orifice valve direction and other V8 swap related AC questions.

[JoshT]

Background: Just finished up a V8 swap from a 2000 Explorer into my 1999 Ranger. At purchase I thought the Explorer AC was working, but it was a cool (or cold) day and the EACT wouldn't let me set the target temperature lower than 60. Apparently I was wrong and I think what I felt was actually just cold outside air coming through the vents. After swapping the complete ac system over intact (without opening and discharging it) I discovered that it wasn;t working, and the compressor clutch wouldn't cycle. Turns out the system was practically empty, not enough pressure to close the low side switch. So new o-rings, new orifice tube, and new receiver dryer were installed. Turns out I also have a bad compressor because aftger vacuuming and adding an initial charge, with the compressor running it won't build pressure on the high side. We did check, the system is air tight, no leaks. Held 16" of vacuum for around 12 hours before getting a stronger pump to reach the 30" mark.

First, there is some conflict over what direction the orifice tube is supposed to install.

Dad pulled the old tube out when I wasn't looking. I installed the new tube without consulting him. More studying that night lead me to believe that I installed it backwards. He checked the next morning and says it was the same direction as the old one. That would be with the Red end of the tube towards the evaporator core (dash). I highly suspect the system has been opened previously and likely not reassembled correctly.

This morning after further consulting the internet and carious AC threads, I'm almost positive that the Red end is supposed to be towards the condenser (radiator support). Refridgerant trivels from the condenser to the evaporator, so that is where the screen/filter should be to catch debris and such. Also it sounds like there is an arrow on the tube that should be pointed in direction of flow, it's pointed towards the white end.

I consulted the FSM and it isn't clear on that either. Since I have to re-open the system anyway I'll ask the experts, or atleast phone a friend. What direction is the orifice tube supposed to be installed?

Second is what components to use to fix the compressor problem. My 99 Ranger's AC system was working well. The compressor is the same between the 4.0 and 5.0, just different sized pulleys that can be swapped out. From my reading the 4.0L Ranger condensor should work with the 5.0L hoses if it will clear the radiator. Seems that it might prefered by the 5.0L Explorer crowd since it mounts to the core support instead of the radiator. Any reason to not re-use the 4.0L components?


For consideration with responses, we can do most of the work ourselves. Last time we did it was installing an all new system in a Probe about 15 years ago. I bought a vacuum pump today and we can rent a manifold from local auto parts store, or dad is talking about buying new hoses (or manifold set) to replace his dry rotted ones. Aside from evacuating/recovery of the old freon, we can do the work, just not a lot of experience to draw from. The recovery portion I'll hire out.

 

[Uncle Gump]

The screen end goes toward the high side.

The opposite end has a couple tabs that the removal tool typically locks onto.

 

[85_Ranger4x4]

Kinda neither here nor there but I am using a 91-94 Ranger condenser with my Explorer compressor...

 

[Uncle Gump]

So after you put in your initial charge of refrigerant... did the pressure equalize in the high and low sides? What was the pressure? How much refrigerant was added?

Also... where the lines meet the compressor... there isn't service valves is there? I don't think there should be... but you never know in some cases what's been done. Similar to this...

Those are used to isolate the compressor/lines and have to be mid seated to allow the system to function.

Did the compressor engage on its own or did you have to jump the low pressure cut off to get it to go.

 

[JoshT]

The screen end goes toward the high side.

The opposite end has a couple tabs that the removal tool typically locks onto.

Well, high side would be towards the condenser, but both ends have a screen.

Red end has a large screen, white end has a small screen. I'm going to assume that the tabs you refer to are the little ones sticking out on the red section in the picture above.

We don't have the tool. The few we've done were able to grab and gently remove with needle nose pliers.

So after you put in your initial charge of refrigerant... did the pressure equalize in the high and low sides? What was the pressure? How much refrigerant was added?

Also... where the lines meet the compressor... there isn't service valves is there? I don't think there should be... but you never know in some cases what's been done. Similar to this...

View attachment 108011

Those are used to isolate the compressor/lines and have to be mid seated to allow the system to function.

Did the compressor engage on its own or did you have to jump the low pressure cut off to get it to go.

Yes, pressure equalized. At or very close to 70 PSI. EDIT: I guess it would have been just below 70 since the low pressure switch didn't close. Couldn't tell you in the refrigerant quantity. We were using the small 12oz R134a cans, the system wasn't taking more than that initial charge and, best I can tell, not much of the can was used.

No service valves.

We had to jump low pressure switch to get compressor to engage.

 

[Uncle Gump]

Ok.... the red end goes toward the high side. It's been awhile since I've had one of those out. The ones I've seen also have tabs on the white end that engage the tool. Hard to say what parts look like any more.

So when you jumped the switch to start the compressor... you say it didn't build high side pressure. Did it drop the low side pressure?

If you didn't even get an entire 12oz can in the system... that's not nearly enough to build any high side pressure. IMHO

 

[JoshT]

Don't recall. I was observing, but dad was watching the gauges. I want to say that it didn't do anything but spin the clutch. No changes in the gauges that I noticed.

 

[JoshT]

If you didn't even get an entire 12oz can in the system... that's not nearly enough to build any high side pressure. IMHO

Seems to me like it didn't hardly get any into the system, not much of that can at all. Before writing off the compressor, we might need to try again in case we messed something up in the process.

 

[JoshT]

If you didn't even get an entire 12oz can in the system... that's not nearly enough to build any high side pressure. IMHO

Just talked to Dad, he agrees that it hardly took anything from the 12 oz can. With that it was up around the 70 psi mark if was reading the gauge right.

