FZJ80, R134A Air Conditioning System Rebuild How To (1 Viewer)

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Thanks to the contributions of many very knowledgeable ih8mud contributors I was able to refresh the AC on my 1997 FZ 80.

A few of those contributors surely saved me a lot of time, $$, mistakes and reworking. @flintknapper and @alia176 stand out in my mind though I'm sure there were a number of other valuable contributors to the AC information that I read. Alia176 has a great writeup that shows the easy way to get the evaporator core out, which surprisingly only took about 20 minutes on my first try. FlintKnapper seems to have deep knowledge and experience with automotive AC systems and has done a great job of clearly explaining the hows and whys of servicing and recharging an AC system. Flint's posts in particular gave me the confidence to proceed.

Here are a few of the threads that I used. These cover a lot of ground and not all applies but you can learn a lot from them:

In preparation for this job I compiled a lot of the information that was relevant for my project including parts lists and how to guides and I thought I'd share my notes here in case it helps anyone else wanting to overhaul the AC in their 80.

Parts replaced (using Toyota or Denso in all cases):
  • compressor
  • evaporator
  • expansion valve
  • dryer
  • condensor
  • AC and Alt belts
Costs:
  • $845
    • Including parts, refrigerant, oil, flush agent, having the system evacuated at a shop ($60), etc.
    • I rented the vac pump, gauges and flush tool (free from local auto parts store)
  • 7 hours wrench time
    • This was just the time spent working on the system and doesn't include research, parts acquisition, etc. Extra time was spent cleaning, etc. and I worked at a slow pace. Vac down and vac hold testing added time that I didn't count for the most part as I wasn't actively working on the 80.
    • I found that this broke into 3 work sessions nicely. 2 hours for evaporator remove and replace, 2 hours for belts/compressor and then 3 hours roughly for the rest.
Tools:

There are a few specialty tools needed for this job. I luckily had an air compressor, used to blow out, flush and again blow out the AC system lines a few more times. I also had an accurate scale, which I used to measure the refrigerant cans before/after use so that I knew how much was added to the system. I was able to rent (for free) the AC tools that I needed easily and use basic hand tools for the rest of the work.​


Results:

The AC in my 80 worked well before but it is noticeably cooler now. I'm really glad that I did this myself as I was able to spend extra time cleaning under the dash, the radiator and trans cooler. Details like straightening out fins, greasing fasteners, etc. wouldn't have been attended to by a shop I'm sure.​
The following posts will contain the parts list and step by step guides I followed, etc.
 
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Joined
Sep 15, 2016
Messages
1,109
Location
Chattanooga, TN
Parts:

Most of the parts I purchased came from RockAuto. There are equivalent sources and a few of these parts went in and out of stock during my planning process so you may have to shop around.

1996 TOYOTA LAND CRUISER 4.5L L6 A/C Compressor | RockAuto - https://www.rockauto.com/en/catalog/toyota,1996,land+cruiser,4.5l+l6,1276691,heat+&+air+conditioning,a/c+compressor,6628


