Micro-Tube Parallel Flow Condenser

[Dissent]

Nice job, those are pretty good temps given the ambient and idle speed, looks like it was a great success! How does it do around town and on the highway? What's your opinion of the ability to cool the rear, even without the ductwork?

 

[Dissent]

Charged with 2.8 lbs of refrigerant. No oil added. Only whats inside the new oem denso compressor. Here are my vent temps at around 3pm. Ambient temp is around 103-105.

View attachment 1785007

View attachment 1785008

@flintknapper may want to verify but I'd think you'd need a bit more oil for the 2nd evap, larger condenser and extended lines.

 

[flintknapper]

@flintknapper may want to verify but I'd think you'd need a bit more oil for the 2nd evap, larger condenser and extended lines.

Without going back and reading through all 24 pages....I think I remember guessing/suggesting that about 9 ounces would be appropriate. The Static parts (Evaps, Condenser, Drier, Lines) do not directly benefit from the oil, but a certain 'ratio' (oil to refrigerant) is desired. Also, having small amounts of oil in these components aids in oil 'return' and miscibility (under certain conditions there is oil 'drop out').

 

[ARB777]

Without going back and reading through all 24 pages....I think I remember guessing/suggesting that about 9 ounces would be appropriate. The Static parts (Evaps, Condenser, Drier, Lines) do not directly benefit from the oil, but a certain 'ratio' (oil to refrigerant) is desired. Also, having small amounts of oil in these components aids in oil 'return' and miscibility (under certain conditions there is oil 'drop out').

Can I just add oil to the system myself? Would I disrupt its current balance if I just add and not evacuate some refrigerant out?

 

[ARB777]

Without going back and reading through all 24 pages....I think I remember guessing/suggesting that about 9 ounces would be appropriate. The Static parts (Evaps, Condenser, Drier, Lines) do not directly benefit from the oil, but a certain 'ratio' (oil to refrigerant) is desired. Also, having small amounts of oil in these components aids in oil 'return' and miscibility (under certain conditions there is oil 'drop out').

Can I just add oil to the system myself? Would I disrupt its current balance if I just add and not evacuate some refrigerant out?

 

[Dissent]

I've seen oil charge cans at the store to inject only oil into the system.

 

[Mandrake]

Not bad. Here's mine at 330 pm.

 

[Mandrake]

Not bad. Here's mine at 330 pm.


View attachment 1785653

 

[flintknapper]

Can I just add oil to the system myself? Would I disrupt its current balance if I just add and not evacuate some refrigerant out?

Yes, you can always add oil (via small cans of the correct type). But....remember you can't take it back out! So we don't want to overcharge the system or your cooling will suffer for it. Your current readings are VERY good.

Being slightly undercharged (IF you are) will only result in a shorter life for your compressor and that won't occur for a long time.

If you were grossly undercharged it would be a concern.

IF you presently have a solid 8 ozs. in the system...I would be inclined to leave it alone the remainder of this summer and just monitor the performance of your system to establish baselines for next summer. You can 'tweak' it later when you have a better idea of what the unit is doing under various conditions.

IF you think you have less than 8 ozs...then adding another ounce or ounce and a half might be a good thing.

For those adding a rear A/C (a tap-in arrangement) and choose to forego adding a solenoid shut off valve (to separate the two systems) you should expect the rear unit to have a slightly parasitic effect on the front. It may or may not be an issue for you....just be aware.

 

[flintknapper]

Not bad. Here's mine at 330 pm.


View attachment 1785653

Hah....a balmy 150° F. We can make Beef Jerky inside your vehicle.

 

[ARB777]

Nice job, those are pretty good temps given the ambient and idle speed, looks like it was a great success! How does it do around town and on the highway? What's your opinion of the ability to cool the rear, even without the ductwork?

So far so good. It make

Not bad. Here's mine at 330 pm.


View attachment 1785653

I got a similar one the other day and I thought my thermometer was just not calibrated right. Lol.

 

[ARB777]

Yes, you can always add oil (via small cans of the correct type). But....remember you can't take it back out! So we don't want to overcharge the system or your cooling will suffer for it. Your current readings are VERY good.

Being slightly undercharged (IF you are) will only result in a shorter life for your compressor and that won't occur for a long time.

If you were grossly undercharged it would be a concern.

