I just did a full refresh of my AC system in the 86 FJ0. It was hell because I had never done AC work before other than topping off Freon.
Maybe this will save somebody from the problems I came across. This is for those wanting to vacuum down and fill with Freon.
I wouldn’t suggest you fill yourself unless you have experience. I burned up a brand new compressor because of lack of knowledge. This was an expensive journey. Maybe not as expensive as having a shop do all of the work but there was a lot of headaches.
I am listing some tips and telling my story underneath that.
Tips:
I found these systems need about 28 to 30 ounces of R-134a. So that’s about 2.25-2.75 cans of Freon.
1. Use PAG 46 oil in the system if filling with R-134a. Replace the oil in the compressor if it comes pre-oiled. You want to put your own oil in. I put 3.5 ounces in the compressor and let the compressor sit with oil in it with the clutch/facing down for a while. Spin the compressor (not just the pulley) to get the oil moving through it before install. You should hear it gurgling. I don’t remember exactly how much oil I added elsewhere but it was a few ounces in the evaporator and few in the drier. I think a total of 7 ounces. Look around on MUD for suggestions but 3.5 in the compressor worked for me.
2. Always change the expansion valve and drier when working on AC. Add the drier last since the desiccant inside is moisture sensitive. The drier removes water from system.
3. If your condenser and evaporator has never been replaced go ahead and do that. Also low pressure switch near expansion valve should be changed. AC work is expensive and time consuming. Get it right the first time.
4. UV dye added to the system is a good idea. You could have a leak and you want to be able to find it easily. You can buy it at Autozone or Oreillys. I bought a cheap UV flashlight at harbor freight that works well for illumination.
5. You should not have to jump your compressor if the low pressure switch is working correctly. Also be careful and feel the compressor with your bare hand to check temp when first filling. If it’s getting hot give it a rest. Use your AC switch inside the cab or unhook the compressor if you have too. It will get warm but don’t let it get to the point where you can’t keep your fingers there.
6. Make sure all of your connections around the expansion valve/evap are nice and tight. You don’t want a leak there. It is a pain to take the evaporator box out again.
7. Most aftermarket expansion valves you will find have an adapter that connects it to the hardline. Avoid these if you can. Find a factory replacement style with no adapter. This is where I had a leak.
8. A drier failing and desiccant entering the system is rare but check to make sure there are no little brown beads in the system.
9. When filling the AC pull your choke or set the gas pedal so that you are idling above 1000rpm. You don’t want the AC amplifier keeping the compressor from running.
Once you get it filled you can set the idle up. This increases the rpms when the compressor is running. You set the idle up on the idle screw on the front of the carb. Turn clockwise to increase the idle. When you press the AC switch inside a vacuum gets pulled on the carb which triggers and idle up. Set it so that idle up is about 800rpms.
From the set the idle cutoff on the AC amplifier on the evaporator box. You turn the exposed knob down until the AC cuts off and then back it off a little bit to get the AC running again at 800rpms. You might have to play with this to keep your AC from cycling too much or never cycling off at all. Ideally you want the AC to cycle off when at a red light. But not on/off/on/off within a short timeframe. just play with it if you have to. And maybe it will be set just fine from the factory and that potentiometer hasn’t drifted from factory. Also there is a another red dial inside the AC amp that controls cycle based off of temp of the evaporator. Don’t touch it if you don’t need to. If it is cycling on and off adjust. If the compressor never cycles adjust until it kicks off and back that turn off some. You might have to play with it too. Ideally you won’t need to adjust anything on the AC amp.
10. Pay attention to how the wire connectors meet around the Evaporator box under the dash. These connect to the AC amplifier that controls idle up, low pressure cutoff, and temp sensor. There is one set you can mix up.
11. It helps to have a couple crescent wrenches when installing all of these parts. The AC line fittings have large nut sizes and there multiple places you need to stabilize the connection with a two wrench technique.
12. If you are not replacing everything make sure you do a flush.
13. You want vacuum to hold on the system for an hr at minimum. I left mine overnight just to be safe. Don’t rush that.
14. Look up a video of someone filling vehicle with the manifold gauges because you can easily mess that up.
15. If you are doing the changeover from R-12 to R-134a there are adapters you can buy from part stores and online. Be careful of the higH side because some adapters don’t fit well.
16. If you need new fittings or hoses look into ColdHose.com
they can make you up any AC line you need except for the hardline runs like around the condenser.
17. Full of Freon pressure: low side pressure should read around 40 when full. If it’s hot out a little above 40. High side should read like 220. It can be much higher when hot outside. Mine only got to about 210 and was blowing very cold. A good rule of thumb is fill until it blows cold and then watch your pressures. There is a science to Freon pressure And ambient air temps. Do a little research to help you wrap your head around it. Don’t Overfill
18. Make sure you oil the Orings you install on everything. Also double check fitment.
my story…
1. Compressor seized and belt was spinning on the pulley. The clutch was glowing red lol
2. I replaced the compressor, expansion valve, and drier (Also all new Orings)
I rented the pump and gauges and vacuumed down. It was holding vacuum so I thought I would be good to go. Wrong. I begin to try and fill and the low pressure switch wouldn’t kick on…huh so i guess I need to jump the compressor to get it going. So I jumped the compressor to the battery for a bit. Pressures are just not making sense. I should have stopped there. But no I continued on and connected the compressor back to the wiring harness. The compressor still wouldn’t kick on… so I jumped again to battery. A few minutes of this and I burn up a brand new compressor. I was sick!