AC compressor - 10PA17C471 1166$199.00denso, apparently comes with oil but drain it and refillMore Information for DENSO 4711166 - https://www.rockauto.com/en/moreinfo.php?pk=2023250&cc=1276691&pt=6628
AC Drier88470$17.00DENSO 4780503More Information for DENSO 4780503 - https://www.rockauto.com/en/moreinfo.php?pk=2993988&cc=1276691&pt=6972
AC Expansion Valve$16.00densoMore Information for DENSO 4752005 - https://www.rockauto.com/en/moreinfo.php?pk=7570448&cc=1276691&pt=6788
evaporator476-0045$146.00densoMore Information for DENSO 4760045 - https://www.rockauto.com/en/moreinfo.php?pk=4717743&cc=1276703&pt=6768&jsn=1347
AC condensor477-0554$93.00densoMore Information for DENSO 4770554 - https://www.rockauto.com/en/moreinfo.php?pk=870781&cc=1276691&pt=6708
orings$15.00More Information for UAC RS2580 - https://www.rockauto.com/en/moreinfo.php?pk=9836012&cc=1276691&pt=13290
pag oil$8.008 ozs. of PAG 46 oil, compressor may come with oil in it but drain it and refill, "I like to put about an ounce of oil in the Evaporator, 1/2 ounce in the drier, couple of ounces in the Condenser and the rest in the compressor (8 ozs total)."More Information for FOUR SEASONS 59007 - https://www.rockauto.com/en/moreinfo.php?pk=9661836&cc=1276691&pt=6928
AC flushing agent$17.00Supercool 22779 $48.74 A/C Flash Flush, Solvent Based Can, 1 gal. | Zoro.com - https://www.zoro.com/supercool-ac-flash-flush-solvent-based-can-1-gal-22779/i/G3592346/
r134 a$30.003 of the 12 oz cans, roughly $10 apiece, avoid leak repair or other additives
AC gaugesrent gauges/pump/flush tool from oriellysA/C R134A Manifold Gauge Set - https://www.harborfreight.com/ac-r134a-manifold-gauge-set-62707.html
vacuum pump2.5 CFM Vacuum Pump - https://www.harborfreight.com/25-cfm-vacuum-pump-61245.html
AC flushing toolGreat Deal on Mastercool 91046-A at ToolPan.com - https://www.toolpan.com/Mastercool-91046-A--AC-System-Flush-Kit-_p_79.html?gdffi=d5de8d975e554fe98677ff5f83efd439&gdfms=FC249A8AE1524C99B2C825CEC9CDE552&gclid=CO2Glv2nzs4CFQSTaQoddokJhw
air compressor drier$15.00inline type to keep water out when blowing lines
nylog for all fittingsnylogAmazon product
 
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Joined
Sep 15, 2016
Messages
1,109
Location
Chattanooga, TN
Tasks:
Most of the following is copied/adapted from @flintknapper and @alia176 - Big Thanks for their contributions!​

Replace system components:

general:
Make sure ALL crud is out of the system before it's buttoned back up​
Use new O-Rings and (Nylog) on your fittings​
fittings at the condenser​
A/C Line O-Rings connected to the A/C Condenser​
the liquid line/suction hose at the firewall​
the schrader valves in the service ports​
flushing lines and oiling the system will be the last step before re-connection of all lines to new components​


Evacuate the system
have a shop with the equipment handle this​
was $60 in 2022​


Install new evaporator/expansion valve
Tools needed:​
long phillips screwdriver​
10 mm socket (shallow and wobble)​
12" ratchet extension​
10 mm box end wrench/gear wrench​
1. separate the two hard A/C lines at the firewall from the evaporator unit​
clean the area first​
2. remove brace below glove box​
remove glove box, speaker, hardware, etc. to allow this​
there's a hidden screw on left/driver end of brace​
3. remove air box​
remove and disconnect black box on air box​
remove 3 10mm nuts at topleft, topright, mid right of air box​
remove bottom nuts/screws from airbox​
disconnect electrical connectors as needed​
pull air box​
4. split then clean air box​
cut foam at joints first to keep it from tearing​
5. replace evap and txv​
tape over the ac line connection holes to keep dirt out during reinstallation​
6. clean under dash airbox area​
it will be dusty/dirty​
7. reinstall air box​
make sure drain hose is installed and completely throught the firewall grommet​
leave tape over the evap connectors and lines disconnected for flushing later​


replace compressor and AC/ALT belts
check idler bearings and update all as needed​
tape over compressor openings and leave lines disconnected for flushing later​
replace condenser and drier
remove:​
grill​
center/vertical brace​
hood safety latch/hook​
turn signals​
unmount but leave connected:​
trans cooler​
headlights​
horns​
hood retainer latch/socket​
before reconnecting lines flush them out (See step below)​
add oil to pump, condensor, drier before re connecting lines (see step below)​
this needs to be done before these components are installed​
install new seals w nylog on each joint as lines are re-attached​


Flush the lines

use flush agent​
maybe follow with den. alc​
"When blowing out the lines it is important to block the escape route of line/component with your finger and let pressure build up.​
Using a blowgun with a rubber tip apply air at one end while blocking the other, then quickly remove your finger.​
This will cause a very forceful release of the air pressure and will carry any liquid and debris with it.​
Once you no longer see a 'mist' discharging, you should be good to go.​
But make sure to drain your air compressor frequently as you go, water from the compressed air will build up in it.​
We don't want that in the lines or components. "​

Oil the system (8 ozs total)
put about an ounce of oil in the Evaporator (if you remember to do this before installation)​
1/2 ounce in the drier​
2 ounces in the Condenser​
the rest in the compressor​


