Front AC condenser and R-134 conversion.

quote:

There is no way available to the average A/C shop for them to tell what gas is in your system.

If I can manage to have one of these on my garage shelf, I imagine an average A/C shop could have one.

A standard R/R/R unit has only one recovery tank. No shop will knowingly contaminate that tank with any of the R-12 substitutes on the market.

Yes, the substitutes 'work'. But innocently mention you've added them to your system, and the shop will likely decline to work on it.

Larry

quote:

If you want to play around with your A/C system and do repairs, mods, updates ect, buy a recovery unit.

It will make your life much more pleasant. You will be able to pump out your system, save the gas, work on it, fix leaks, vacuum pump it, recharge it and all at your own leisure, no rush trips to the A/C shop and you'll only need to do that a few of times and it will pay for it self. I've had to pump my system out and recharge it a few times in a day in the effort to seek out a elusive slow leak (the hardest to find) that would have cost me a bundle if i had to do it through a shop.

The R-12 R/R/R units are now dead weight at most shops. They are regularly seen on eBay and Craig's list.

Shipping expense is a deal killer, but find one locally and negotiate the price down to your comfort zone.

As Aus Ford wrote, they can easily pay for themselves when you have a slow leak or are re-doing your A/C system.

Larry

quote:

Originally posted by LF - TP 2511:

quote:

There is no way available to the average A/C shop for them to tell what gas is in your system.

If I can manage to have one of these on my garage shelf, I imagine an average A/C shop could have one.

A standard R/R/R unit has only one recovery tank. No shop will knowingly contaminate that tank with any of the R-12 substitutes on the market.

Yes, the substitutes 'work'. But innocently mention you've added them to your system, and the shop will likely decline to work on it.

Larry

I simply would not tell them.

I'd say i don't know what's in the system. Leave it to them to work it out and deal with it appropriately.

They have the means to deal with contaminated R-12, 99% of all systems that came in would be contaminated with something and so would not contain pure R-12.

Contamination is a well known problem and recyclers collect and purify used refrigerants for reuse.

Anyone that refuses to is acting purely for their own self interest and not because of some technical impossibility.

Anyone that expects to recover pure R-12 or any other pure refrigerant from a automotive A/C system is kidding themselves. By design Auto A/C systems are prone to contamination. I would expect to recover contaminated gas from all Auto A/C systems, not expect to recover pure refrigerant. They are kidding themselves.

I most certainly not encourage anyone to deliberately dump refrigerant of any type to atmosphere.

Maybe the best thing is ask the shop if they handle contaminated refrigerants and send them for recycling ?

Photo of a coiled compressor discharge line that replaced a rubber hose.

Aus Ford,

Thanks for the great information. I was particularly interested in your suggestion to use the larger Sanden SD7H15 compressor.

It seems that sometimes we Pantera owners use a particular item because it's just what everyone else uses. No one stops to ask "why" and/or "is there something better"? Perhaps the SD508 is such an item.

quote:

use the larger Sanden SD7H15 compressor.

I installed this unit last year, on the recommendation of John Buckman. Same physical mounting as the older Sanden that has been used for years by Pantera vendors.

If you are replacing the York, you'll need the same adapter plate used and sold by the vendors, and numerous eBay sellers.

It comes with o-ring fittings, but if you still have the stock flare fittings under your dash, all you need is the little "acorn" adapters to convert to serviceable flare fittings.

If you use R-134a then the factory supplied oil is fine. If you are still using R-12, you'll need to drain the factory oil and refill with R-12 compatible oil.

This outfit has sold several units to Pantera owners. They will toss in the adapters if you ask, and their pricing is likely as good as you will find.

Larry

This is not in a Pantera but it is on a Cleveland engine. I'm assuming Pantera's mount the York compressor in the same position.

This is a photo of a SD7H15 (on the right) mounted in the same position as the York was using a adapter on the old York bracket.

