How to install A/C in a 1st Gen Pickup/4Runner (1 Viewer)

yotadude520

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Here it is! The much anticipated (much dreaded for me) writeup of how to install AC into a 1st generation 4Runner or pickup.

I’m going to warn that this is going to be a very long, extensive, boring, picture heavy writeup where I’m going to compile all the research I have done and the entire process from beginning to end.

I’m going to break down this writeup into 5 parts which are:

-Getting started and finding the parts

-Evaporator

-Compressor

-Condenser/Drier

-Hooking it all up


Getting started

So you want to add AC to your 1st gen 4Runner/Pickup? It’s definitely doable and not too troublesome once you have everything you need. The best way to get all the parts you need is to find a donor vehicle – which is easier said than done. If you can – great! You’re ready to go. If not, these are the parts you’re going to have to hunt down.

-Evaporator box
-Evaporator
-A/C Wiring harness
-A/C compressor bracket & idler
-A/C lines (including those on the condenser)
-Condenser
-A/C switch for in cab
-Drier
-Thermal expansion valve
-Low pressure switch
-Thermistor
-A/C Belt
-Idle up solenoid & VSV
-O-Rings & Pag Oil

You do have the option to buy many of the main components new, but at the very least you need to buy a new drier & expansion valve before you do your install. I would recommend ponying up the coin to get a new compressor as well since original ones tend to leak from time. Unfortunately finding a lot of the A/C lines can be a pain so if you can find a donor vehicle, all the better.

Evaporator

UPDATE: Do NOT use the Four Seasons Expansion valve (Part #38616). Buy it so you get the lifetime warranty on the compressor but install the Denso one as mentioned in the post below. My brand new Four Seasons Expansion Valve failed right out of the box, blowing an A/C line & requiring it be replaced.


I went ahead and bought all new parts for my truck where I could. I probably didn’t need to replace the evaporator, but I decided that I don’t want to mess with this system for a long time.

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Inside the evaporator box is the evaporator, expansion valve, low pressure switch & thermistor. There is also a small A/C line that goes off the expansion valve and to the outside of the box which you need to have.

The box can be taken apart by removing the 4 screws and clamps on the sides of it. The box will split in half where you will see the evaporator and all it’s components. Compare the old evaporator with your new one to make sure they are the same.

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Unplug the low pressure switch & remove the thermistor.

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Disconnect the metal hard line from the expansion valve. With the line disconnected you can easily remove the pressure switch.

Remove the foam around the larger hard line and remove the clip that holds the probe off of the old expansion valve.

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Install the new expansion valve onto the new evaporator and attach the probe to the large hardline of the evaporator.

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I also had an adapter that came with the expansion valve to fit onto the small hard line that holds the pressure switch which was also replaced. (You can see it above). Clean the inside of the plastic evaporator box and remove the amplifier on top of the box and check to make sure there is nothing wrong with it.

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I put new foam on the top and the bottom of the evaporator and also re-foamed the hard line with the expansion valve probe. From here you just need to put it back together and get it ready to install the truck.

Inside the truck there is a small piece of duct work that connects the blower motor and the heater core. The new evaporator will replace that piece and sit inbetween the two.

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To get to this ductwork the glovebox & glovebox support needs to be removed.


Remove the ductwork with 4 screws. It should look like this when out of the truck.

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My truck used to have AC but was removed with the idea of an on board air system in it’s place. If your truck never had A/C you’re going to need to drill three holes – two for the evaporator & one for the condensate drain. There are factory dimples in all locations so you can center your hole drill. From the installation manual attached the hole should all be 32mm (1 ¼”).


Install the evaporator through your new holes & attach the condensate drain. Install grommets to keep everything sealed. I had to re-route all of the mechanical gauges since they were installed through the original evaporator hole. Unless this has been done on your truck too, then you can skip this step.


A huge concern I had with the entire A/C conversion was wiring it all up. All Toyotas came with the wiring to install factory A/C, but you need a smaller A/C harness to plug into your main harness. It looks like this:

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Toyota changed the connector that plugs into the main harness in 1987. From 1984-1986 the connector was a 4 pin. From 1987 (and later I assume?) the connector changed to a 5 pin. Make sure you get the correct one for your truck. The parts truck all the A/C stuff came from was a 1986, so the harness did not work on my truck. I was lucky enough to find one on eBay. Here are the two harnesses below with the connectors circled that are different. You can find the other end of it under the dash above where the evaporator is going to sit. Install the A/C switch on the dash and plug that into your existing harness as well.