3. I think for a while and figure I had blockage somewhere.
I pulled apart the AC lines and the whole evaporator assembly. Inside the lines and in the pressure valve I find these strange brown beads… oh it’s desiccant. The drier failed and those little balls clogged up everything. I have no clue how I missed it the first time but I did. Working in a dark garage I guess.
4. I decide to buy all new parts: we get another compressor, condenser, evaporator, evap hardline (used), pressure switch, expansion valve, and some fresh fittings and hose for the line that runs from the evaporator to the drier.
Put it all together and vacuum down. There is a leak. s***. At this point I decide I want some UV dye in there to see where that leak is. I did this pouring the dye into gauge line between the gauge and a can of Freon. Pull a good enough vacuum and open up the valve to let the freon push the dye into the system and jumped the compressor momentarily to send it around the system.
5. With a UV light I see no leaks in the engine bay. Dang. It’s in the evaporator box.
So I pulled the box out from under the dash again and sure enough I find oil and UV dye right where the expansion valve connects to the hardline.
6. Tighten everything up and pull a vacuum again.
Vacuum holds so I proceed with filling system again. As I start the filling process the compressor kicks on so the low pressure switch is working. But… I’m noticing that the compressor isn’t cycling on and off as the low side loses pressure to the high side. Bad news. You want the compressor to cycle when filling or Freon will not be passing through and moving oil through the compressor to lubricate. So I started manually pushing the AC on switch in the cab to let the compressor run for a bit then off. Let Freon build in low side the. Back on again. Repeated over and over while checking the compressor temp with my hand. If it got hot I would let it cool for a bit. It’s okay to let it sit for a while before cycling on to cause more heat. Finally I got enough Freon in the system to get oil moving and good lubrication in the compressor and I filled up 2.25 cans of r134a. Success. Blew cold.
7. 3 weeks later AC doesn’t work one morning. Sick again.
I was afraid I just destroyed another compressor. Turns out a hose blew. And the UV dye i previously added came in clutch and I was able to find the leak easily. The hose wasn’t crimped good enough I had made up at an AC shop. So I get a new hose made up (from another guy) and fill her up again. Blowing cold now for about a month with no issues.
Maybe this will save somebody from the problems I came across. This is for those wanting to vacuum down and fill with Freon.
I wouldn’t suggest you fill yourself unless you have experience. I burned up a brand new compressor because of lack of knowledge. This was an expensive journey. Maybe not as expensive as having a shop do all of the work but there was a lot of headaches.
I am listing some tips and telling my story underneath that.
Tips:
I found these systems need about 28 to 30 ounces of R-134a. So that’s about 2.25-2.75 cans of Freon.
1. Use PAG 46 oil in the system if filling with R-134a. Replace the oil in the compressor if it comes pre-oiled. You want to put your own oil in. I put 3.5 ounces in the compressor and let the compressor sit with oil in it with the clutch/facing down for a while. Spin the compressor (not just the pulley) to get the oil moving through it before install. You should hear it gurgling. I don’t remember exactly how much oil I added elsewhere but it was a few ounces in the evaporator and few in the drier. I think a total of 7 ounces. Look around on MUD for suggestions but 3.5 in the compressor worked for me.
2. Always change the expansion valve and drier when working on AC. Add the drier last since the desiccant inside is moisture sensitive. The drier removes water from system.
3. If your condenser and evaporator has never been replaced go ahead and do that. Also low pressure switch near expansion valve should be changed. AC work is expensive and time consuming. Get it right the first time.
4. UV dye added to the system is a good idea. You could have a leak and you want to be able to find it easily. You can buy it at Autozone or Oreillys. I bought a cheap UV flashlight at harbor freight that works well for illumination.
5. You should not have to jump your compressor if the low pressure switch is working correctly. Also be careful and feel the compressor with your bare hand to check temp when first filling. If it’s getting hot give it a rest. Use your AC switch inside the cab or unhook the compressor if you have too. It will get warm but don’t let it get to the point where you can’t keep your fingers there.
6. Make sure all of your connections around the expansion valve/evap are nice and tight. You don’t want a leak there. It is a pain to take the evaporator box out again.
7. Most aftermarket expansion valves you will find have an adapter that connects it to the hardline. Avoid these if you can. Find a factory replacement style with no adapter. This is where I had a leak.
8. A drier failing and desiccant entering the system is rare but check to make sure there are no little brown beads in the system.
9. When filling the AC pull your choke or set the gas pedal so that you are idling above 1000rpm. You don’t want the AC amplifier keeping the compressor from running.
Once you get it filled you can set the idle up. This increases the rpms when the compressor is running. You set the idle up on the idle screw on the front of the carb. Turn clockwise to increase the idle. When you press the AC switch inside a vacuum gets pulled on the carb which triggers and idle up. Set it so that idle up is about 800rpms.
