A/C Compressor

[Stuartc]

Could I ask someone who has factory A/C fitted to their X1/9 let me know what the make/model number (important) that was fitted from new please? Picture of any identifying code would be even better.

I’d be interested in both early (York I believe?) and later models (Sanden I Believe?).

WHY?

Like to know what the capacity “CC” that was fitted from factory as they’re usually matched to the other components including the “cooling capacity” required for each individual application’s interior.

This way I can make a more objective choice of electric, scroll or swash plate piston compressor which come in many capacities, fixed and variable!

Thanks in advance

 

[ng_randolph]

This is the A/C compressor on my '85:

 

[Stuartc]

Thanks for confirming it was a Sanden 508 unit just wanted to be sure.
508 therefore 5 piston, 8 CU or 131 CC’s surprisingly that’s a fairly large capacity considering the x1/9’s interior.!

 

[ng_randolph]

Thanks for confirming it was a Sanden 508 unit just wanted to be sure.
508 therefore 5 piston, 8 CU or 131 CC’s surprisingly that’s a fairly large capacity considering the x1/9’s interior.!

Even a tad larger than that, my manual lists it as 138 cc.

 

[Stuartc]

even Sanden are saying “approximately”.
All good information, thanks!
Trying to figure out the best way to go ie efficiency!
Electric (12v) would be ideal but I’m not convinced a 12v (18-22cc) compressor is going to seriously have a chance (we had 46 here this week, that’s approx 115f).
Scroll is looking like the best way to go only down side and is “idle” performance I think!
Still looking into wobble/swash plate piston, fixed v variable capacity but definitely 7 piston as I think they’re “more efficient” less power drag per rotation.

 

[Dr.Jeff]

Yes, I can confirm the factory compressor was a Sanden 508. Fortunately that is the most common "universal" unit used for most aftermarket systems, hot rods, custom cars, etc. So it can be found easily and rather affordably.

Where I live the temps are quite similar to yours so I'm familiar with your concerns about keeping the car comfortable. The X's cabin is very small with few cubic feet to cool. I think just about any compressor will do if you add some interior insulation wherever possible. Also the compressor will need to match the condenser. The original Fiat condenser was undersized for the 508. And it was a very inefficient type. Utilizing a much larger aftermarket "parallel flow", high efficiency universal replacement will significantly improve the cooling capacity of the system. Same with utilizing better electric cooling fans up front.

There's a "baby" version of the 508 available. Off hand I don't recall the model name but it looks like the 508 only smaller. The advantage is less load (power draw) on the engine. I imagine it may not be difficult to adapt the stock compressor mounts to accept this one, making the swap easy if your car already had AC. Or there are some small compressors used on such cars as Kias, Hyundais, etc. However most modern units are fitted with serpentine belt drive pulleys, so they mount solidly to the engine block.

Definitely delete all of the factory temp, pressure, and freeze sensors if you are refurbishing a factory AC system. A trinary switch on the receiver/dryer will be a excellent upgrade.

 

[Steve Thomas]

Bear in mind that the original AC system was back in the days of nasty refrigerants. You will have to [no choice at all] use a modern refrigerant. So, that means you need to look at all components in the system. Seal compatibility, flows, pressures etc.

EDIT - rereading the above, I could have been clearer You can just use all original components or a mix of old and new or all new. But in all cases, you can only use a modern refrigerant. That means that an all original system or a mixed system will probably have lower performance than original ex-factory - refrigerants ain't refrigerants.

 

[Dr.Jeff]

Bear in mind that the original AC system was back in the days of nasty refrigerants. You will have to [no choice at all] use a modern refrigerant. So, that means you need to look at all components in the system. Seal compatibility, flows, pressures etc.

True. As a result, I would not recommend using any of the original hoses as they hold a lot of old refrigerant in the material lining the inside. Not to mention they likely leak. Besides, the original lines had all of those horrible sensors and such that you will want to eliminate, and therefore a lot of extra fittings you won't need. Naturally you also don't want to reuse the old receiver/dryer (filter).

