1984 720 A/C Expansion Valve Replacement

[bluexl]

Has anyone on here changed out the AC Expansion valve on their 1984 720 truck? Mine is an 84' Nissan 720 Sunrader (Mini RV). I have the Haynes Repair Manual, but they do not suggest a home mechanic work on the A/C due to the refrigerents, so it is not of great help. My system is already free of refrigerent as the compressor and compressor hoses were missing.

 

I installed new metal lines out of a pathfinder that run across the rear along the firewall, and I built new compressor hoses using the ends of an 86 truck to mate them to a new 86' compressor.  I have a new condensor and drier as well.

 

The only piece that I am not sure how to change at this point is the expansion valve. Any help would be greatly appreciated.

 

Thanks!

 

 

[datzenmike]

That a Z24i engine????

[bluexl]

11 minutes ago, datzenmike said:

That a Z24i engine????

No it is a Z24. The air cleaner must have been swapped at some point with a z24i. 

[Charlie69]

Being an 84 it should be carbed.

[bluexl]

14 minutes ago, Charlie69 said:

Being an 84 it should be carbed.

Yes it is carbed.

Edited August 17, 2021 by bluexl
Clarification.

[datzenmike]

 

Says right on it Electro Injection. lol someone swapped a Z24i air filter on.

[NC85ST]

I have on my ‘85 ST. It’s somewhat of a pain. It’s under the dash attached to the evaporator, which is inside a two piece plastic box, held together by several spring clips. The ones on the back side, of course, are the hardest to get to, especially when you go to put everything back together. Once you get the box opened up, it’s easy to replace. You can take a utility knife or razor blade to cut open a tar-like substance that the expansion valve probe is covered with. I think that there is a clip holding the probe to the a/c line also. It’s been a while since I did this. Hope this helps.

[Charlie69]

Here scroll down to find the correct year.  The expansion valve on a factory AC is metric threads some of the dealer installed ACs have SAE threads.  Pictures of your setup will help me tell if factory or dealer installed.  I have owned both over the years.

 

https://www.partsgeek.com/mmparts/ac_expansion_valve/nissan/720.html

 

 

[bluexl]

4 hours ago, NC85ST said:

I have on my ‘85 ST. It’s somewhat of a pain. It’s under the dash attached to the evaporator, which is inside a two piece plastic box, held together by several spring clips. The ones on the back side, of course, are the hardest to get to, especially when you go to put everything back together. Once you get the box opened up, it’s easy to replace. You can take a utility knife or razor blade to cut open a tar-like substance that the expansion valve probe is covered with. I think that there is a clip holding the probe to the a/c line also. It’s been a while since I did this. Hope this helps.

This is helpful, thank you. Is it the box under the dash that is closet to blower motor, or is it the box right behind the console/shifter?

 

Thanks again.

[bluexl]

43 minutes ago, Charlie69 said:

Here scroll down to find the correct year.  The expansion valve on a factory AC is metric threads some of the dealer installed ACs have SAE threads.  Pictures of your setup will help me tell if factory or dealer installed.  I have owned both over the years.

 

https://www.partsgeek.com/mmparts/ac_expansion_valve/nissan/720.html

 

 

Thank you, I ordered the part from Parts Geek last week and have it on-hand. Just need to do the install. Parts geek is also where I got the nes compressor and dryer. Thanks for sharing 

[powderfinger]

It's the box to the left of the blower motor. Since you are trying to get the AC working it's probably a good idea to take that all apart anyway because there is no telling what's in there. Trucks this old tend to have gotten leaves, trash, mouse nests, etc in there over the years. Clean it out real good and use something to clean the evaporator off as well before reassembly.

[NC85ST]

I hope this helps. I would like to know more about what you did under the hood. Using Pathfinder lines and an ‘86 compressor? Any modifications to attach to the evaporator? Use the ‘84 a/c mount, for the compressor, on the engine? Also where is the dryer mounted?

[powderfinger]

22 minutes ago, NC85ST said:

I would like to know more about what you did under the hood. Using Pathfinder lines and an ‘86 compressor? Any modifications to attach to the evaporator? Use the ‘84 a/c mount, for the compressor, on the engine? Also where is the dryer mounted?

 

 

same here

Edited August 18, 2021 by powderfinger

[bluexl]

@powderfinger and @NC85ST. I will post images of what I did both for the 84 720 Sunrader and for the 85 720 4x4 when I am done. I am working on the A/C for both, so they are set up similarly. For now the Sunrader is ahead in line so I will finish that one first. Hopefully.

 

The low pressure hose ends that meet the evaporator in the 84' and 85' are different from each other in that one is female and the other is male, so the 86 setup did not work on the 84 Sunrader. It could be specific to the RV, I don't know. (See image 1)

 

In the 84' Sunrader I  amd using the pathfinder low pressure hose. However the end that mates to the compressor will need to be swapped out to that of an 86 D21. I used the original High Pressure hose, but swaped out the end that mates to the compressor to fit the newer style compressor. The 84/85 Hoses will not mate to the 86 and newer compressor.

