Nostalgic Air did not have them with the option of the service port either left or right side, only one side.  I wanted ease of access to the service ports with the low side clocked left and the high side right.

Edited by S30Driver
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