IF you presently have a solid 8 ozs. in the system...I would be inclined to leave it alone the remainder of this summer and just monitor the performance of your system to establish baselines for next summer. You can 'tweak' it later when you have a better idea of what the unit is doing under various conditions.

IF you think you have less than 8 ozs...then adding another ounce or ounce and a half might be a good thing.

For those adding a rear A/C (a tap-in arrangement) and choose to forego adding a solenoid shut off valve (to separate the two systems) you should expect the rear unit to have a slightly parasitic effect on the front. It may or may not be an issue for you....just be aware.

Yeah, since its cooling well right now i kinda dont wanna touch it for a bit unless it gives me a problem. I really wanted to add 2 oz of oil (per proair) but the shop said no need. I read somewhere here that the brand new denso compressor comes with the appropriate amount of oil for the entire system. Whether it means front only or with rear ac, i really dont know. Its the same compressor though for rear ac equipped 80s.

As for the tie in process. I agree that a solenoid valve is needed. I am eventually leading to that. I just wanted to see a working system for now and work the fine details afterwards. Without the solenoid, i feel like i need to run the rear ac 100% of the time the front is on.

I am very pleased with the results so far. I couldnt have done it without all of you guys. I started with zero knowledge about how the ac system works. Now i still have no clue.lol. Seriously, thank you so much to all.

 

[ARB777]

Nice job, those are pretty good temps given the ambient and idle speed, looks like it was a great success! How does it do around town and on the highway? What's your opinion of the ability to cool the rear, even without the ductwork?

What really made me do this rear ac was my family complaining its too hot in the back rows. Last night they were complaining that it was too cold. We had to turn off the ac the last couple of miles home.

Id say vent temps remained relatively the same on idle, city and highway. Front ranges from 45-55 and rear is consistently at 40.

If i were to do it again. Which i will once my wallet recovers. I would probably go with nissens condenser and the smaller proair unit. The set up i have right now is a bit too much. But then again, i dont have the cut off solenoid so i couldnt turn off the rear.

 

[smritte]

I really wanted to add 2 oz of oil (per proair) but the shop said no need. I read somewhere here that the brand new denso compressor comes with the appropriate amount of oil for the entire system.

Im surprised but, then again Im not at the shop telling you there's no need. As @flintknapper had stated, you need a balance. Most AC systems run around with low oil and all the owner knows is, his went out at 45k where his neighbors went 100k or more. Beside lubing the compressor, the oil coming in the low side cools the compressor. If you ever ran a 2 stroke motor, imagine running with less premix.

As for the "myth" of a compressor coming with a full charge. The modern compressors (after the 80's) don't have an oil sump. That means nowhere to store oil other than all over inside it. On some of the larger orifice tube systems you can have 12-14 ounce of oil and that same compressor on a lesser system holding 8 ounces. Also think hydroloc (spelling?).
Compressors can come with around 2 ounces (ish). I had been told that years ago.

There's a general rule for systems. Almost all compressors take 2 ounce, evap 2 ounce, condensers 1-ounce, lines depend on how long they are. Accumulators and driers are storage tanks, more so accumulator. Accumulator 3-5, driers 1-2. If you add up the "recomended" amounts, you can figure how much the lines need.
You cant forget the small amount of oil that gets removed every time you recover/evac as well as the oil that breaks down over time.

One of the issues I've faced with auto ac is quite a bit of the procedures and some of the data was never updated (think since the 70's).
Ive spent decades working with this stuff and just now I'm seeing the auto manufactures come around. It's tough when I have my students do research and they come up with conflicting info. The industrial ac on the other hand is up to spec as far as Ive seen (only spent a little time there).

Scott

 

[Dissent]

Not bad. Here's mine at 330 pm.


View attachment 1785653

Looks familiar!

 

[Dissent]

What really made me do this rear ac was my family complaining its too hot in the back rows. Last night they were complaining that it was too cold. We had to turn off the ac the last couple of miles home.

Id say vent temps remained relatively the same on idle, city and highway. Front ranges from 45-55 and rear is consistently at 40.

If i were to do it again. Which i will once my wallet recovers. I would probably go with nissens condenser and the smaller proair unit. The set up i have right now is a bit too much. But then again, i dont have the cut off solenoid so i couldnt turn off the rear.