Basically I replaced everything with new universal components; compressor, condenser, receiver/dryer, expansion valve, hoses, etc. The only factory item left in the entire system is the evaporator due to its unusual size/shape. New ones can be made but are quite costly. Mine was in good condition so I thoroughly flushed it and refit it with new seals (of proper material for the new refrigerant).

This is why I stated earlier that it really isn't that difficult to add AC to a non-AC car. Basically you will be using all new universal components that are readily available and affordable. The only Fiat components that will make the installation easier are the mounting brackets for the compressor and the AC style heater box (with evap). You can either swap in the dash controls for the AC heater box or do what I did and convert them to manual controls (I hate vacuum controls). The couple of factory parts needed should be easy to find due to lots of owners with AC wanting to remove it.

 

[ng_randolph]

even Sanden are saying “approximately”.
All good information, thanks!
Trying to figure out the best way to go ie efficiency!
Electric (12v) would be ideal but I’m not convinced a 12v (18-22cc) compressor is going to seriously have a chance (we had 46 here this week, that’s approx 115f).
Scroll is looking like the best way to go only down side and is “idle” performance I think!
Still looking into wobble/swash plate piston, fixed v variable capacity but definitely 7 piston as I think they’re “more efficient” less power drag per rotation.

@LarryC documented his work on upgrading / refurbishing his A/C in this thread, and especially the continuation here. Worthwhile reading before doing any work on the X1/9 A/C.

In the mid 90's, when R134a was new, opinions differed on how much work was needed to retrofit older R12 systems. VW published Technical Bulletin 95-03, saying essentially, drain as much of the old oil as possible, replace the receiver / dryer, replace any O-ring that was disturbed, evacuate and refill with PAG lubricant and R134a. Sanden publish similar guidelines.

 

[kmead]

There are also the systems created by Rodger and Hussien for their K swapped cars. Both offer good guides in regards to what was done, how it was done and why.

I followed the VW bulletin when I converted my 1991 VW Passat over to R134a and the system worked well for another decade.

 

[MikeHynes]

Bear in mind that the original AC system was back in the days of nasty refrigerants. You will have to [no choice at all] use a modern refrigerant. So, that means you need to look at all components in the system. Seal compatibility, flows, pressures etc.

EDIT - rereading the above, I could have been clearer You can just use all original components or a mix of old and new or all new. But in all cases, you can only use a modern refrigerant. That means that an all original system or a mixed system will probably have lower performance than original ex-factory - refrigerants ain't refrigerants.

No choice at all? Why? Required by law? R12 is still available. It's not readily available, but can be found. And, there are still shops out there that can service it.
But...especially for a new install it's best to use modern refrigerants. Save the R12 for the old cars.

 

[Steve Thomas]

No choice at all? Why? Required by law? R12 is still available. It's not readily available, but can be found. And, there are still shops out there that can service it.
But...especially for a new install it's best to use modern refrigerants. Save the R12 for the old cars.

In Australia, recharging with R12 is illegal and OP is in Australia.

 

[Stuartc]

The plan is to use all the interior parts and pretty much update the rest apart from the OE radiator/condenser fans which are fundamentally very effective. Only downside to the original rad/condenser fans are they’re “brushed” and possibly a bit amp hungry which possibly could need updating if I decide to go electric scroll compressor.
Done away with heater tap and cable and replaced with a more modern linea pot and motorised heater tap!

New receiver/dryer courtesy of JLR as it’s identical to original and has a port to fit modern Trinary switch for High/low & condenser fan triggers. In my case updated the system so that the rad & condenser fans are activated on a “resistive circuit” on the A/C system being energised and the trinary switch controls the “High Speed” circuit (non resistive) when/if required.