Vacuum the system after replacing components, flushing then re-attaching lines
use an A/C Vacuum Pump and an A/C Manifold Gauge Set.​
Use a decent pump to achieve 28-30 in hg vacuum.​
vacuum the system with both the high side and low side valves open​
evacuate the system for at least 45 minutes to remove any moisture​
a few hours if the system has been open for long​
Make sure it holds vacuum for at least 30 minutes.​
If it does not, you may have a leak in the system, find the leaking component and repair or replace it​


Charge the system:
R134A -​
1.76 to 1.98 lbs​
29.98 oz +/-1.76 oz​
Note on charge:​
I used a kitchen scale that is very precise to weigh my cans before and after filling to measure exactly how much refrigerant went into the system.​
There was a very small loss of refrigerant in the line purge/connection steps but I doubt it was very significant.​
I decided to add 31 oz of refrigerant to pad for any line losses. This is still a little below the "max" fill level.​
Conditions:​
ENGINE OFF​
System has been pumped down (deep vacuum) to between 28-30 inHg and has held vacuum for at least 30 minutes​
High and Low side hoses still connected​
Yellow charging hose disconnected from pump​
All valves closed​
valves were closed with vacuum pump still running to avoid losing any vacuum​
1. Connect yellow hose to can using appropriate adapter.​
IF using a side piercing adapter, install/pierce near the top or bottom of can (not in the center).​
We are going to invert the can so the liquid is nearest the piercing point later when we charge.​
2. Slowly unscrew the fitting of the yellow hose at the manifold gauge just until a small amount of refrigerant escapes past the threads, then re-tighten.​
This will purge any air (atmosphere) from that line and prevent any from entering the system.​
Some hoses have a shrader valve at that location that you can depress to do the same thing. Just be sure to purge the line.​
Be careful! Just barely crack the fitting to let a little refrigerant out.​
3. Invert the refrigerant can so that the liquid refrigerant is nearest the 'tap' (adapter) and keep it in this position.​
4. Slowly open the high side valve (until fully open) while making sure the can stays inverted, do not shake, just let the refrigerant be drawn in.​
You will physically be able to feel the can getting lighter. It shouldn't take too long (typically less than a couple of minutes).​
The Deep Vacuum will pull the refrigerant into the system.​
As this process nears its end...the can will become quite cold and the outside might even frost over.​
5. Once you are satisfied the can (approx. 12 ozs) has gone into the system, shut off the high side valve, we won't be using/opening it anymore.​
Leave the hose hooked up, we still need it for gauge readings later.​
6. At this point you are ready to finish filling the system via the LOW SIDE port.​
There is no more 'vacuum' in the system, we now have a certain amount of pressure (depending upon ambient temp).​
All future refrigerant will be drawn in as a VAPOR (we don't want liquid, or only very small amounts) going through the compressor.​
This will be drawn in by the compressor itself and through the LOW SIDE port.​
7. So...with High and Low side valves CLOSED, we are ready to connect another can of refrigerant to the yellow hose (with adapter).​
Connect another can, then just as before....'purge' the yellow line at the manifold connection​
(just let a little refrigerant escape, then re-tighten it, or use the shrader valve if so equipped).​
8. I like to hand turn the compressor 10-15 revolutions (belt(s) off) before installing the belt and running the compressor​
to insure it turns freely, has no liquid refrigerant in it (that can slug it) and to distribute some of the oil prior to start up.​
this extra step is up to you.​
9. Now lets start charging the remaining amount of refrigerant (whatever amount your vehicle calls for) as a VAPOR into the low side port.​
With the refrigerant connected and that line purged, we now need to purge the low side line (blue line).​
Just slowly crack that fitting (just as you did the yellow line) until a little bit of pressure escapes, then tighten it back up.​
Now we are ready to go.​
10. With your A/C on 'high' and the windows (or doors open), start the engine and your compressor 'should' already be running (clutch engaged).​
Make sure your refrigerant can has the tap facing UPWARD...so that only gas/vapor will be drawn out.​
Remember we don't want liquid refrigerant going through the compressor​
(at least not your first time, pro's and experienced DIYers know how to 'force' feed it, but DON'T do it for now).​
11. Slowly....open the low side valve and allow a small amount of refrigerant to be drawn in.​
DO NOT fully open the valve, DO NOT shake or invert the can at this point.​
Just open the valve about a quarter turn and watch your low side gauge.​
IF the pressure goes above 85-100 psi, turn the valve off for a minute or so and let the system 'settle' or open the valve to a lesser degree.​
This is going to take some time, so don't rush it.​
Depending upon the ambient temperature and humidity....it can be difficult to get the remaining charge of refrigerant into the system at times.​
Can submerge the can in warm water to help the process​
12. Continue to charge the system based on WEIGHT of refrigerant, not gauge readings (for a full system recharge).​
We will use the gauges to fine tune the charge later if need be.​
 
