Micro-Tube Parallel Flow Condenser

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@smritte i remember you saying your in the middle of an engine rebuild. This might be the right time to tee your hardlines if you're planning to add a rear unit. Its a pain to remove the hardlines running by the firewall. I would have teed before the front evap for the #6 line but there were so many things to remove so i decided to tee above the fuse box.
 
ARB777 said:
@smritte i remember you saying your in the middle of an engine rebuild. This might be the right time to tee your hardlines if you're planning to add a rear unit. Its a pain to remove the hardlines running by the firewall. I would have teed before the front evap for the #6 line but there were so many things to remove so i decided to tee above the fuse box.
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Im actually considering it. Once the T fittings are in they can be capped until needed.

Scott
 
OP, @Dissent,
I've just read through this saga, great tech, learned a lot, thank you all who are participating! :cheers:

From your first post, I agree, something is not right with your system and could work better with stock components. I am clear that is not why you created this informtive thread.

In my experience, replacing the dryer makes a huge difference, all other variables remaining the same.
They are a consumable item, especially if the system has been opened or non opp for a period of time.

Just cuz I haven't seen it mentioned here, if converting from r12 to 134, you should be shooting for 80% of the lbs recommend in the original r12 system.

Here is the scale I use and it is necessary with a 30lb tank.

https://www.amazon.com/VIVOHOME-Precision-Electronic-Refrigerant-Charging/dp/B075NPMFGF/?tag=ihco-20

Looking forward to to seeing your results when you do finally crack this egg.
 
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@ARB777 the paperwork says 23 oz. If I have time, I might go back on Wednesday to see if their expert can fine tune it.

@Dissent it was PM3903 from Autozone. It did not come with a wheel, but the wheel on your old motor is very easy to remove and obvious as to how when you see it. One thing- this motor doesn't come with the same plug connection as stock and you'll have to either but splice it in, or add male spades to the leads to plug into the factory harness. It's pretty heavy gauge wire on the truck side so you'll need yellow connectors, and will have to fold the conductor of the fan in order to take up the space in the crimp connector.
 
Dindu Nuffin said:
@ARB777 the paperwork says 23 oz. If I have time, I might go back on Wednesday to see if their expert can fine tune it.
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^^^^^^ I would. If he is any good....in 30 minutes he can play with the refrigerant charge and see where the thresholds are. Since they were diligent to record the presently weighed in amount (23 ozs.) then a savvy tech could start out by recovering a few ounces (look for a change in vent temps and pressure) then add back until he reaches the point of diminishing returns (no improvement in vent temps, increase in pressure).

This would establish the 'window' of acceptable charge weight and pressures as well as provide the optimum (for your system) charge under your conditions. So... if ever you needed to evacuate the system....you would have a very good idea where the 'sweet spot' is (refrigerant weight) when recharging.

What did they do for PAG46 capacity? I would think something between 8-9.5 ounces would be about right?
 
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Muggyweld Super Alloy 5 aluminum braze on order.
They've been tempting me for years, but I didn't have any particular application/motivation.
This AC hardline business is perfect for that.
I'm suddenly feeling like I could cobble together a custom AC system from bits and pieces of existing condensers, tube sets, bends, etc.
This thread, and all the great knowledge (& brave pioneering) set forth here, is clarifying many a murky HVAC concept for me.
Thanks all!
 
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@flintknapper I will. Thanks for the push to have it done. I didn't think about establishing what the new charge should be since it's no longer stock... that right there makes me want to do it so that if I ever need to get in there, there's no guesswork on the recharge.

While I have you here- is there any guideline for sizing the evaporator with the condenser? I noticed that the two are almost the same size, with the condenser being slightly larger. Should that roughly 1:1 ratio be adhered to when adding the rear evaporator, or is it more of a trial and error and see what works kind of deal? How would you determine what size rear evaporator you could get away with?

Also, I was poking around in the front of the truck earlier today and started looking at how much room is really in there for a condenser; there's room for another 2" up top and about 3" on either side compared to this Nissen condenser... would it be worth the trouble to find some other parallel flow or... what was the best one... super cool...? 6" wider and 2" taller than this Nissen?
 