All barrier hoses to be replaced with R134a specific hose. As all “non-R12” refrigerants are a smaller molecule than the R12 refrigerant you must change the barrier hose otherwise you’ll need to regas on a regular basis due to gas loss.
Same with all the original pressure sensors must be replaced as the temp/pressures are different between R12/R134a rendering them useless.
Anyhow I’ll update my progress on the following topic,

Air Conditioning Retrofit RHD

There are threads covering air conditioning retrofit but this is for a RHD vehicle ROW in my case for Australia on an “88 Bertone. Rather than covering similar already covered info on LHD retrofits if anyone has any specific questions on a RHD conversion (remember ROW RHD models never had...

xwebforums.com

The purpose of this thread, after establishing that the original Sanden 508 was a 138cc capacity is to choose a more modern/efficient compressor using the base line of 138cc being what originally was considered to be necessary discharge capacity to cool the X1/9’s interior.

Unfortunately this may only be relevant to engine crank driven compressors only and not to something like an electric compressor which runs at a constant 4500rpm as in the Rencool 12v compressor I’m looking at. With a specification of only 18cc per revolution it is far smaller than the Sanden crank driven compressor at 138cc per revolution.

The difficulty part here is comparing as the crank driven compressors are operating over a varying range of rpm and as such has some level of “inefficiency” built in to prevent damage at high rpm, whereas the electric compressor (scroll) does not!

Open to discussion as I’m still scratching my head and trying to, if possible find some way of comparing a constant driven v variable driven compressors!

 

[Dr.Jeff]

I would not make the assumption that Fiat selected the Sanden 508 based on its refrigerant capacity, nor on the car's interior cooling needs. More likely it was what they could get cheap and readily for the rather cobbled together AC system they threw into these cars. Actually I think the 508 is too big for such a tiny cabin (few cubic feet of air to cool). And too big for the under powered engine to effectively handle. So I would not base all of my design requirements on the 508. Just my opinion.

As for "scroll" type compressors. I've had a couple of vehicles (non-Fiat) that came with them as part of the factory AC system. And they were not particularly great. I found them to be less effective in a really hot climate (compared to a more traditional design compressor), and they had rather short lives - needing to be replaced every few years (which conventional compressors did not). However I can't say how those factory scroll compressors compare to the ones you are considering, perhaps there's a major difference.

 

[ng_randolph]

The plan is to use all the interior parts and pretty much update the rest apart from the OE radiator/condenser fans which are fundamentally very effective. Only downside to the original rad/condenser fans are they’re “brushed” and possibly a bit amp hungry which possibly could need updating if I decide to go electric scroll compressor.
Done away with heater tap and cable and replaced with a more modern linea pot and motorised heater tap!View attachment 81895
New receiver/dryer courtesy of JLR as it’s identical to original and has a port to fit modern Trinary switch for High/low & condenser fan triggers. In my case updated the system so that the rad & condenser fans are activated on a “resistive circuit” on the A/C system being energised and the trinary switch controls the “High Speed” circuit (non resistive) when/if required.
View attachment 81896

All barrier hoses to be replaced with R134a specific hose. As all “non-R12” refrigerants are a smaller molecule than the R12 refrigerant you must change the barrier hose otherwise you’ll need to regas on a regular basis due to gas loss.
Same with all the original pressure sensors must be replaced as the temp/pressures are different between R12/R134a rendering them useless.
Anyhow I’ll update my progress on the following topic,

Air Conditioning Retrofit RHD

There are threads covering air conditioning retrofit but this is for a RHD vehicle ROW in my case for Australia on an “88 Bertone. Rather than covering similar already covered info on LHD retrofits if anyone has any specific questions on a RHD conversion (remember ROW RHD models never had...

xwebforums.com

The purpose of this thread, after establishing that the original Sanden 508 was a 138cc capacity is to choose a more modern/efficient compressor using the base line of 138cc being what originally was considered to be necessary discharge capacity to cool the X1/9’s interior.