The SD7H15 automatically runs faster than the York since the SD7H15 pulley is smaller than the York pulley. So no mods are required to achieve the slightly faster compressor RPM that is desirable.

On the left is a SD508 that is used as a air compressor in this installation (for pumping up tyres) Note the size of the two compressors is the same depite the SD7H15 having 20% more capacity (2 extra cylinders).

The owner of Vintage Air wrote a book on AC systems. I read part of it when I was engineering my sysytem. In it he discusses the how to pick the proper size displacement for your AC pump. He specific points out that the Sanden 7 series is to large for most auto applications. Unfortunately, I do not recall his reasoning. However, his publication is available or a call to Vintage Air would probably suffice. The 5 series was a better solution.

I'm simply addressing the point that someone was making about failure of others to think outside the box and following blindly the decision of others like lemmings. Actually, some past decision were based on research whether accurate or not. Bigger not always better.

JT,

Here's a paragraph that's taken from the Vintage Air catalog:

"Compressor Capacity Is Critical
Capacity is critical in selecting a compressor.
Why? The weak link in most aftermarket
air conditioning systems is the condenser's
ability to handle the demands of the other air
conditioning system components. These
demands are to condense the refrigerant
enough to keep the compressor head pressure
and corresponding refrigerant temperature
within acceptable operating limits (approx.
twice the ambient temperature of the day, plus
fifteen percent) and to supply the evaporator
with adequate refrigerant. Generally speaking,
if a compressor has too much capacity the
result will be excessive high-side pressure and
temperature, compressor damage and excessive
load on the engine. If a compressor has
too little capacity the system will suffer inadequate
evaporator performance. Our basic minimum
given in the condenser part of this article
is larger than most aftermarket systems
are using; however, we will use that as our
standard size condenser. A compressor of 8
or 8.5 cubic inches of displacement per revolution
is ideal for a classic car or truck with
our standard size condenser, and an average
size aftermarket evaporator (approx. 200
cubic inches of coil mass). We would always
lean toward a smaller compressor before
going to a larger one."

quote:

Originally posted by David_Nunn:

A compressor of 8
or 8.5 cubic inches of displacement per revolution
is ideal for a classic car or truck with
our standard size condenser , and an average
size aftermarket evaporator (approx. 200
cubic inches of coil mass).

We would always
lean toward a smaller compressor before
going to a larger one."

If you are replacing a 10.5 cubic inch compressor (York) in a old system you should replace it with another compressor of the same or very similar capacity, not one that is 20% smaller (SD508).

You would have to run the SD508 a lot faster than the York to make up the capacity shortfall and that just unnecessarily introduces more heat to the system from heat of compression and internal compressor friction that must the be dumped by the condenser in addition to the condensers normal load.

If also you intend to change refrigerants from R-12 to R-134a you the place a further requirement on the compressor as you will need to move a greater amount of R-134a through the system than you did R-12 because the properties of the two refrigerants are slightly different.

R-134a boils at a slightly higher temperature than R-12 (so it doesn't get as "cold") for any given evaporator pressure and also R-134a does not transfer the heat as well as R-12, so to move the same amount of heat as a given amount of R-12 more R-134a needs to be moved.

Think of A/C as a conveyor belt for heat.

You put heat on the conveyor in the cabin of your car, the conveyor takes it outside, then the heat is dumped to the passing air. The conveyor belt continues back to the cabin with the heat removed where you can put more heat on it to be moved outside.

If you have a big wide conveyor belt you can fit more heat on it, thus move more heat in any given amount of time, if it is small and narrow only a small amount of heat can fit on it, so you only move a small amount of heat in any given time.

Refrigeration is all about system capacity.

R-12 boils at -29.8 degrees C and R-134a boils at -26.1 degrees C (at 14.7psi absolute pressure), so it looks as if doesn't get as "cold". That's true it doesn't but -26.1 would be "cold" in anyones language so why doesn't it feel as cold in your car ?

