Air conditioning retrofit

Jeff Stich

True Classic
Belts, etc.

Since I am using an after market compressor, is there any reason why it needs to go below the alternator as in the stock configuration?
Probably the main reason Fiat arranged the compressor, alternator & water pump that way was due to the drive forces needed to turn the compressor pulley. With the compressor driven straight off the crank pulley, it saves wear on the alternator &/or water pump bearings & housings, since there is no increased load on them compared to being in a non-A/C set-up (ie: they are both simply being driven by a belt). If the same belt/pulley configuration is used, if the alternator was mounted in the "old" stock location & the compressor was mounted up top, then the alternator (pulley) would have to drive the compressor & the water pump (& the air pump on early cars). That's a bit of a load for those little alternator bearings...

I have a stock '81 with the single V-belt and a Delco alternator that works just fine. If I can figure out a way to mount the compressor to the water pump, couldn't I just run a second belt from a double pulley on the crankshaft to it or a belt from a double pulley water pump to it. Then I would only need two V-belts instead of the three in the stock configuration that looks like a nightmare.
Looking at the diagrams below, if you were to simply swap the places of the compressor & alternator (assuming things fit spacially), & retain the same general belt & pulley configuration (ie: crank driving compressor directly using a longer crank-to-compressor belt, with compressor driving alternator & water pump), that might work?

The main issues then are most likely how to hang the compressor up there, & how to tension the belt?

Speaking of the water pump, am I correct in assuming that the housing for an AC water pump is different than a non-AC? I know the impellor and double pulley is different.
Yes, the A/C water pump is indeed different (see my reply to Tony's post).


Tony Natoli
OK... I stand somewhat corrected and I thought...

about the bolt-on clutches a bit later as well, but they were outside my personal experience.

I purchased a 50 dollar water pump back in 1997 or so that had a pressed on DUAL pulley that I feared would be in the way... So I had the old single-groove pulley pressed off the old pump and pressed onto the new one. I had always assumed that the dual pulley pump was for the A/C equipped cars. I was totally unaware of the material changes... and stress issues. I figured the belt tension and slippage would be the main issue as it generally was on the many American cars I have had experience with.

In any case... installing the new aftermarket system is gonna have its challenges... but I am sure it will be well worth it in the end.


True Classic
Now it's clear

Thanks, Jeff for the detailed pics of the water pump. All of the other pics I would find were just looking straight at it like your first picture. I could never make out the mounting tube for the alternator before, but yours shows it clearly. The non-AC alternator set-up mounts to a cast iron bracket on the block, but with AC there is a different bracket that the compressor connects to in its place. I couldn't figure out how the alternator was mounted but I assumed it had to be connected somehow to the water pump. That is probably why Fiat made it out of cast iron so it could take the stress of having the alternator hanging off of it. I have an upper alternator bracket for an AC car that bolts to the cam box but it would not fit around the non-AC water pump and now I know why.

In regards to your post about the belts, I think what I will do is to mount the compressor and alternator in the stock positions since the brackets already exist but instead of using three belts like the typical FI AC set-up, I will use a two belt set-up like the one with the air pump, but of course no air pump.

I was looking at LarryC's thread on his AC upgrades and clicked on one of his photos that took me to his Photobucket folder and found this diagram the he did for how his is set-up.

He only used two belts. His is carbureted and he is using a Delco alternator with some custom fabricated brackets so I don't see why that shouldn't work fine with my FI engine. Seems a lot simpler than the three. The aftermarket compressors come with a double V-belt pulley so I can use the inner pulley and run it to my single crankshaft pulley, then use the outer pulley on the compressor to the outer pulley on the water pump. I just need to play with the alignment of the alternator to get the pulley to line up. I will be using a Delco one as well so some customization of brackets will be needed anyway.
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True Classic
Hurricane trial fitting

I got a little side tracked on playing with the mounting positions of the compressor and alternator but more on that later. I first had to see if the Hurricane unit would fit in the X. The two things that limit the width are the fuse panel tray on the right and your foot on the accelerator pedal on the left. The blower housing for the Hurricane is mounted on the left side and tends to want to hang over the space available for your right foot. I played with the try-in case and found that it will fit.