Unfortunately this may only be relevant to engine crank driven compressors only and not to something like an electric compressor which runs at a constant 4500rpm as in the Rencool 12v compressor I’m looking at. With a specification of only 18cc per revolution it is far smaller than the Sanden crank driven compressor at 138cc per revolution.
View attachment 81897
The difficulty part here is comparing as the crank driven compressors are operating over a varying range of rpm and as such has some level of “inefficiency” built in to prevent damage at high rpm, whereas the electric compressor (scroll) does not!

Open to discussion as I’m still scratching my head and trying to, if possible find some way of comparing a constant driven v variable driven compressors!View attachment 81898

This document shows the performance of various Sanden compressors. The SD5H14 would be the one closest to the SD508 in capacity (both listed as 138 cc / revolution, both being 5 cylinder units). The graph shows about 5 kW of cooling capacity at 2000 RPM (reasonable cruising speed). Looking at the X1/9 pulley sizes, compressor speed and engine speed are about the same (corroborated by the Sanden spec of max allowable speed of 6000 RPM continuous / 7000 RPM peak). The 12V Rencool unit has less than half that (2.15 kW) at peak RPM. The SD508 may be generously sized for the X1/9, but having less than half that capacity in a hot climate would worry me.

The other problem is power draw. The Rencool at 3000 RPM (and only 1.38 kW of cooling capacity) draws 0.74 kW of electrical power. That comes out to 53 Amp at 14V. The Bosch alternator rated 65 Amp produces only about 45 A at 2000 RPM, so unless you get a much larger alternator, you don't have enough electrical power to run the 12V Rencool even at 1.38 kW of cooling capacity.

I have looked somewhat casually at alternative A/C compressors. Sanden SD5Hxx and SD7Hxx are available in configurations that would make them drop-in replacements for the SD508 (at least for mechanical mounting). I have not seen any scroll compressors with SD508 style mounting ears, so a tensioner bearing setup would be needed.

It looks to me like anything other that dropping in an SD7Hxx or SD5Hxx would increase the effort required dramatically without providing a commensurate improvement in performance.

Incidentally, I know someone who refurbished his X1/9 A/C system much like @LarryC did in the threads I referenced earlier (larger condenser, new wobble plate compressor, new JLR receiver drier, R134a) and the system works very well.

 

[Stuartc]

I would not make the assumption that Fiat selected the Sanden 508 based on its refrigerant capacity, nor on the car's interior cooling needs. More likely it was what they could get cheap and readily for the rather cobbled together AC system they threw into these cars. Actually I think the 508 is too big for such a tiny cabin (few cubic feet or air to cool). And too big for the under powered engine to effectively handle. So I would not base all of my design requirements on the 508. Just my opinion.

As for "scroll" type compressors. I've had a couple of vehicles (non-Fiat) that came with them as part of the factory AC system. And they were not particularly great. I found them to be less effective in a really hot climate (compared to a more traditional design compressor), and they had rather short lives - needing to be replaced every few years (which conventional compressors did not). However I can't say how those factory scroll compressors compare to the ones you are considering, perhaps there's a major difference.

I was trying to come from an evidence based point of view rather than guessing or hoping for the best by identifying the original compressors refrigerant discharge capacity as a base line.

Most modern small engine capacity cars these days come with scroll a/c compressors so I’m assuming this is because the scroll compressor is more efficient than a piston type compressor. Mind you nothing these days is built to last, quite the opposite infact but that’s another subject.

I’m starting to realise that by even coming from a “evidence based” approach I’m not going to be able to reconcile the differences between OE, modern scroll & 12v electric (non idle) compressors.
I would love to avoid the convoluted 3 belt design of the crank driven compressor in the X1/9 but not at the cost of a completely ineffectual 12v driven compressor.
Unfortunately I know no one who has this in a car to demonstrate to me how effective the 12v compressors are in real life only what I’ve seen online and that’s no guarantee what so ever as you don’t know their motivations.