 

In the 85' 720 4x4 I use a complete 1986 D21 low pressure hose setup that comes from the evaporator to the compressor. The end on the low pressure hose where it bolts to the compressor is bent upwards about 20 degrees to avoid the steering box(same for the Sunrader). I used a heat shield on the high pressure hose where it almost touches the manifold (image 2).  The high pressure discharge hose and valve were used (image 3), but with a modified end that includes metric beadloc female O Ring 45 Degree M20 x1.5 mm Nut to hsoe adapter. (See image 4).

 

The dryer and condenser are new OEM styled pieces. Nothing was changed on them other tha R134 fittings.

 

Image 2.

 

Image 3.

 

 

Image 4.

 

[bluexl]

On 8/18/2021 at 8:05 AM, NC85ST said:

I hope this helps. I would like to know more about what you did under the hood. Using Pathfinder lines and an ‘86 compressor? Any modifications to attach to the evaporator? Use the ‘84 a/c mount, for the compressor, on the engine? Also where is the dryer mounted?

Thank you for sharing this.

[Charlie69]

From the picture of the 84 it might be a dealer installed unit.  I say tis because of the steel nut all the factory AC I have worked on are like the 85 picture including 1980 720 up.  2wd and 4wd are the same except hose routing.  85/86 had different compressors from earlier models..

[bluexl]

On 8/19/2021 at 9:28 PM, Charlie69 said:

From the picture of the 84 it might be a dealer installed unit.  I say tis because of the steel nut all the factory AC I have worked on are like the 85 picture including 1980 720 up.  2wd and 4wd are the same except hose routing.  85/86 had different compressors from earlier models..

I think you are right because, am I crazy or is the expansion valve inside the engine compartment (see item 1. in image 1.)where the high pressure line meets the evaporator port? o I might not have to get into the interion box to change the valve after all, atleast not on the 84'.

 

Image 1.

 

 

[Charlie69]

Yes sir that is an aftermarket non nissan AC.  I had one in one of the 1980 720 I had years ago.  It worked great.

 

If you have an automotive AC place in your town take the expasion valve to them to see if they can match it.

[NC85ST]

Just curious, in what way are the hose ends different, that go to the compressor?

On 8/19/2021 at 9:13 PM, bluexl said:

modified end that includes metric beadloc female O Ring 45 Degree M20 x1.5 mm Nut to hsoe adapter. (See image 4)

And I’m unfamiliar with what this is and how it works. 
The a/c system on my 85 is sealed up good, but the compressor squeals like crazy above idle. I’m thinking that going with newer parts might be a good idea in the long run. That’s why I’m so interested in this.

[bluexl]

On 8/22/2021 at 12:18 PM, NC85ST said:

Just curious, in what way are the hose ends different, that go to the compressor?

And I’m unfamiliar with what this is and how it works. 
The a/c system on my 85 is sealed up good, but the compressor squeals like crazy above idle. I’m thinking that going with newer parts might be a good idea in the long run. That’s why I’m so interested in this.

 

If you have your old high pressure hose you would change the mount that mates to the compressor (see image 1 for differences). That is the only change you will need to make to this hose. I changed both ends on mine and kept the newer charging port because I did not have the old hose to begin with. The older hose mount holes do line up f you wanted to give it a try, but I was worried that there would be a leak, so I went with the matching end. You would keep the same mount that mates to the condenser if you have your older hose. If you wanted to keep the newer style hose with the charging ports, that is the only reason to use the modified end that includes the metric beadloc female O Ring 45 Degree M20 x1.5 mm nut to hose adapter. Since your existing system has the port over by the dryer, you don't really need it, so you just convert that port to the newer style using a R134 conversion kit.

 

Image 1. L: 84'/85' style high pressure hose to compressor mount. R: Newer style high pressure hose to compressor mount.

 

 

 

Low Pressure Hose

The low pressure hose from the end that attaches to the evaporator at the passenger side firewall to the end that attaches to the compressor will be used from a 86 to 96 D21 donor truck. You can also use the compressor from these same trucks as the mounting bolts are the same, though I purchased a new one for just over $200, at partsgeek, part no. Four Seasons:8242-05040532.

 

You cannot attach the 84/85 low pressure hose to the newer compressor as the bolt holes do not line up (see image 2). I used a pipe bender to bend the newer style hose pipe a few degrees upwards to avoid the steering box. It was simple.

 

Image 2. L: Newer low pressure hose to compressor mount. R: 84'/85' older style low pressure hose to compressor mount.

 

 

Make sure to take a couple of mounting brackets like the one in image 3, as well as several mounting screws that are shown in image 4 (I just took some extras from the truck at the wrecking yard).

 

Image 3.

 

 

Image 4.

 

 

Everything should bolt on without issue, once you make the bend to avoid the steering box. The only other thing I did is referenced in my earlier post, and that is to add a heat shield where the high pressure hose is a bit close to the manifold.

 

Hope this helps you.

 

 

 

 

Edited August 24, 2021 by bluexl
typos