At first I had it more toward the firewall and up high, to allow foot space, but then the defrost openings are too high up under the dash board and pretty much useless. I debated just sealing them off and using two of the four outlets that would normally go to the dash vents and send them to the defrost outlet. Since I had decided not to tie in the side dash vents, I could just close off the center vents to defrost, like we have to do anyway with the stock set-up. That seemed like a shame since the Hurricane comes with an electronic motor control to select defrost or vent. I eventually decided to see if moving the unit further toward the rear of the car and lower would allow me to use the defrost outlets. This was an improvement, but now the blower housing was kind of getting in the way of my right foot. I could bring it further rearward but I would need to modify the passenger side pad of the console some and cut a little sheet metal from the console-dash support.

This shows where I cut.

Here is the unit in place after the cut and with the fuse panel tray in.

Here is some crude modification of the console pad. The console in this car was pretty sun baked and cracked so I had no qualms about cutting it up. I will be more careful with the good one.

This is a view looking at it from the driver's seat. You can see the vertical two defrost outlets through the stock opening to the defrost vent. I will have to fabricate a connection from those to the stock vent out of something.

This the other side showing the clearance to the accelerator pedal. I had the unit propped up on bubble wrap.

This next picture shows the console in place and you can see the four vent outlets through the center console vent opening. I will also need to fabricate a connection from the two center ones to the vents. I plan to run hoses from the two outside ones and aim them with small aftermarket vents down into the footwells to provide additional cooling/heat.

The other advantage to moving the unit towards the rear of the car is that it opens up a lot of space between the unit and the front firewall for the connections. Originally, I thought the side connections would be best, but it turns out that the ones coming off the upper back side should work best to connect the AC and heater lines. The other nice thing is that the drain pipe from the unit ended up almost right above the stock opening for it. Here's a picture of the space behind the unit and then one of the drain pipe.

This seemed to work out pretty well and so I bit the bullet and ordered the real unit from Old Air Products. I ordered the same compressor that LarryC recommended from Nostalgic Air, as well as their hose set, which includes a compact drier which should fit nicely in the stock location and has a fitting for a pressure switch. I went with the trinary switch so it will run the condenser fan.

More later as I have time.
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Tony Natoli
WOWOWOW!!! This is great stuff!!!

Most units I have seen have the fan motor on the right side... and this might have been a better fit if so.

But ya gotta do with what ya have here...

Secondly... I would find a way to include both side vents and not worry about fresh air if it can't be done through the unit. My installation completely eliminated fresh air though the evap unit. All is recirculated for heat and A/C. If you want fresh air, ya gotta roll down the window.

The side vents will really aid in the cooling... along with a center vent or vents... and heating usually flows straight out of the bottom... defroster should be OK from what I see in the clearances you photographed.

With the 4 outlets, (judging from my chair here...) I would think you would use the two center outlets to vent straight out the radio hole, and then run the two outer outlets to the left and right "fresh air vents".

The radio head or stereo itself will need to be fitted into the center console... which needs to be modified anyway.

Great work Rodger... keep it up!


True Classic

The other units that I looked at do have the blower on the right side, but they are all too wide to fit in the X without taking up half the passenger footwell and interfering with the fuse panel tray.

I have gone back and forth on hooking in the side vents. It would be easier if I could acquire the vents from an AC equipped dash, but they are riveted to the dash, whereas the ones in a non-AC car are bolted to the body. I have lived with my '79 non-AC for 35 years and I really like the fresh air coming through the vents with the top off. There are those hot days though when some AC would be nice plus I will be moving to warmer climates when I retire in a few years so that is why I embarked on this project in the first place.

I would like to keep the fresh air option so I don't have to run the air conditioner just to get some circulation in the car if I have the top on. As far as the center vents go, they will go right to the stock vent openings so there is no need to come through the radio opening.
Haaaa, thats exactly the box I was lookin at for adding the A/C to moms 74, im watching with eager eyes! I have the early dash though obviously. And limited vents, only 2 for ur face, I may try to figure out how to run insulated tubing to the other vents on the edges of the dash as they are outside air only vents.

When I did mine i was gonna try to source some stock a/c bracketry and run the new style compressor.

So the box fits ok? your thoughts on where the lines come out? There were options on where to have the lines exit and weather you want electronic or cable controls, what did you opt for?


Tony Natoli
I understand completely Rodger... BUT...

With the HUGE volume of air that most of these aftermarket systems provide... they just can't keep the cabin comfortable with just the center vents! The restriction of the vent just as to their size, and the heat gain regardless will be a problem.

I find that in my Vette that the side vents, especially focused higher for my face and upper body, really makes a difference.

AND... YES... I do miss the cool air vents at times... but I usually drive with the top off anyway with the X... and in the Vette, I roll down the PASSENGER side window so my "do" doesn't get ruffled...

