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521 a/c questions

'70 521 L16

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I finally got my truck running! The next thing I want to take on is getting some cold air blowing inside since it's been 100+ all week. I already have most of the parts I'll need, but I can't figure out how I should mount the condenser. I'd really like to avoid chopping up the stuff between the grill and radiator, but I don't see how else it could be done. Does anyone have oics? Ideas?

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Depending on age, this may sound foreign...


On your door, there are 2 levers.

One opens the door.

The other is your window crank.


Counter-clockwise will "roll" your window down.

Clockwise will give the opposite results.


AC on an already low-powered car just seems like too much work for not enough reward.

If you were pushing a KA or something then it seems more doable.

But not with an L. Too much drain.

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its worth it to me. the truck is just a get around kind of thing. i dont mind losing a little power if it means an escape from this heat, and if i dont like it i can take it back off. i think the under dash vent units look really nice too. so does anyone have any actual info? im just wondering how the factory option ones were installed.

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There were no factory options installed. There may have a few dealer installed options done.

You will be on your own putting A/C on a 521.
In this picture, you can see two bosses on the side of the L-16 engine block straight down from #1 exhaust port, and another two bosses below #2 intake port. These bosses have an M8x1.25 tapped hole in them, and were used for a bracket that held the air pump. That is a common place to put the A/C compressor, you will probably have to fabricate something.

This picture is of a 521 without the dashboard, or the air box, that is above the heater.
This would be an ideal location for the evaporator of the A/C system, but it would have to be pretty small.

The last major piece of the puzzle would be the location of the condenser. They are usually put in front of the radiator. This may cause some overheating issues with the engine. Usually when cars are built with A/C, the cooling system capacity is increased to account for this.

I think the best option for the compressor would be to find as early of a 620 truck as possible, with A/C. 620 trucks started out with the L-16, got the L-18 for a year, and then had the L-20-B engine. I think the bosses on the engine block were retained on the L-18 engines, I am not sure about the L-20-B engines. Grab all the other A/C parts you can get, it you find an A/C 620. You may have to use some parts from other cars to get it to work.

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The original condenser went between the radiator and the grill. There is a huge open space in there. Only way to reach it is by removing the radiator.



Condenser looks like this, relatively small:



The under the dash unit was seperate from the heater/blower motor. The A/C had its own blower motor and blew through a vent system that bolted to the underside of the dash. The vents did not do the defrost (that is for the heater/blower), they only blew directly on you.The control knobs were formed into this under dash unit. The entire thing was hollow like one big vent. Mine was broken in half but you get the idea.


Here are the controls on the broken under dash vent system. This is the drivers side, thus the hump in the vent for the steering column:



The blower motor on the A/C unit is substantially larger, actually it's two fans instead of one fan like your heater, and moves a shit ton more air.


Here is the entire system, minus the compressor. There is the condenser, dryer, vent system, and blower motor/under the dash condenser thing that does the actual cooling:



It tucked up nicely under the dash so there is enough room for feet. The compressor is a bigass thing. Probably wouldn't want to use an old compressor anyway. Modern compressors shouldn't sap TOO MUCH power but like everyone else said... you barely have any to begin with.



Bolted on the dizzy side of the motor, thus all the bolt holes in the side of the block which also make very good mounts when on the engine stand, especially for L6's!



Speaking of L6's, I am snabbing a friends A/C system from his 280z for the truck. Compressor and its mounting brackets should go right onto our L4's and it is substantially smaller than that thing above. May have to fiddle with spacing to get the belt to work properly. 280's had a three row pulley, I'm currently running a two row on the truck and there isn't any more room for a third row, the frame rail gets in the way.


Making brackets to mount the under the dash unit will be easy. The hard part is making a vent system. I have to look at the vent outlets on the unit but if it is similar to our heater boxes, where it has two outlets for hoses to go right on, that will be easy. If not, I was thinking about forming a fiberglass thing that bolts onto the outlet of some sort and makes it so that 2" ventilation hose can fit onto it.


Because the cabs are small, I'm not worried about where exactly the air is blowing, the entire cab should cool quickly. My radio is in the glove box and I have a center console running between two MG seats. This means I have a rectangular hole in the center of my dash where the original radio or whatever use to be. I plan on putting either one large vent or two slim vents in that hole, fed by one 2" hose. With two slim vents, the driver and passenger can have their own but again lets get real, I don't have anyone in the car with me over summer anyway so one large vent that I can adjust to blow on me is sufficient. The other 2" hose could go to the center console with a vent blowing towards the legs, again either on both driver and passenger or just driver.


Or, ditch the center console vent thing and just drill a hole in the passenger side of the dash, you know like on the drivers side where the ignition switch is, in that spot but on passenger side, and add a vent there. Example photo when I was working... just to the right of the glove box is the location I am speaking of. You can actually see the two holes in the firewall through the glove box where the A/C hoses went through.



This setup would be similar to the stock/dealership setup in that your A/C will not defrost and the vent system is completely separate from the heater vent system.



What I am curious about is what did they do to the throttle, if anything, when the compressor kicked on? Was the idle just set higher than usual, at all times or was there a switch that bumped it up?

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Not to sound presumptuous, but do you even know what refrigerant you're going to use? You'll pay out the nose for R12 on an old system like that...that is, if you can even find it.

Convert it. Since either route OP/myself goes we will have to practically make our own A/C system, this means we will need new hoses which means while I'm at it just change the O-Rings and the dryer. Don't know if the compressor has to be changed but I wouldn't mind that as well to go to a modern compressor that doesn't sap as much power.


There is always Vintage Air or any other vintage A/C company that sells kits with modern equipment. Usually $1100 though! Recently did one of those on a TR6 and it worked out well.

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