A/C issue on '98 Explorer

[Denisefwd93]

High side pressures seem to scare people, not just in Automotive air conditioning either.

When we started using R410A in the new generation of central air systems. Many people (me included) thought 410A has "scary" hi side pressures. Many contractors and even more DIYers were under charging units and they weren't cooling properly. Fortunately we picked up a number of accounts just because of that misunderstanding.

Example: R410A with a 90° ambient temperature, we would arrive around 400 psig head pressure!

 

[scotts90ranger]

Thanks! I'll dig into that information tonight, gotta dig into some physical projects before it gets too hot outside, it's only about 80 out now, gonna be in the mid 90's here shortly... I'll try to go in informed this time . I was going off of a chart like that for the high end when I connected the can of refrigerant, it was around 75 outside and I was trying not to go too high of pressure... maybe should have just tried higher pressure...

 

[Denisefwd93]

It's pretty hard to get "too" high a high side pressure. I think people think high pressure = explosion. not likely on AC systems like this. only way it could conceivably be dangerous is if someone blocked or kinked the compressor discharge line before the condenser. Then it could build a static pressure and pop off the RV or blow a hose.

Just play with low side servicing. I'm kinda of sure you will get it cooling. this is the good thing about "ACPRO" kits, most people do ok and wind up with cooling for the season then forget it until next year LOL

 

[4x4junkie]

If you want to try just topping off the system w/o opening it, then my suggestion would be to fill it with refrigerant until the evap outlet fitting (upper line) suddenly becomes cold (to within 5-10°F of what the lower fitting is), then maybe add in one or two additional ounces if the outside temperature isn't real hot (if it's 95°F or higher, then stop adding just at the point the upper line turns cold).
Make sure whatever product you use DOES NOT contain any leak sealants, as that shit will do far more than just gum up any leaks (it should contain only R-134a freon together with PAG-46 oil, plus maybe a UV dye for detecting leaks, which is fine, and probably desirable in this case).

Just know that there is some chance by doing it this way that the amount of oil in the system could end up incorrect which (at best) can reduce cooling capacity, or (at worst) lead to compressor failure (and is why I always like to flush things and start fresh on systems I don't have a full history on).
Additionally, each time you attach the can fitting, the tiny amount of air that is contained within the fitting & valve gets pushed into the system along with the refrigerant, so after doing this enough times, you could start to lose system performance for that reason as well.

My suspicion though is you'll probably revisit this at some point because it is already known you have a leak (how else would it get so low?), the question now is; just how fast is the leak?

 

[kimcrwbr1]

A single drop of moisture can destroy the compressor from the acid it creates. There are acid test kits to determine ifthe system needs to be flushed prior to installing a new compressor. Every time you open up a system you get water intrusion from relative humidity that is why you evacuate the system to remove all non combustibles. Moisture begins to boil off around 800 microns but it can take some time to remove the moisture that gets mixed with the oil. Pull a deep vac for at least two hours overnight even better especially if to left the system open for any extended period. The rise and fall of barometric pressure will load the system with moisture the #1 killer of compressors.

 

[Denisefwd93]

"non-combustibles" I'm sure it was meant to say non-condenseable.

Wow just wow, looks like the jury would have you tear the whole system apart even before you find the leak. Most technicians would probably just charge it up add UV dye and send you on your way with the with the disclaimer saying you will probably need to have it charged leak found & fixed sometime in the future. This is possible because R134a is largely unregulated even though it's against the law to vent it to the atmosphere although everybody does

 

[4x4junkie]

Wow just wow, looks like the jury would have you tear the whole system apart even before you find the leak. Most technicians would probably just charge it up add UV dye and send you on your way with the with the disclaimer saying you will probably need to have it charged leak found & fixed sometime in the future. This is possible because R134a is largely unregulated even though it's against the law to vent it to the atmosphere although everybody does

Um, it's what you have to do if you want to ensure the best performance possible... Having air come out the vents at 55-60°F is certainly better than not having A/C at all, but certainly it's not as refreshing as when it blows out at 40-45°F with the fan set to High.

And yes, a lot of technicians likely would do that. They're looking for the quick buck rather than full customer satisfaction in such cases.

It's already known anyway the OP's system has a leak, which the new o-rings & hoses should fix (a leaky compressor usually has an oiliness around it as well (around the shaft seal and/or where parts of the body comes together), so not really hard to identify it as a leak source either).

 

[Denisefwd93]

The OP seems to have a system that is intact just, low on refrigerant. And he apparently had it close to cooling but it wasn't hot outside and he was overly cautious about high pressure, which is understandable.

Silly to rip and replace? Could be, because we basically just rebuilt my own system, so yes it is a good way to go but, it's not cheap even though it's not terribly expensive for a condenser, evaporator, and lines.

Age of the system should not affect its operating temperatures and pressures. The refrigerant metering device and the compressor are the only parts that really make the mechanical difference outside of that it's just fans. refrigerant charge. But we all like new stuff

What I don't like about Automotive air conditioning replacement parts? They don't seem to have a certification or tag saying the parts were pressure/ leak tested approved and or passed.
New, Parts and systems can leak just as bad as old. I'm used to components coming with a holding charge and temporary caps on the ends of the lines. I guess it's not practical in the auto business

 

[4x4junkie]

But at least your new leaky parts would have a warranty so you are protected from being out whatever $$$ you spent on them.


Look, I'm not here to change anyone's mind who apparently has their thought processes cemented in stone, if you or anyone else here wants to cut corners and just dump refrigerant into a leaky system, then that's entirely up to you. I'm here explaining how I did mine and what my experiences have been, because surely some ignoramus will get on here and try to tell me again my thermometer was defective or lying when I took this pic while it was 95° outside:



What that pic shows has never once occurred the many times I've just tried to add refrigerant from a can into an ailing system (on one occasion it did come close, but it didn't last for more than a few months).

I can go out there today (10 years later) and take that exact same pic and it'll probably still be within a few degrees (yes it still blows cold like I remember from the beginning).


.

 

[Denisefwd93]

I've been loving it in my truck, I've been looking for reasons to actually drive it in hot weather now!

4x4 have you ever used any of those so-called "automatic" replacment orifices? Think I'd just go for an expansion valve they work wonderful when they work right.

 

[4x4junkie]

My BII originally had a "Red" fixed orifice, which I kept (no, not that same one lol, but another (new) red fixed orifice).

I did see the variable orifices available, however I read that they trade off some performance at higher speed for a little better cooling at idle or while stopped in traffic. I never really had noticed my Ranger struggle to cool at slow speeds with it's fixed orifice so I just stuck with what works..

 

[Denisefwd93]

I've had my system operating on the red and the blue and I could not see any difference and I'm actually surprised it cools at idle or in stop and go traffic


Ford
Orifice Size

Blue .067"*
Red .062"*
Orange .057"*
Green .052"*
Brown .047"*

My BII originally had a "Red" fixed orifice, which I kept (no, not that same one lol, but another (new) red fixed orifice).

I did see the variable orifices available, however I read that they trade off some performance at higher speed for a little better cooling at idle or while stopped in traffic. I never really had noticed my Ranger struggle to cool at slow speeds with it's fixed orifice so I just stuck with what works..