a/c recharging...high-low pressures?

[twb4525]

I plan on recharging the a/c in my 1993 ranger 4.0. does anyone know the correct high/low pressures for this year ranger? I plan on using an a/c manifold guage set.

the truck was originally r12, but converted over to r134a sometime before I got it.

thanks in advance,
tom

 

[adsm08]

You can't accurately recharge an A/C system by pressure. Pressure can change drastically with just a few degrees of ambient temp. The only accurate way to charge an A/C system is to completely evacuate it and then charge it by weight. Take the original amount on the R12 label and multiply by .9 to get the correct R134a amount.

 

[4x4junkie]

A shop I took mine to recommended against that... Charge it with the full weight, just using R-134a instead of R-12.

That's what he did with mine almost 6 years ago and to this day that dang thing still blows out at 38° even when it's 90-something out.

I do agree though, there's no real foolproof way to charge it to the correct amount other than to evacuate & recharge by weight (plus if it's low, there's likely a leak that you would need to repair anyway).
Do you know whether PAG-46 or ester compressor oil was used in the 134a conversion? (you will want to use the same)

 

[tinman_72]

Pick up a can of A/C Pro. It works wonders and includes everything you need.

http://www.youtube.com/watch?v=Wn0C9jPOAAQ

 

[adsm08]

Pick up a can of A/C Pro. It works wonders and includes everything you need.

Yes, A/C pro works wonders for charging the system to the incorrect level and causing more damage to the system.

If you read the fine print on their web site they even tell you that their product is a temporary solution and that even if you use it at some point you need to consult a trained professional to have the leak repaired and the system charged to the correct level.

 

[tinman_72]

Yes, A/C pro works wonders for charging the system to the incorrect level and causing more damage to the system.

If you read the fine print on their web site they even tell you that their product is a temporary solution and that even if you use it at some point you need to consult a trained professional to have the leak repaired and the system charged to the correct level.

Checked their website cannot find that. Where did you see it?
A/C Pro contains a sealant. I have used it before and had no problems in the three remaining summers before I sold the car. I have recommended it to two other people who have also had success.

 

[sblake01]

A/C Pro contains a sealant.

If you don't ever plan to have your system worked on by a 'pro' then that's fine. That sealant not only can cause damage to your a/c system but but also to the expensive recovery/recharge machine that shops use. If it works for you, that's fine, I guess but it's still a 'band aid' rather than a repair.

 

[sblake01]

You can't accurately recharge an A/C system by pressure.

Not completely true. You can with the right equipment and knowledge. I use my recovery/recharge machine and my thermometer/hygrometer. The latter gives me the ambient temp and humidity. Without these you’re really just guessing. I hook up the machine, engine off. I want to see pressures that are equal on both sides, and within a few degrees of ambient of the engine bay. R134a is pretty much 1:1 temp vs. pressure. But you have to take the temp of the container, aka the lines in the engine bay. Then I refer to the pressure/temperature chart in the vehicle's service manual, start the system and charge it to within range.

 

[Hoofhearted]

Checked their website cannot find that. Where did you see it?
A/C Pro contains a sealant. I have used it before and had no problems in the three remaining summers before I sold the car. I have recommended it to two other people who have also had success.

I'm no pro, like these guys, but I'd take their advice and stop using it- not just AC Pro but any that contain sealants or stop leaks.

I immediately understood that fixing a leak with additives in the refrigerant doesn't sound like a good idea- seems to me like fixing a leak in your pipes by adding turds to the water.

Besides all this, I've heard it said that NO manufacturer will warranty their product if you put these additives through their system.

In many cases it may be ok for a few years or longer, but as already mentioned, this is not the correct way to fix a leak.

It's truly like putting a band-aid over a bullet hole, but It's better than nothing I suppose if you're looking for a cheap and easy fix to your cold air problems- and you're not worried about permanent damage to your compressor.

 

[adsm08]

Not completely true. You can with the right equipment and knowledge. I use my recovery/recharge machine and my thermometer/hygrometer. The latter gives me the ambient temp and humidity. Without these you’re really just guessing. I hook up the machine, engine off. I want to see pressures that are equal on both sides, and within a few degrees of ambient of the engine bay. R134a is pretty much 1:1 temp vs. pressure. But you have to take the temp of the container, aka the lines in the engine bay. Then I refer to the pressure/temperature chart in the vehicle's service manual, start the system and charge it to within range.

Ok, with enough calculus I suppose anything is possible, but that sure does seem like using a whole ream of paper to write out all your work to show that the square root of 100 is 10. It would be easier to just suck her down and put the right amount in and be done with it.

Also, since the OP was planning to go buy a can of AC pro or some such, and was asking questions about how to charge the system I am betting he has neither the equipment nor the knowledge to do it that way and get it right.

 

[sblake01]

Ok, with enough calculus I suppose anything is possible, but that sure does seem like using a whole ream of paper to write out all your work to show that the square root of 100 is 10. It would be easier to just suck her down and put the right amount in and be done with it.

Also, since the OP was planning to go buy a can of AC pro or some such, and was asking questions about how to charge the system I am betting he has neither the equipment nor the knowledge to do it that way and get it right.

It takes no more time to do it either way if you have the equipment. All the info I need is right in front of me....including a refrig. identifier and sealant detection kit and all the charts on my laptop........that was my point. I wasn't trying to argue with you. I've used that method to 'fix' systems that have been charged with auto parts store cans as long as they didn't have sealant in their system.

 

[twb4525]

Ok, with enough calculus I suppose anything is possible, but that sure does seem like using a whole ream of paper to write out all your work to show that the square root of 100 is 10. It would be easier to just suck her down and put the right amount in and be done with it.

Also, since the OP was planning to go buy a can of AC pro or some such, and was asking questions about how to charge the system I am betting he has neither the equipment nor the knowledge to do it that way and get it right.

no, I've got a/c manifold gauges. I was just inquiring on the high/low pressures vs temp. etc... since I don't have a service manual for my truck.

I wont use ac pro.

 

[4x4junkie]

It's also possible to do it simply by measuring the temperature of the inlet fitting to the evaporator coil vs. the temperature of it's outlet.
If they are within 10°F of each other, there is sufficient freon inside the system and some amount of excess freon should be stored in the accumulator.

A greater temp differential would mean the freon is completely boiling off into a vapor prior to reaching the outlet because there's insufficient quantity in the system.