 

[Stuartc]

This document shows the performance of various Sanden compressors. The SD5H14 would be the one closest to the SD508 in capacity (both listed as 138 cc / revolution, both being 5 cylinder units). The graph shows about 5 kW of cooling capacity at 2000 RPM (reasonable cruising speed). Looking at the X1/9 pulley sizes, compressor speed and engine speed are about the same (corroborated by the Sanden spec of max allowable speed of 6000 RPM continuous / 7000 RPM peak). The 12V Rencool unit has less than half that (2.15 kW) at peak RPM. The SD508 may be generously sized for the X1/9, but having less than half that capacity in a hot climate would worry me.

The other problem is power draw. The Rencool at 3000 RPM (and only 1.38 kW of cooling capacity) draws 0.74 kW of electrical power. That comes out to 53 Amp at 14V. The Bosch alternator rated 65 Amp produces only about 45 A at 2000 RPM, so unless you get a much larger alternator, you don't have enough electrical power to run the 12V Rencool even at 1.38 kW of cooling capacity.

I have looked somewhat casually at alternative A/C compressors. Sanden SD5Hxx and SD7Hxx are available in configurations that would make them drop-in replacements for the SD508 (at least for mechanical mounting). I have not seen any scroll compressors with SD508 style mounting ears, so a tensioner bearing setup would be needed.

It looks to me like anything other that dropping in an SD7Hxx or SD5Hxx would increase the effort required dramatically without providing a commensurate improvement in performance.

Incidentally, I know someone who refurbished his X1/9 A/C system much like @LarryC did in the threads I referenced earlier (larger condenser, new wobble plate compressor, new JLR receiver drier, R134a) and the system works very well.

Don’t disagree with anything you’ve outlined, the only thing and I’m not sure if there’s anyway to reconcile is comparing the crank driven and electrical driven compressors ie non idle v variable rpm. Being completely different states of operation can a comparison be drawn. Plenty of vids out there saying the electric driven compressors work! I’m still sceptical though!
My plan is to fit the largest condenser possible but I’m no where near that stage atm and same reason for cooling fans energise immediately A/C is active albeit on low speed.
Current 55A alternator will be swapped out for Bosch 150A alternator along with 2awg battery to starter wiring and upgraded alternator to starter wiring.
I’m really wanting to avoid the convoluted 3 belt setup of the mechanical driven compressor but not to the point of having inefficient A/C.
If I do use a crank driven compressor it will be more likely be the 80cc Scroll compressor which will require a completely new mount anyhow and I will make it so that the compressor swings in/out to adjust belt tension.

 

[kmead]

I was trying to come from an evidence based point of view rather than guessing or hoping for the best by identifying the original compressors refrigerant discharge capacity as a base line.

Most modern small engine capacity cars these days come with scroll a/c compressors so I’m assuming this is because the scroll compressor is more efficient than a piston type compressor. Mind you nothing these days is built to last, quite the opposite infact but that’s another subject.

I’m starting to realise that by even coming from a “evidence based” approach I’m not going to be able to reconcile the differences between OE, modern scroll & 12v electric (non idle) compressors.
I would love to avoid the convoluted 3 belt design of the crank driven compressor in the X1/9 but not at the cost of a completely ineffectual 12v driven compressor.
Unfortunately I know no one who has this in a car to demonstrate to me how effective the 12v compressors are in real life only what I’ve seen online and that’s no guarantee what so ever as you don’t know their motivations.

Hussien changed his to a serpentine belt with tensioner to get away from the multi belt system. My recollection is he used a 5 rib set up to work in the space available. It is in his earlier modification threads, I will see if I can cast about for it.

I believe it starts about here:

Serpentine Belt / Pulley Conversion?