Dindu Nuffin said:
@flintknapper I will. Thanks for the push to have it done. I didn't think about establishing what the new charge should be since it's no longer stock... that right there makes me want to do it so that if I ever need to get in there, there's no guesswork on the recharge.

While I have you here- is there any guideline for sizing the evaporator with the condenser? I noticed that the two are almost the same size, with the condenser being slightly larger. Should that roughly 1:1 ratio be adhered to when adding the rear evaporator, or is it more of a trial and error and see what works kind of deal? How would you determine what size rear evaporator you could get away with?

Also, I was poking around in the front of the truck earlier today and started looking at how much room is really in there for a condenser; there's room for another 2" up top and about 3" on either side compared to this Nissen condenser... would it be worth the trouble to find some other parallel flow or... what was the best one... super cool...? 6" wider and 2" taller than this Nissen?
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That extra space is perfectly filled by the Vintage Air Monster SuperCool PF condenser that @ARB777 is working with.
 
Dindu Nuffin said:
@flintknapper

While I have you here- is there any guideline for sizing the evaporator with the condenser? I noticed that the two are almost the same size, with the condenser being slightly larger. Should that roughly 1:1 ratio be adhered to when adding the rear evaporator,

What you will find in most automotive applications it is a roughly 1:1 ratio (Condenser to Evaporator capacity). This is because they must try and satisfy the cooling needs for ALL folks under all conditions in a particular market. Naturally...that means the unit will be suitable for 'most' but not ideal for everyone. The Engineers try to create system equilibrium as much as that is possible. Thermal and Fluid dynamics being what they are...don't always fit nicely as one package in highly variable conditions.

Is it more of a trial and error and see what works kind of deal? How would you determine what size rear evaporator you could get away with?

Well....I wouldn't characterize it as it 'trial and error' except for cases where the installer doesn't understand/appreciate the relationship of Superheat and Subcooling and their effect on system performance.

I understand your question to be: How important is the Condenser to Evaporator ratio and what will happen if I greatly imbalance the two?

We can pretty much dispense with the idea that we can have too much 'condenser' (capacity from a single unit)...simply because there is limited space to install a larger one. The construction of the condenser (flow type) is more important. But let's say you DO have a condenser with marginally greater heat rejection capacity than your evaporators heat absorbing ability.

The result will be slightly less head pressure and a bit better/faster subcooling...but at some point it becomes wasted because the TXV is going to regulate the superheat at the evaporator anyway. While it is good to have well subcooled liquid refrigerant for the evaporator...during times of low to medium heat load, your system will cycle a lot which will affect the ability of the system to dehumidify the air (not a problem for you desert dwellers). ;)

As for evaporators....YES we can have too much imbalance there. IF we were to have significantly greater evaporator capacity than condenser capacity...then things could go to 'hell in a handbag' pretty quickly.

You would be increasing the superheat load leaving the evaporator(s) which might sound like a good thing. However...it results in higher head pressure and greater demand on the condenser (you better have good air flow).


Also, I was poking around in the front of the truck earlier today and started looking at how much room is really in there for a condenser; there's room for another 2" up top and about 3" on either side compared to this Nissen condenser... would it be worth the trouble to find some other parallel flow or... what was the best one... super cool...? 6" wider and 2" taller than this Nissen?

I'll just give you my thoughts on it and let each person decide whether chasing down the 'ultimate' condenser is worth the efforts required to install/adapt it.

Some considerations:

1. What will be involved in terms of installation (easy, moderate, wish you'd never seen it)?
2. What percent larger is the unit (of same flow type) than the one removed?
3. As installed...are the increased frontal and exit areas actually in the air flow stream or are they sitting over mounts and other obstructions?
4. Is the increase in efficiency in balance with the capacity of the evaporator(s) or is it being wasted?
5. If damaged...can you get a replacement and how long will it take?

Bottom line: It is best to have closely matched capacities (condenser & evaporator) but it will not hurt to have a 'slight' imbalance in favor of the condenser.