I hope I have persuaded you... In either case though, changing your mind later will be about an equal task. HTH!


Tony Natoli
I haveta agree with Kevin and Tyrone here...

Insulation is a real plus both for sound, a simulated rigidity, and does indeed keep much of the engine heat out of the car. Not perfect, but a PLUS even with the top off.

Noooo, I haven't done my X yet, but have done my Vette. So I do have some personal experience here.

As for insulated duct work... well, that's going a bit far. There was some for homes made of stiffened fiberglass and that's a good idea and less expensive overall, but I don't think they have smaller, flexible sizes that you would need in this car. Plastic corrugated ducts are the norm and work very well, AFAIK.
I don't think I wold bother with insulated ducting. Stock in late model cars is just corrugated plastic ducting.
True but i dont remember how much room is between the inside of teh car and those side vents....the tube that connect them to the cowl is only a few inches long, may be possible to sneak the tube inside the car, but may be easier to run them out through say the fresh air door or something to the openings. Again, its been a while since ive really done anything to the car let alone looked in there..the tear down is next years project, either way im stoked to see how this all works out for you


True Classic
Just a though that popped into my head. The rubber insulating jackets that they make for home Air conditioner freon lines is probably about the right size to use to for the X 1/9 side air ducts. I was just fixing my home AC that was leaking water and found that some of the rubber jacket was ripped. A little duct tape fixed it.


Bjorn H
True but i dont remember how much room is between the inside of teh car and those side vents....the tube that connect them to the cowl is only a few inches long, may be possible to sneak the tube inside the car,
In my '85 with factory A/C the side vents are fed with what looks like 60 mm corrugated ducts running inside the dash up against the firewall. The fresh air ports in the left / right cowl are blocked off.
In my '85 with factory A/C the side vents are fed with what looks like 60 mm corrugated ducts running inside the dash up against the firewall. The fresh air ports in the left / right cowl are blocked off.
Good to know, but the dash is different from 74 to 85, is the placement of the side vents in terms of distance to the firewall any different?


True Classic

When I did mine i was gonna try to source some stock a/c bracketry and run the new style compressor.

So the box fits ok? your thoughts on where the lines come out? There were options on where to have the lines exit and weather you want electronic or cable controls, what did you opt for?
I decided to use as much of the stock bracketry as I could. I got the compressor bracket that mounts on the block in place of the alternator bracket plus the mounting plates that hold the compressor. I also had to change the water pump to an AC version as the stock water pump will not allow the compressor brackets to fit. The other bit is the alternator. I have run a Delco-Remy alternator on my '79 as do many others on the forum. I wanted to stay with that on this conversion and picked up an S12 78 amp type at my local Car Quest and will be working on fitting that once I get the compressor and start playing with the mounting. The stock alternator bottom mount attaches to the water pump and the top adjustment mount to a bracket that comes off the cambox. I will post pictures once I have the compressor and have figured out the alternator mount.

I got all of the Fiat parts from MWB. I am not familiar with the 1300 block to know if it has all of the same holes to use the brackets that I have. I am pretty sure from pictures that I have seen that the water pump on the '74 is unique so not sure how it would go together.

As far as your question about the exit location for the AC and heater lines, you are right, there are three choices: out the right side, out the upper back, or out the lower back. The last two are to go through the firewall of a front engine car. I first thought I would pick the side exit lines, but I am glad I got the trial case to play with first. Once I got it positioned where I wanted it, it turned out that there was plenty of room between the back of the unit and the firewall to the frunk to bring the connections up behind and still be able to get in and connect them. If they came out the side, it would create a problems with the clearance to the fuse box. I ordered the unit with the connections on the upper back so hopefully I picked right.
Only reason I said insulated duct work is because I didnt know if there was room behind the dash for ductwork for the vents on the ends of the dash, thought they may have to be run into the cowl...but after taking a peek last night, there is definatly room in there for duct work behind the cluster and room to remove the short hoses for the vents and plug em off. I have the fuse box under the dash by the clutch pedal and the 1300 will be coming out for a 1500. SO far as I can tell 1300 A/C parts are unobtanium at least in the states as the 1300 cars were dealer installed A/C, not factory A/C...ive seen how the setup is and it nutso...the compressor faces the other direction away from the pullys, and the waterpump shaft is double long with a pully on both sides. Besides, eh lack of torque from the 1300 is no bueno for A/C haha. Was that case you bought a loaner for fiting? Or was basically disposable $$ as you needed to be sure it fit. Cause I may wanna borrow it from you haha


True Classic
Trial box

It would be great if Old Air had a loaner, but I had to buy it. It was only $95 so I figured that was a small investment to play with it before I committed to acquiring all of the parts to do it for real. I am glad I did because that is how I decided on the location for the connections. I will not need it once I get the real system fitted so you can certainly borrow it (or better yet, buy it from me:)).