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Joined
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And finally, some general notes:

Most of these are again from @flintknapper - Thanks again!​

ac charging:

Go slowly​
be sure you have turned off all valves before connecting cans of refrigerant​
be sure to PURGE the low side line and refrigerant line each time BEFORE opening any valves to charge the system.​
Even small amounts of air and moisture will affect the performance of your system.​
Make sure you have pulled a deep vacuum on the system (28-30 inHg).​
This will remove air and moisture.​
If the system has been open to atmosphere for very long, then plan on pumping it down for a couple of hours or more.​
It takes time to boil off and extract the moisture.​
The point of creating a vacuum (besides removing the air) is to remove the moisture in the system.​
It has to boil off.​
The less pressure on the water vapor the lower its boiling point.​
For instance at approximately 29 inHg. water will boil at about 76° F. So the more vacuum we can maintain, the better.​
Moisture in the system can be handled by the desiccant in the drier, if not too much.​
But if too much...it will migrate to the TXV and Evaporator and freeze up (blocking your system).​
So let's just do it right the first time.​
For best results you need:​
1. Properly functioning components​
2. A clean system (no contaminants such as air, moisture, stop leak, etc...)​
3. Leak free components (compressor, lines, drier, evaporator, condenser).​
Refrigerant is a NON-Consumable, it can only escape via leaks or be compromised by contaminants.​
4. Proper amount of Oil and Refrigerant.​
So starting with a new or completely evacuated system is the easiest of all scenarios.​
We know how much of everything we need, we know (or should know) the condition of everything).​
It's partially filling or diagnosing a system that is hard. Not this."​
When charging a NEW/Evacuated system....​
don't rely on the gauges to tell you how much.​
The system is designed to work best using a specific amount of refrigerant.​
So 'weigh' it in. Then use the gauges to fine tune it and check for proper function.​
The reason(s) to liquid charge the system (initial charge).​
1. Liquid charging the first can/12 ozs. into the high side (Into Vacuum) gets 12 ozs. (if using disposable cans) into the system quickly.​
Typically less than a minute.​
2. Liquid charging (into the high side into vacuum) lets you get at least 12 ozs. of refrigerant into the system​
so that it can carry the compressor oil (lubricant) with it right from start up.​
You will also have enough pressure to activate the low pressure sensor...​
so the compressor clutch will operate right away when you go to finish filling the system (via the low side as a vapor).​


general ac troubleshooting

"You should have 'some' reading of the static pressure IF there is any refrigerant in the system.​
It should be roughly equalized (showing about the same pressure for both sides) when the system is off and the gauges are hooked up to the high and low side.​
There is a specific pressure reading (static pressure) for every corresponding degree in temperature for all refrigerants.​
In your case (134a) for example, at 80° F you should see about 88 psi of static pressure IF you have enough refrigerant in the system that some portion of it is liquid."​


"IF your condenser (regardless of type) is working correctly....you will have from 20-40° F. difference between the inlet side and outlet side.​
Less than 20° F. and you have either a dirty (outside) condenser or poor airflow. More than 45-50°F and you likely have an internal obstruction (partial). "​
 
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Comet

Knower of little, master of less.
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Sub. Doing this later in the summer.
 
Joined
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Location
Chattanooga, TN
Good luck with the project @Comet , it's very doable and should yield many more years of cool operation once done.

I didn't take many pictures during the work but these notes were meant to be a guide that I could print and follow so I never recorded photos. There are good ones on all parts of the AC system here on mud, including in the threads I linked to above. I'm always impressed by the folks that take photos as they do work on their trucks and then post them up in their writeups!

Here's my main photo from this project, of the evaporator box just before it went back in.

20220502_205137.jpg
 
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