The average rear air installation is not going to perform quite as well as the front unit (expect 8-12° difference). It might also prove slightly parasitic to the front unit (so you want a solenoid valve when rear is not used/needed). BUT....if you can get relatively cool air circulating around the passengers/pets in the rear...most are going to be happy campers. The one's that aren't... can get out and walk.
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^^^^^^ expand for replies.
 
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ARB777 said:
Proair air tech 2. Its huge. And its a problem. To retain 3rd row seating, I would have to mount it behind the seat as pictured. Impossible to mount it to the quarter panel like the oem unit. I looked at the smaller proair 1100. Even though its slimmer it still wont fit with the seats folded up.

View attachment 1769006

View attachment 1769007
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What about this trunk mounted unit instead. Looks like it may fit in the quarter panel possibly.
SPECIAL APPLICATIONS Vacuum Universal Systems - Vintage Air
 
Dindu Nuffin said:
@flintknapper I will. Thanks for the push to have it done. I didn't think about establishing what the new charge should be since it's no longer stock... that right there makes me want to do it so that if I ever need to get in there, there's no guesswork on the recharge.

While I have you here- is there any guideline for sizing the evaporator with the condenser? I noticed that the two are almost the same size, with the condenser being slightly larger. Should that roughly 1:1 ratio be adhered to when adding the rear evaporator, or is it more of a trial and error and see what works kind of deal? How would you determine what size rear evaporator you could get away with?

Also, I was poking around in the front of the truck earlier today and started looking at how much room is really in there for a condenser; there's room for another 2" up top and about 3" on either side compared to this Nissen condenser... would it be worth the trouble to find some other parallel flow or... what was the best one... super cool...? 6" wider and 2" taller than this Nissen?
Click to expand...
I have a scale on the way and will most likely be working on this next weekend. Let me know if you get anything more final than 23oz or get a range window. Did they give you a total PAG46 capacity?
 
flintknapper said:
^^^^^^ I would. If he is any good....in 30 minutes he can play with the refrigerant charge and see where the thresholds are. Since they were diligent to record the presently weighed in amount (23 ozs.) then a savvy tech could start out by recovering a few ounces (look for a change in vent temps and pressure) then add back until he reaches the point of diminishing returns (no improvement in vent temps, increase in pressure).

This would establish the 'window' of acceptable charge weight and pressures as well as provide the optimum (for your system) charge under your conditions. So... if ever you needed to evacuate the system....you would have a very good idea where the 'sweet spot' is (refrigerant weight) when recharging.

What did they do for PAG46 capacity? I would thing something between 8-9.5 ounces would be about right?
Click to expand...
Per the FSM: System Capacity of PAG46 is 7.6oz (224cc) total.
 
Dindu Nuffin said:
Well boys, the tech said he got 42°F out of it and said that the AC expert they have come in on Wednesdays could probably get it down a little lower if I wanted to come back.

My knuckles were freezing on the way home and for the first time, I had to take the fan off high and redirect the ball blower. I'm really looking forward to being able to hit the trail without suffering the heat and the dust.

The real test will be taking it to work on Monday and letting it sit out in the heat all day followed by the first ten minutes of my commute being sub- 10 mph speeds. I'm stoked. :-D
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I don't know your timezone but I'm anxious to see if you had a chance to test it on the drive home yet?
 
the oil was a guess. they asked me about the oil when I was handing them the keys, and I said that I basically replaced everything except the lines and compressor. I didn't see that much oil come out of what I replaced, but the drier sounded like it had an ounce or so when I shook it. So, I said to add two ounces.

I'm in the Mountain Time zone, and I didn't drive it yesterday or today. As luck has it, it's only going to hit 89° once this week- on Friday, my day off. I am going wheeling on Sunday, which is supposed to only be 86°, but that's all low speed stuff, and that's where I was having the 2nd biggest issue with the AC. I'll go out after work today and put a thermometer in a vent and see how long it takes to hit various temps. I am driving it tomorrow so I can swing by the shop on the way home to let their 30 year AC tech fine tune it and I'll let you know what the final charge is.
 
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