Think of it this way, if we could get your car's interior down to 0 degrees C (32F) most people would say "gee wiz it's jolly cold".
A ice cube from your freezer is at 0 degrees C, but putting one ice cube in your car would have no effect on the temperature in your car you could possibly feel. But what about 1000 ice cubes ? Or 2000 ? Or 5000 ?

At some point if you continued to place ice cubes inside your car the interior temperature would fall to 0 degrees C.

This is capacity.

No ice cube is colder than 0 C, one ice cube does nothing to make you feel cool, but 5000 will. The temperature of the refrigerant hasn't changed but the amount of refrigeration has.

I have heard people say they are disappointed with a dashboard vent temperature of 15 degrees C and they want it "colder" say 2 degrees C. The reality is they don't really need it "colder", if all the air in the car could be maintained at 15 C they would feel cold.

Imagine if the A/C in your house or office was set to 15 C you would have to wear a coat or jumper.

What the car A/C needs is capacity.



As the article extract in the previous post said "Compressor Capacity Is Critical", it must be a match for other components in the system. Not too big , not too small. So if your current system has 10.5 cubic inches of compressor capacity replace it with as close to 10.5 cubic inches as you can. Not 20% smaller.

In the article extract they talking about new systems they are building up from scratch.

They have the luxury to choose the refrigerant from the word go, not try to get a refrigerant to work in a system designed for a refrigerant with different properties.

They can also choose condenser and evaporator designs and capacities at will, not be stuck with using what is already in the car or what could be reasonably expected to fit and in those circumstances with the components they use the SD508 may very well be suitable.

They may also have a stockpile of SD508's they want to get rid of.........Don't be fooled, financial incentives are more powerful than engineering ones when it concerns this "black art" of refrigeration. Many many customers have been made to purchase things they don't need or things not up to the task by car A/C mechanics preying on the average customers ignorance.



The Sanden compressors of any capacity run much nicer than the clanky old York. As i have said the small sacrifice of 0.5 cubic inches when replacing a York with a SD7H15 is worth it to get the SD7H15's smoothness.



.

quote:

Originally posted by LF - TP 2511:
Thanks, Scott.

As expected, what you received from Steve is a tube and fin style. That is the same unit I used.

A LOT of folks, sadly vendors included, somehow have gotten the wrong idea of what constitutes a "parallel flow" style.

Larry

Thanks for the replies and valuable discussion. –Very helpful.



The evaporator above looks like re-worked OE unit that borrows the position of one of the heater core coil stacks and uses it to increase the overall AC evaporator coil mass.

Does anyone know the evaporator coil mass of this or the stock OE unit? Alternatively, even just the overall L x W x H dimensions of the entire core would suffice in making a decent estimate for either unit. If anyone has that information a reply post would also be greatly appreciated.

The unit above and the OE unit appear to be slightly different in the configuration of the evaporator expansion circuit and this eBay unit below appears to be the same expansion circuit approach as the OE unit, except with the additional coil mass has been devoted to the evaporator similar the modified unit pictured above. It’s a big price for an evaporator/heater core.

http://www.ebay.com/itm/DeToma...em3ccbe71928&vxp=mtr

The following is just my take on the matter but with proper selection of the rest of the system components, I think sufficient performance can be achieved (at least that of the OE system) from R-134a, sticking with the OE evaporator, and utilizing a higher performing condenser in the much cooler greater airstream at the front of the car. I think the biggest challenge to the performance of the OE Pantera AC system design was the condenser sizing, location, and generally poor condenser fan performance. A better condenser and fan in the OE location would likely significantly improve the OE configuration performance for any refrigerant, but for a given coil mass you’ll never have the potential condenser performance that can be achieved in the front of the car, at least at speed, and probably under all conditions.