I ordered the version with the electronic slide controls. Ideally, I would like to see if I can somehow mount them so that I can use the stock lever faceplate to keep the stock look. We'll see.


True Classic
Added the compressor and Delco alternator

While waiting for the Hurricane unit to arrive, I decided to work on the installation of the compressor and alternator. I ordered the same Sanden type compressor from Nostalgic Air that LarryC used in his stock AC upgrade. It comes with a double pulley unlike the stock FI unit that has a single. I also ordered the stock AC water pump and the double pulley that goes with it. I also ordered the stock AC compressor mounting bracket that attaches to the block in place of the alternator bracket as well as the compressor mounting plates and bolts to connect the compressor to the bracket. I also got the stock alternator upper bracket for an AC FI car that connects to the cam box since the non-AC one is attached to the original water pump. I got the double pulley and shims that replaces the single pulley on the crankshaft, but I was able to work out a solution using only two V-belts instead of the three that the stock system uses so I will be returning that. Thanks to Matt at MWB for providing all of the used items and a new water pump.

I got the idea for the two belt set-up from LarryC, since his ’79 stock AC system only comes with a two belt arrangement as well as from Dennisrh, who posted on his thread about moving his AC system from his totaled Bertone to a non-AC one and only used two belts. Larry’s ’79 is carbureted so that uses a different water pump than the FI AC cars. From what I can tell, it positions the water pump pulley in a different plane than the FI cars, plus the compressor mounting plates and the upper alternator bracket are different as well in a carbureted car.
Here is the compressor bracket and water pump mounted, then the compressor mounting plates.

On top of this, I wanted to fit a Delco-Remy 12SI 78 amp alternator instead of the Bosch one. I saw the recent thread from old mech ( who did this on an AC FI car by using a hacksaw to modify the bottom mount on the alternator and then fabricated a custom upper adjusting bracket from ½” steel. I don’t weld, but I can cut, grind and drill, however, the thought of trying to hacksaw out a bracket from ½” steel did not sound like fun, plus I did not want to hack up my alternator case. If you ever need a new one, you have to return the exact same one to avoid the core charge. Granted it is not much, but still…. As Tony stated, if you get stuck and need a new one, it is much simpler to just bolt in the replacement. I wanted to figure out a way to mount it intact. Plus, I only wanted to use two belts so I was not tied to trying to make it fit the stock mount.

I initially tried to do this with the engine in the car, but that was not going well with the limited access. The engine was going to come out anyway for the car to go to the body shop in a few months so I had to detour for a few days to drop the engine. Much better! Of course, as I played with the arrangement, I would hoist the engine back into the car to make sure the alternator position cleared the sheet metal. I was frankly amazed that the mod that old mech did with the custom upper bracket actually fit in the car without hitting the top alternator mount on the rear of the engine compartment. Since the Delco alternator has the mounts at 12 and 6 o’clock, when you mount the alternator to the water pump as the stock is, it tilts the alternator rearward and positions the top mount towards the rear of the car, hence the need for the long curved custom bracket.

My first step was to mount the AC compressor with all of the stock brackets. As it turns out, the outer pulley of the new compressor lines up perfectly with the stock single crank pulley. Of course, it would also line up with the inside pulley of the double crank pulley so this compressor would be a bolt in replacement for the stock one. I wanted to run the second belt from the inside pulley of the compressor to the water pump and alternator like Larry’s ‘79, but the water pump pulley as mounted in a FI car has the outer pulley lined up with the outer crank pulley and the inner pulley lines up with the stock alternator pulley. I found that if I turned the pulley around and mounted it inside out, it moves the whole pulley inboard so that the outer pulley groove lines up with the crank pulley and outside compressor pulley groove, and the inside pulley groove lines up with the inside compressor pulley. There is a seat machined on both sides of the water pump pulley that fits perfectly over the water pump impeller mounting plate either way so Fiat must have designed it like that for a reason. From what I can surmise, this is how it is mounted on the carbureted AC cars. The clearance between the inner edge of the pulley and the snail engine mount is very small, but there. You have to take off the pulley to put the belt on. This is actually much easier with the pulley inside out because there is much more clearance to the passenger side of the engine compartment.