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The A/C harness will plug into the main harness, thermistor, low pressure switch and another plug on off of the harness that the blower motor and resistor are run on. I will post pictures of where they go once I get mine in.
 
Last edited:

yotadude520

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I got my wiring harness in last night and went ahead and plugged it in. Here's the harness again:

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The 5 pin plug (or 4 pin if you're truck is a 1986 or older) plugs into this plug out of the main harness to the right of A. Then plug the larger plug into the A/C amplifier.

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2 plugs go into the low pressure switch and thermistor whereas the third plugs into the harness that runs the blower motor and resistor.

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Once this is in you're all done under the dash!
 

yotadude520

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Compressor

I highly recommend buying a new/re manufactured compressor if you’re going to be doing this install. It would be horrible to go through all this work only to find out the compressor you have is leaking. I bought mine at AutoZone, and since I got the A/C install kit which came with the drier, expansion valve, and A/C schrader valves I qualify for a lifetime warranty on it – which is awesome!

When you buy your new compressor put it next to your old one so you can make sure it’s the same. You’re going to notice that your new compressor doesn’t have the fitting for the A/C lines to go.

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You’re going to need to remove those fitting off of the old compressor and install them on the new one. To remove them you’re going to need a #7 metric allen key and a socket to break those screws loose. Once they’re loose, take them out and they’re going to pop right off the old compressor. You’re also going to remove the caps on the new compressor.

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With these fittings off I cleaned them off with some brake cleaner and a rag. DO NOT use any type of brush to clean these. You don’t want to scuff the mating surface where they meet the new compressor. Replace the O-Rings on these and reinstall them on your new compressor.

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Also on the line fittings are two valves which are used to charge the system with Freon. Using a valve core removal tool remove these valves and replace them with the ones provided in the kit. I also installed my R134a conversion fittings on the compressor as well.

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The compressor that I bought had no oil inside of it. After reading the FSM it calls for 2.0 – 3.4 fl oz of PAG oil in the system. I’m going to be putting in 2.9 oz (86 ml) of oil in my system as I feel that should be sufficient. Using a ML pouring cup I poured 40 ML into the suction side of the compressor and turned the clutch. The compressor has markings on each side so you know which is which. I’m going to put the remaining 46 ML of PAG oil in the drier to ensure that the system is properly lubricated per the compressor manufacturer’s instructions.

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Once the compressor is oiled and everything is good to go, attach it to the A/C bracket on the side of the engine block using 4 M8 x 1.25 x 90 bolts with a washer. KLF kept the original A/C bracket on the engine and had it fitted with a custom bracket for the York compressor he was going to use on his OBA system. I had to remove some studs on the bracket before I was able to bolt on my compressor. If your truck never had A/C, you’re going to need to install the correct bracket on your engine block. The bracket that I have on my 22RE has the idler pulley right below it.

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Once you’ve bolted on the compressor, you’re ready to move on to installing the condenser.
 

yotadude520

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Condenser/Drier

I originally had bought a Spectra condenser from AutoZone and it didn’t work because the fitting on the line going to the drier was too big. All in all it was just a POS – the quality just wasn’t there.

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I ended up ordering a brand new Denso (OEM) condenser for a 1987 4Runner. The 4Runner condensers have a smaller condenser in front of them to make up for the extra cab space in the 4Runner. Since I’m converting this system to R134a having a bigger condenser doesn’t hurt. The parts truck where I got all my A/C stuff from was a 1986 pickup, so I did have to find some things to make the 4Runner condenser work. You can see the condensers are exactly the same minus the smaller condenser on the 4Runner's.

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Swap over everything from your parts condenser (if you have one) over to your new one. This will include two brackets and two bushings that slip into the new one.

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To access where the condenser and drier mount, you need to remove the front bumper and grille. I don’t have any pictures of how to remove a stock front bumper or grille, but it shouldn’t be too difficult. Once you have it off it should look like this.

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There are two threaded holes where the condenser mounts with M6 bolts. There are two additional holes to mount it where the brackets go that you’ve just installed that use short M6 bolts with nylock nuts. The drier has it’s own separate mount where there are two holes behind the coolant reservoir. Before I installed my drier I remembered to put 46 ML of oil in it to ensure the system is properly lubricated per the instructions of the compressor manufacturer.