In my experience the overall OE Pantera system performance was adequate when it was at full charge (R12) and operating properly. So, I think the OE evaporator coil is probably sufficient if the rest of the system is at least equal the performance of the OE system, which I think can be easily improved. With properly selected components and control scheme I don’t think R12 or R134a is material.

A couple other observations on the compressor sizing discussion earlier in the thread; all of the displacements referenced for the York, and Sandens are the swept volume or displacement per revolution. You can’t properly size the compressor without also considering the compressor operating speed.

The pulley diameter on my old York style recip compressor is about 6” while that on my Sanden 508 is 5”. The York pulley size was evidently selected for the 5 1/2” Pantera (but also std sbf size) crank pulley. So the original compressor was underdriven and concluding that 10.5 cubic inch compressor is required neglects the intended drive speed. Since changing the crank pulley diameter would change the drive speed and performance of everything else it’s driving, common practice is to size the driven pulleys for intended operating speed of the accessories.

It so happens that though an 8.5 cubic inch swept displacement Sanden 508 compressor is 20% less than the York’s, but with the Sanden OE pulley, it will operate at ~20% higher speed than the York and thus have comparable pumping displacement, assuming similar volumetric efficiency, for any given engine speed. I don’t think that’s a coincidence? So yes, you do need to run the Sanden faster but I would contend Sanden’s wobble plate piston compressors are designed to run faster and 20% faster than a York unit is certainly no stretch for them. As near as I can tell, virtually all Sanden wobble plate passenger car compressors come with this a 5” pulley. According to the Sanden manual, all Sanden wobble plate compressors are rated for continuous operation at 4000 RPM and many 6000 RPM. This is compressor speed not engine speed. With a 5.5” sbf crank pulley, a (Sanden) compressor with a 5” pulley will run ~10% slower than engine speed. I will never approach that continuous compressor operating speed and only see excursions to 7krpm or so and when doing so will not likely bring the AC along for that portion of the ride. I have a high speed cut out but usually just turn off the AC for spirited driving.

With a displacement of 155cc/9.5 in3, the Sanden SD7H15 is largest displacement passenger car compressor Sanden offers. Now I certainly note and agree with more cylinders means smoother pulses/operation, and slower operating speed means longer life, but in my view unless you were going to increase the drive pulley diameter to enjoy those benefits, I just can’t imagine why it would be needed in a Pantera. I’d contend the Pantera has more modest overall AC capacity needs than most passenger cars for the following reasons. First, being a two-seater, the passenger compartment in a Pantera is small compared to full size passenger car. It has much less volume and less window area which means less solar load, and at most two people to keep happy. It does have close passenger proximity to the engine compartment firewall, but front engine cars not only have an entire firewall they also typically have the additional heat load from undercar exhaust, transmission, and engine heat passing under the car. In a Pantera, if you insulate the firewall (I have done so) you’ve probably taken care of the majority of the addressable heat load. Next the floor (I just have the factory Jute) and then the doors (I have nothing). Though you could undoubtedly get improvement (both thermally and acoustically) with attention to the latter two, I think very satisfactory results can be achieved without further insulation beyond the firewall.

There are downsides to installing a larger pumping capacity compressor than needed. More capacity means more power to drive it and this can lug engine speed down at idle and cause erratic idle problems. In addition to understanding how the pulley and drive belt scheme affects compressor drive speed, when comparing AC systems and components from one vehicle to another, what will be engine idle and cruise speed. It’s not a trivial matter because the compressor speed is proportional to engine speed, and in almost all cases the biggest challenge to the cooling capacity of any AC system is with the engine at idle and car at rest….it’s the lowest engine speed (refrigerant compression/expansion/flow), lowest air flow across the condenser, and the highest effective ambient temperature due to parasitic short circuiting of cooling air with engine compartment and pavement heat.