The other thing I found is that the timing bracket on the non-AC cars is different than the AC version. It has a slot cut out of it to clear the belt going to the compressor, plus it sticks out further to line up with the timing mark on the outer crank pulley. Dennis’s install ran the belt from the crank to the compressor and the water pump and by doing that, it clears the timing bracket. I PM’d Dennis to see how his two belt set up has been working and he said fine for the past year and a half. The only issue is he has to keep that belt pretty tight to avoid squealing from the belt. I surmise that this is because there is only about 90 degrees of wrap of the belt on the water pump so that has to drive both the pump and the alternator without slipping. I was planning on running one belt from the crankshaft pulley to the compressor and the second from the compressor to the water pump and the alternator so I had to cut a slot out of the timing bracket to allow clearance for the belt.

I decided to mount the bottom foot of the alternator to one of the upper mounting points on the compressor, which is how Larry’s X is. For the pulley side of the mount, I modified a bracket that was part of a conversion bracket set that I found on eBay for converting from a generator to a Delco alternator. I originally thought I might be able to use that to mount the alternator to the stock water pump mount, but it took up too much room. I took one of the pieces of that set and modified it with my trusty hacksaw and drill. One could make the same thing out of a piece of ¼” steel, but since it was mostly the right size and I had it, that’s what I did. As it turns out, when I mounted the alternator to the compressor like that, the fronts of the cases line up and the pulley of the alternator is perfectly aligned with the inside pulley grooves of the water pump and compressor. The gods were smiling on me that day.

When I first bought the 12SI alternator at auto parts store, I did not know which one to get and the gals behind the desk had no idea what a 12SI or 10SI was. I have read the thread about using a 10SI from a ’78 350 Camaro, but I wanted the 12SI due to the better cooling and electronics. The gals were very indulgent and after a couple of attempts, I got what I wanted by specifying a 1986 V-8. I wasn’t sure how I wanted the clocking of the outputs, but the one I got had the outputs at 9 o’clock. Once I started playing with it, I realized that would put the outputs right next to the exhaust manifold. At first, I thought I would have to go back and get one with them at 12 or 3 o’clock, but as I looked at the alternator, it looked pretty symmetrical to me. I took out the four bolts holding the case halves together and apart it came. It turns out, that you can turn the back to any of the four positions you want and then it bolts right back together. If you take it apart as I did, the brushes pop out, so you have to put those back in to put it together. There is a small access hole in the back to insert a small screwdriver to hold the brushes in place while you put it back together. For future reference, just remove the bolts, and twist the two halves to how you want it clocked.

It seemed like using just one bracket on the front would put a lot of torque on the bolt and mount when the belt was tightened so I wanted to have a second bracket at the rear of the bottom alternator foot. The stock alternator to water pump mounting was not far away and very substantial so I looked at that as a mounting point. I needed a curved bracket to clear the alternator case and leave room to pivot the alternator when changing the belt. I was looking at the new stock alternator bracket that I had acquired and noted that the curved portion end was the perfect curve I was looking for. I wouldn’t be using either the bottom bracket hole or the hole with the braised on nut for tightening the upper adjusting mount point on the stock alternator, so all I needed of it was the part with the hoisting ring and a place to drill a hole for a new upper adjusting arm.

Here are pictures the bracket that I made for the pulley end of the alternator as well as of the stock bracket next to the one I cut up to make two brackets for my needs. The lower curved piece fits nicely between the water pump mounting point and the lower alternator bolt. I cut down a ½” spacer to correct for the offset between the water pump and the alternator foot. I could have used a bunch of washers, but I this looks cleaner to me. For the upper adjustment, I found a nice 2.5” stainless adjustable Heim joint rod on eBay for $39.95. I drilled a hole in the upper bracket and mounted it so that it was close to parallel with the V-belt. I used an M10x100 mm bolt for the bottom alternator mount and an M10x70 mm for the mount to the water pump.

Now it was off to the auto parts store to get some V-belts. After some trial and error, I found two that worked well. The outer crank-compressor belt is a 10x840 mm and the compressor-WP-alternator belt is a 10x802 mm. Here it all is outside and inside the car. I think it should work well, but it will be next summer some time before (hopefully), it all gets put back together and actually fire it up. If anyone sees something I have overlooked, please chime in. I could not have done this without all of the ideas from Forum members.

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Wow, looks good im impressed...haha the dash and interior was the only part i was really concerned about, I had no idea there were so many options for bracketry and waterpumps on the block. So FI and carb brackets are different, and waterpumps too? Sorry im tired and curious, bad combo :p