From the set the idle cutoff on the AC amplifier on the evaporator box. You turn the exposed knob down until the AC cuts off and then back it off a little bit to get the AC running again at 800rpms. You might have to play with this to keep your AC from cycling too much or never cycling off at all. Ideally you want the AC to cycle off when at a red light. But not on/off/on/off within a short timeframe. just play with it if you have to. And maybe it will be set just fine from the factory and that potentiometer hasn’t drifted from factory. Also there is a another red dial inside the AC amp that controls cycle based off of temp of the evaporator. Don’t touch it if you don’t need to. If it is cycling on and off adjust. If the compressor never cycles adjust until it kicks off and back that turn off some. You might have to play with it too. Ideally you won’t need to adjust anything on the AC amp.
10. Pay attention to how the wire connectors meet around the Evaporator box under the dash. These connect to the AC amplifier that controls idle up, low pressure cutoff, and temp sensor. There is one set you can mix up.
11. It helps to have a couple crescent wrenches when installing all of these parts. The AC line fittings have large nut sizes and there multiple places you need to stabilize the connection with a two wrench technique.
12. If you are not replacing everything make sure you do a flush.
13. You want vacuum to hold on the system for an hr at minimum. I left mine overnight just to be safe. Don’t rush that.
14. Look up a video of someone filling vehicle with the manifold gauges because you can easily mess that up.
15. If you are doing the changeover from R-12 to R-134a there are adapters you can buy from part stores and online. Be careful of the higH side because some adapters don’t fit well.
16. If you need new fittings or hoses look into ColdHose.com
they can make you up any AC line you need except for the hardline runs like around the condenser.
17. Full of Freon pressure: low side pressure should read around 40 when full. If it’s hot out a little above 40. High side should read like 220. It can be much higher when hot outside. Mine only got to about 210 and was blowing very cold. A good rule of thumb is fill until it blows cold and then watch your pressures. There is a science to Freon pressure And ambient air temps. Do a little research to help you wrap your head around it. Don’t Overfill
18. Make sure you oil the Orings you install on everything. Also double check fitment.
my story…
1. Compressor seized and belt was spinning on the pulley. The clutch was glowing red lol
2. I replaced the compressor, expansion valve, and drier (Also all new Orings)
I rented the pump and gauges and vacuumed down. It was holding vacuum so I thought I would be good to go. Wrong. I begin to try and fill and the low pressure switch wouldn’t kick on…huh so i guess I need to jump the compressor to get it going. So I jumped the compressor to the battery for a bit. Pressures are just not making sense. I should have stopped there. But no I continued on and connected the compressor back to the wiring harness. The compressor still wouldn’t kick on… so I jumped again to battery. A few minutes of this and I burn up a brand new compressor. I was sick!
3. I think for a while and figure I had blockage somewhere.
I pulled apart the AC lines and the whole evaporator assembly. Inside the lines and in the pressure valve I find these strange brown beads… oh it’s desiccant. The drier failed and those little balls clogged up everything. I have no clue how I missed it the first time but I did. Working in a dark garage I guess.
4. I decide to buy all new parts: we get another compressor, condenser, evaporator, evap hardline (used), pressure switch, expansion valve, and some fresh fittings and hose for the line that runs from the evaporator to the drier.
Put it all together and vacuum down. There is a leak. s***. At this point I decide I want some UV dye in there to see where that leak is. I did this pouring the dye into gauge line between the gauge and a can of Freon. Pull a good enough vacuum and open up the valve to let the freon push the dye into the system and jumped the compressor momentarily to send it around the system.
5. With a UV light I see no leaks in the engine bay. Dang. It’s in the evaporator box.
So I pulled the box out from under the dash again and sure enough I find oil and UV dye right where the expansion valve connects to the hardline.
6. Tighten everything up and pull a vacuum again.
Vacuum holds so I proceed with filling system again. As I start the filling process the compressor kicks on so the low pressure switch is working. But… I’m noticing that the compressor isn’t cycling on and off as the low side loses pressure to the high side. Bad news. You want the compressor to cycle when filling or Freon will not be passing through and moving oil through the compressor to lubricate. So I started manually pushing the AC on switch in the cab to let the compressor run for a bit then off. Let Freon build in low side the. Back on again. Repeated over and over while checking the compressor temp with my hand. If it got hot I would let it cool for a bit. It’s okay to let it sit for a while before cycling on to cause more heat. Finally I got enough Freon in the system to get oil moving and good lubrication in the compressor and I filled up 2.25 cans of r134a. Success. Blew cold.
7. 3 weeks later AC doesn’t work one morning. Sick again.
I was afraid I just destroyed another compressor. Turns out a hose blew. And the UV dye i previously added came in clutch and I was able to find the leak easily. The hose wasn’t crimped good enough I had made up at an AC shop. So I get a new hose made up (from another guy) and fill her up again. Blowing cold now for about a month with no issues.
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. Hope this becomes a sticky as it’s spot on. Nice work.