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Since the 4Runner and pickup condensers are different they have different hard lines that go to the drier. The 4Runner has a small line that goes from the smaller condenser to the drier. Here are the two different styles of lines. The top is for the 4Runner whereas the bottom one is for the pickup.

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It is possible to just remove the smaller condenser in front and you will have the exact same condenser as a pickup if you can’t seem to find the lines out of a 4Runner.

There is also another line that goes from the output side of the drier that runs across the condenser. This seems to be the same between the 4Runner and pickup but I’m not 100% sure. I was able to use the one I got from the 1986 pickup. You can see it below:

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Hooking It All Up

Including the two lines going from the condenser to the drier there are five lines for the A/C system.

-From condenser to input side of drier
-From output side of drier to the end of condenser
-From output drier line to evaporator

-From compressor to condenser
-From compressor to evaporator

The lines in bold are hard lines whereas the others are regular rubber A/C lines. I unfortunately did not take pictures of them before I installed them, but I really believe the only way you’re going to find these is to get them from a donor truck. I checked on eBay and could not find any of them. You can get the two rubber lines new on eBay, but the hard lines are nowhere to be found.

Condenser to drier
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Compressor to condenser & drier to evaporator (below)
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Condenser & evaporator to compressor
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Condenser to evaporator (smaller line) & compressor to evaporator
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Here are a few pictures of the line connections on all parts of the system. When installing the lines I cleaned them out with brake cleaner and compressed air. It is also very important that you replace every O-Ring in the system and lube them with PAG oil.

Reinstall your bumper and grille and now you're ready to charge the system!

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yotadude520

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Well I tried to charge the system last night and ran into a few issues. First of all, my A/C amplifier is bad so I need to get a new one. We jumped two wires and got the compressor to come on with the switch in the dash. We put the system under vacuum and it evacuated and held successfully. However when we went to charge the system we had absolutely nothing on the high side. We had only put in one full can and were diagnosing the high side issue when the line from the condenser to the compressor blew.

Unfortunately I think I got a faulty expansion valve from AutoZone. I'm going to have to pull the system apart again and check for any blockages in the condenser or any of the other lines. If there isn't any then the expansion valve is going to be replaced. I've got a new Denso one on the way.

I'll keep everyone posted on what I find out when I take it apart tonight.
 

yotadude520

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After my first attempt at charging the system (which resulted in a blown A/C line) I took apart the entire system and blew compressed air through everything to confirm I had no blockages. After finding none, the only thing that could've have been bad was the expansion valve.

I went ahead and ordered a factory Denso 475-0101 Expansion valve and installed it. It was the one that Toyota used from the factory so there's no stupid adapters or anything like that. Even came with the foam to go around the probe and was in a nice box. Got it installed and re-foamed the evaporator box.

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Evacuated the system on Saturday morning, it held for an hour and I started to charge the system - and it works!

I still can't seem to get the amplifier working and I believe my low pressure switch is also faulty as it did not shut the compressor off when there was a small amount of freon in the system. For now I have the amplifier bypassed and control the compressor by the switch on the dash. This will get me through Summer and I'll have the system evacuated and fix it down the road.

But for now, the AC is absolutely freezing! Literally feels like it's blowing ice cubes out of the vents. I couldn't be any happier with it. I'm going to put a thermometer on it and will let everyone know how cold it is here in Sunny AZ.
 

D21FJ60

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This is awesome. AC work is something I am wary of due to not knowing about them very well. AC in my 100 series has a leak somewhere so I will be doing baby steps.
I suppose you get a pass for not doing more to your 4runner
 
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Most everything has uv dye these days. If not, its probably worth the couple bucks to have a shop look.

This is awesome. AC work is something I am wary of due to not knowing about them very well. AC in my 100 series has a leak somewhere so I will be doing baby steps.
I suppose you get a pass for not doing more to your 4runner
 

D21FJ60

I'll get to it
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Most everything has uv dye these days. If not, its probably worth the couple bucks to have a shop look.
I spoke with Lance at Iron Pig offroad, which is a local well known and renowned crusier shop- hes an amazing asset to the community. He said theyre working overtime so give it a go with the UV dye and shoot him a message and he'll help me as best he can remotely since it may be something as simple as a gasket.
 

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