 

[broncc]

Like this. You want more surface area to collect residue from the compressor before going through the orifice. I believe the high pressure output from the compressor goes through the condenser and along the passenger frame rail into the orifice.

 

[Uncle Gump]

I think you might want to flip the orifice... reseal it up... pull vacuum. Ensure it holds.

Have a bucket with hot water... dump in an entire can of refrigerant in the system. Placing the can of refrigerant in the hot water will raise the pressure in the can and force it into the system. You can also warm the can with your hands but hot water works better. That entire can should go into the system before you ever start the truck. Read gauges....pressure should be equalized. Then start the truck... turn it to max a/c. The clutch should engage on its own without jumping any thing. It may cycle quick... because the system is low. Tap another can... slowly fill only on the low side... only with can upright so you don't dump in liquid. Fill until full.

 

[JoshT]

View attachment 108035
Like this. You want more surface area to collect residue from the compressor before going through the orifice. I believe the high pressure output from the compressor goes through the condenser and along the passenger frame rail into the orifice.

That is how it is currently installed. I'd initially inserted it the other way on Saturday, but was bothering me all afternoon so I did some digging. Results of that digging were inconclusive but leaned towards the orentation you indicated, so we flipped it around on Sunday.

I think you might want to flip the orifice... reseal it up... pull vacuum. Ensure it holds.

Have a bucket with hot water... dump in an entire can of refrigerant in the system. Placing the can of refrigerant in the hot water will raise the pressure in the can and force it into the system. You can also warm the can with your hands but hot water works better. That entire can should go into the system before you ever start the truck. Read gauges....pressure should be equalized. Then start the truck... turn it to max a/c. The clutch should engage on its own without jumping any thing. It may cycle quick... because the system is low. Tap another can... slowly fill only on the low side... only with can upright so you don't dump in liquid. Fill until full.

Even if it is installed in the direction broncc indicated?


We're going to try itr again one afternoon, maybe tomorrow. Will try the bucket of water.

Since you mentioned it, during that initial can fill without the truck running, is it ok to turn can upside down and let liquid go in?

Also during that initial can, should it go into the low side only, or can it go into both sides? I know that it needs to be low side only when truck is running. I ask because you say that the pressure should be equalized, but I think that should also happen filling low side only.

What is the likely problem if it won't take that full initial can?

If the compressor clutch does not engage what would cause that? It would have to be an issue with the low pressure switch, but the wiring has been checked good and the switch is known good. The one currently installed is the same switch that was working perfectly in my truck for the last decade, unless it failed after removing it from the truck 3 weeks ago.

If the clutch engages and pressure doesn't build on high side, that about has to be a bad compressor right?

Sorry about all the questions I don't have the setup here to look at and I'm trying to visualize te process. Want to make sure I'm working through it right. I'd prefer to not find out that I replaced a good compressor and condenser because I did the steps wrong trying to charge the system.

 

[lil_Blue_Ford]

So either condenser will work, I think dad’s swap we used the Ranger one and I think I ended up using the Explorer one on mine. Really doesn’t make a difference. Only the hose for the compressor and the pulley on the compressor changed as far as I know otherwise.

I’m not really sure what to tell you on the rest of it. I believe the orifice tube goes white end in and the red side towards the front of the truck if I remember right, but I could be wrong. When I did the AC in my 92 I opened both sides of the manifold to vac down and let it run a couple hours before closing up and shutting down. Let it sit overnight, then when it didn’t change overnight I put as much in as it would take before starting it and running max AC to fill the rest of the way. You would have to check the fill amount, but if I remember right it should take a little over two 12 ounce cans.

 

[Uncle Gump]

I think @broncc is showing arrow as direction of flow.

With system not running... you can turn can upside down to allow liquid charging. You can also charge on both high and low sides. Just give ample time for liquid to disperse and pressure to equalize before you engage the clutch. Once running... only charge with vapor on the low side.

I don't know the exact ON/OFF thresholds of the low pressure... but it typically operates right in the neighborhood of 35psi. The compressor should come on above 35 psi... and cycle off once it drops below 35psi...

 

[JoshT]

So either condenser will work, I think dad’s swap we used the Ranger one and I think I ended up using the Explorer one on mine. Really doesn’t make a difference. Only the hose for the compressor and the pulley on the compressor changed as far as I know otherwise.

I’m not really sure what to tell you on the rest of it. I believe the orifice tube goes white end in and the red side towards the front of the truck if I remember right, but I could be wrong. When I did the AC in my 92 I opened both sides of the manifold to vac down and let it run a couple hours before closing up and shutting down. Let it sit overnight, then when it didn’t change overnight I put as much in as it would take before starting it and running max AC to fill the rest of the way. You would have to check the fill amount, but if I remember right it should take a little over two 12 ounce cans.

My understanding is the key difference in condensers is the way that they mount. Ranger V6 mounts to the core support. Explorer V8 mounts to the radiator. If I replace the condenser I will be using the Ranger one since it appears to clear with the V8 radiator. The heck with trying to attach and separate the radiator and condenser int he engine bay when service is needed. I did it once and understand why explorer owners hate it. If I had realized that the system was empty I wouldn't have even done it once.

That is how the tube is currently installed and jives with what @broncc and @Uncle Gump said. Fill amount is 1lb 14 oz per the lable on the radiator support. That's 30 oz or about 2.5 of the little 12 oz cans. More I think about it, more I suspect we did something wrong during the fill process. We verified the system was tight the other night and it hasn't been opened, just need to get it pulled back down and try again.