My serpentine belts are fourteen years and counting on my Golf, 10 years and counting on my Sienna. I must like living on the edge... But then I am rarely far from home with these cars.

xwebforums.com

 

[Buckroe]

True. As a result, I would not recommend using any of the original hoses as they hold a lot of old refrigerant in the material lining the inside. Not to mention they likely leak. Besides, the original lines had all of those horrible sensors and such that you will want to eliminate, and therefore a lot of extra fittings you won't need. Naturally you also don't want to reuse the old receiver/dryer (filter).

Basically I replaced everything with new universal components; compressor, condenser, receiver/dryer, expansion valve, hoses, etc. The only factory item left in the entire system is the evaporator due to its unusual size/shape. New ones can be made but are quite costly. Mine was in good condition so I thoroughly flushed it and refit it with new seals (of proper material for the new refrigerant).

This is why I stated earlier that it really isn't that difficult to add AC to a non-AC car. Basically you will be using all new universal components that are readily available and affordable. The only Fiat components that will make the installation easier are the mounting brackets for the compressor and the AC style heater box (with evap). You can either swap in the dash controls for the AC heater box or do what I did and convert them to manual controls (I hate vacuum controls). The couple of factory parts needed should be easy to find due to lots of owners with AC wanting to remove it.

Dr. Jeff, any thoughts on who would be able to do a non-AC to AC conversion? Could a regular AC shop handle it? Any ball park on the cost? I’m in Miami and as much as I love this car, six months of the year it’s just too hot.

 

[Dr.Jeff]

I was trying to come from an evidence based point of view rather than guessing or hoping for the best by identifying the original compressors refrigerant discharge capacity as a base line.

Most modern small engine capacity cars these days come with scroll a/c compressors so I’m assuming this is because the scroll compressor is more efficient than a piston type compressor. Mind you nothing these days is built to last, quite the opposite infact but that’s another subject.

I’m starting to realise that by even coming from a “evidence based” approach I’m not going to be able to reconcile the differences between OE, modern scroll & 12v electric (non idle) compressors.
I would love to avoid the convoluted 3 belt design of the crank driven compressor in the X1/9 but not at the cost of a completely ineffectual 12v driven compressor.
Unfortunately I know no one who has this in a car to demonstrate to me how effective the 12v compressors are in real life only what I’ve seen online and that’s no guarantee what so ever as you don’t know their motivations.

I fully appreciate your approach to using the stock system as a basis for determining the capacity needed. However most often car makers decide such things more on cost than actual engineering calculations....especially back then, and even more particularly for makers of cheap "throw-away" cars like Fiat. So I wouldn't necessarily consider that data too strictly.

My understanding is the scroll type compressor is more efficient in terms of engine load, not in terms of interior cabin cooling capability. In fact it is a trade off, giving up cooling effectiveness in favor of things like emissions, fuel economy, etc. Those are far more critical for the manufacturers these days than comfort or longevity. But that's only based on the opinions I've heard from some AC experts I've talked to.

I really can't offer any useful info about electric compressors. I know they have been around in one form or another for many decades. Mostly for use in things like large agricultural equipment, commercial vehicles, and such. Looking at many of those earlier systems they appear to be nothing more than a conventional compressor with a electric motor added in place of the drive pulley. However I'm sure as electric cars become more mainstream, electric compressors will develop significantly better. Maybe it's still too soon in that evolution process? No idea. But as @ng_randolph said, they require a lot of electrical supply. Have you compared the load a 150A alternator places on the engine compared to a conventional compressor?

I can appreciate the desire to eliminate the multi pulley V-belt arrangement on the X. Actually there's two or three different arrangements for AC equipped X's. Some are worse than others; you might see if one of the other layouts suits you more. Maybe consider redesigning the drive system rather than change the compressor style? As @kmead said, going to a ribbed ("serpentine") belt drive arrangement with the existing components is another option. The Sanden 508 is readily available with either style pulley on the clutch. And there's a rib belt system available for non-AC SOHC's that might be a starting point.