That's great feedback. Is it too cold without the duct work? I don't think the Nissens unit would handle the additional evaporator but I plan on adding the rear unit (same BTU, different mounting setup with the solenoid) around Feb-March when my wallet recovers. My vent temps vary a lot between idle, town and freeway though. 60-45F. I'd rather have too much A/C then the too little I've been living with for 6 years. Trail runs are really where I'm hoping to have it keep the heat at bay. You could always turn up the temp though even without the solenoid right?

 

[Dissent]

What really made me do this rear ac was my family complaining its too hot in the back rows. Last night they were complaining that it was too cold. We had to turn off the ac the last couple of miles home.

Id say vent temps remained relatively the same on idle, city and highway. Front ranges from 45-55 and rear is consistently at 40.

If i were to do it again. Which i will once my wallet recovers. I would probably go with nissens condenser and the smaller proair unit. The set up i have right now is a bit too much. But then again, i dont have the cut off solenoid so i couldnt turn off the rear.

Now that you've had this setup running for a couple of weeks, what's the verdict? Do you have any pics? Does the rear evap have ductwork run? Is it necessary? Where does it route? Overall impressions in traffic? Was it all worth it? Inquiring minds NEED TO KNOW!

 

[ARB777]

It's worth every penny. The problem I am getting is its too cold at night. We always have to bring jackets. This is because I do not have the solenoid to turn off the rear. I think if i dont run the fan, I might freeze up the rear unit as it is constantly getting refrigerant. Eventually I will add a solenoid and dryer to the rear. Probably next summer. For now, my solution is turn off the ac button intermittently while keeping the fans on.

I am trying to see if i have the means to replicate this to my other cruiser. I really want to use the nissens on the next one and the smaller proair 1100 just for the ease of install and less parts to convert. My current system is running so well though that I am kinda scared to change up stuff as well.

I dont have new pics other than the under carriage routing, if you guys want to see that. I tried ducting it with just the flexible spiral ducts proair gave me, pointing it directly to the 2nd row passengers. Those that got direct hit was complaining it was too cold and the ones that didnt was hot. It was working much better without the duct. I think its just too much work to duct it properly to work and my end result would be the same anyway. I also bought ducts that proair uses for limos but I have to pull my headliner. This one being a 94 is a PITA to do and might need a new one after the ducts have been installed. So that part of the project is on hold for now.

I really havent encountered a traffic jam yet and doesnt really happen that much, atleast at times I travel. I couldnt tell any difference in different driving conditions. I just installed a modded blue clutch set at 95* 15k cst. My stock nonmod temp gauge would sit just below half. Before my mod its right at half.

Let me see if can take pictures of the rear with ducts. Mind you, its not pretty. Im not happy with how my rear unit is mounted too but I dont have much of a choice.

 

[ARB777]

That's great feedback. Is it too cold without the duct work? I don't think the Nissens unit would handle the additional evaporator but I plan on adding the rear unit (same BTU, different mounting setup with the solenoid) around Feb-March when my wallet recovers. My vent temps vary a lot between idle, town and freeway though. 60-45F. I'd rather have too much A/C then the too little I've been living with for 6 years. Trail runs are really where I'm hoping to have it keep the heat at bay. You could always turn up the temp though even without the solenoid right?

I dont think Ive answered this. Sorry. I could turn the temp up but I opted not to route the heater lines back. So even though its both cool and heat unit. I am just using it as a cool only unit. I am actually thinking, if I can remove the heating element and modify the box, I could potentially have a unit small enough to fit the quarter panel.

 

[Dissent]

Thanks for the feedback. Great information...I can't believe it's TOO COLD! I've NEVER had anyone say that in my truck.

I understand the fitment issues and the Nissens is a straight bolt-in unit but I don't think you can ever have TOO MUCH condenser in an 80 given the small grill opening. I do wonder if the rear tube 'tees' could be tapped and run off the condenser mount points killing two birds with one stone. Need someone smarter to chime in on this...@flintknapper? I've been eyeballing those hard lines and I would rather overhaul the birfs again than deal with removing them and having them modified.

I'm still sold on the overhead unit mounted on my attic rack. It has built in ducts that I can send forward along the roof line or down on the 2nd row. I won't get any direct cooling below the attic rack but given the open cage design, it should circulate the hot air (rising) nicely. I can't find one small enough to fit between the wall and fridge in the rear corner.

The limo ducts sound intriguing but that soft headliner will be a pain to deal with.