In my case, I will pay some price in overall engine cooling capacity for having the condenser in front of the radiator but I have a Ron Davis radiator and it’s just a great piece work. The guy makes a great radiator. Even at twice the OE HP I think I’ll be just fine for my use. If I was running the Silver State and at max power for prolonged periods I may take pause installing the condenser in front of the radiator……but, I’m not. It’s just a street car or it wouldn’t even have AC. -I’ll let you all know how it turns out.
On the subject of relative refrigerant performance and efficiency, here is succinct summary by a notable manufacturer and I’ve found it to be consistent with all the other technical sources. Pay particular attention to sections 1a-d, but especially 1d.

http://www.tecumseh.com/~/medi...ization-of-R134a.pdf

Another useful document for technical information regarding Sanden Compressors:

http://www.sanden.com/objects/...Service%20Manual.pdf

BTW Aus Ford, I really like your use of that SD508 as an onboard air compressor……very clever…..good on ya.

Best,
K

[QUOTE]It’s a big price for an evaporator/heater core.

http://tinyurl.com/qxhj47d


WELL!!

Same unit.

Same seller.

But they used to sell that unit, IIRC, for either $499 or $599.

Now it is $899 !!!???

I imagine since the value of our cars is going up, the scoundrels in the aftermarket world will now be jacking up their prices, too.

May the fleas of a 1000 camels infest their private regions.

Larry

Larry, the flea quote from "Carnac the Magnificent" aka Johnny Carson if I remember right is great. Brings back great memories. And yes, stick it to some of the not so good aftermarket scoundrels!
Ken

quote:

Originally posted by Panterror:

BTW Aus Ford, I really like your use of that SD508 as an onboard air compressor……very clever…..good on ya.

Best,
K

I used to live in a rural area many miles from a gas station and transport so to have the ability to pump up the tyres any where was a real Godsend.

It's simple to do and works really well.

You just need to set up a simple dry sump lubrication system for it as A/C compressors are lubricated by oil travelling through the system with the refrigerant.

Obviously that doesn't happen with air and you can't fill the sump with oil as SD508 doesn't have one and any level of oil in the compressor would back up against the bottom cylinders go past the single compression ring (no oil scraper) and be pumped out with the compressed air.

We could start a whole thread on this. PM me if you re interested in more detail.

quote:

Originally posted by Bosswrench:
Inside the evaporator valve is a sliding plug and a spring; the spring may be different strength than in an OEM valve for R-12. And of course the tiny conical screen filter in the side-leg is usually removed from r-134a installations. That screen catches a lot of powdered debris from ancient dryer cannisters, so maybe with R 134a one should change dryers every so often? Or put the screen back in and see how it affects coolness?

Does anybody have any photos of the tiny conical screen filter and its location?

quote:

Does anybody have any photos of the tiny conical screen filter and its location?

You mean like this?

Larry

Excellent, thanks

Lots of good info .I am looking to move AC condenser to front of car too. the question I have. Is it better to run pipe under car or try to run threw door pan ? Just thinking it may get very hot with radiator pipes and back top heat on it .Has any one tried to run pipe that way. I know under car would be a lot quicker. I returned the condenser 14 x 18 I purchased from summit /vintage air . I ordered the 12 x 20 the 14 x 18 inch will only fit in my car if i move radiator bottom back . think the 12 x 20 will fit better . I was also told to have at lest 1 inch gap from condenser and radiator for better cooling.

quote:

Originally posted by pantera74Bills6976:
Lots of good info .I am looking to move AC condenser to front of car too. the question I have. Is it better to run pipe under car or try to run threw door pan ? Just thinking it may get very hot with radiator pipes and back top heat on it .Has any one tried to run pipe that way. I know under car would be a lot quicker. I returned the condenser 14 x 18 I purchased from summit /vintage air . I ordered the 12 x 20 the 14 x 18 inch will only fit in my car if i move radiator bottom back . think the 12 x 20 will fit better . I was also told to have at lest 1 inch gap from condenser and radiator for better cooling.

Under the car is simple to do with a hardline...