Why is this hissing?

[BTR]

2000 Explorer XLT 2WD 4.0L SOHC JOB1 Engine 140,000 miles.

In the attached photo, see the red arrow. I every-so-slightly --- just-a-teeny-weeny- bit --- unscrewed the black, plastic cap. I immediately heard a hissing sound, i.e., gas was escaping. I screwed the cap back on --- the hissing stopped.

My best-educated-guess is that this is the high-pressure refrigerant line for the A/C. I'm wondering... does the plastic cap seal this shut... or is there a Schrader valve underneath the plastic cap, and it seals it shut... or is there some other type of closure underneath the plastic cap? Thanks for your help.

 

[410Fortune]

You are correct! AC high pressure port

your ac valve is leaking under the cap, very common
Sucks because to fix you have to evacuate the system

Sometimes you can depress it really quickly and it will seal back up....meaning it maybe stuck open by a small piece of debris and by quickly pressing it down and letting some gas escape you may clear the debris

I have found MANY slow AC system leaks come from the high pressure or low pressure ports....
the cap will only slow it down, you need to get that fixed or one day you will have no AC and all the refrigerant will escape into the atmosphere

 

[BTR]

@410Fortune - Thanks. Just to clarify, is it a Schrader valve?

 

[darkwish]

There is a tool that can replace shrader valves without letting all the gas out.
Here is a set on amazon.
https://www.amazon.com/dp/B07QVF2V2...olid=2UL12YRLZ6X97&psc=1&ref_=lv_ov_lig_dp_it

 

[BTR]

There is a tool that can replace shrader valves without letting all the gas out.
Here is a set on amazon.
Amazon.com: Lichamp Automotive AC R134A R1234YF Valve Core Remover and Installer Tool Set, for Standard and JRA Valve Core Couplers: Automotive

Yes, that's correct. That's what I plan to use, i.e., a Schrader valve replacement tool. Does anyone know where I can get the refrigerant charging chart for a 2000 Explorer 4.0L SOHC?

 

[RickOTR]

https://www.autozone.com/diy/climate-control/how-to-recharge-car-ac

 

[BTR]

If I end up having to evacuate the system and then fill it to factory spec (per the decal under the hood), how do I get all of the old PAG oil out?

 

[koda2000]

It is pretty common for A/C system ports to leak refrigerant from a Schrader valve. As said a tiny bit of dirt can get into the valves seal, preventing it from closing all the way. For this reason the plastic caps covering the valves are quite robust and have a thick seal inside them. The leak was there before you removed the cap. You probably could have reinstalled the cap tightly and not worried about it.

You don't have to get all the PAG oil out. Most of it will come out with the refrigerant when the system is evacuated. Depending on how much comes out you can guess-timate how much to reinstall with the proper amount of refrigerant. A little extra PAG oil wont hurt the system. Better a little too much than too little. Go with what is suggested by the shop refilling the system. A completely empty new system (no oil) takes around 9 oz of PAG 46 and around 30 oz of refrigerant (there should be a tag under the hood telling you how much is recommended).

The right way to add/replace refrigerant to an A/C system is to evacuate the system first. You can try adding a bit of refrigerant to a charged system which you suspect is low, but that's a guessing game and too much pressure can blow lines. If you're planning to just add refrigerant it's best to use a A/C gauge manifold to monitor the HI and LO pressures. You also have to take into account the ambient temp and humidity.

 

[BTR]

@koda2000 Thanks. Just to confirm, for a 2000 Explorer 4.0L SOHC, does it use PAG 46? Or does it use PAG 100? Where can I find the temperature/pressure charging chart? I prefer to replace the Schrader valve (using a valve replacement tool) and then charge to temp/pressure using a manifold gauge set. Also, does it have a Standard valve core, or a JRA valve core (both high and low)?

 

[fast_dave]

There is a tool that can replace shrader valves without letting all the gas out.
Here is a set on amazon.
Amazon.com: Lichamp Automotive AC R134A R1234YF Valve Core Remover and Installer Tool Set, for Standard and JRA Valve Core Couplers: Automotive

@darkwish

+10 Find!

 

[XLTrunner]

Don't mean to hijack this thread with another question but, I think the answer could benefit the OP as well...so, here goes. If a person is to top off the refrigerant without evacuating the system first while using manifold gauges, why wouldn't you want to purge the air out of the blue (low pressure) hose by unscrewing the hose fitting slightly at the manifold while slowly opening the valve at the LP port..then re-tightening the manifold hose fitting? I get the need to do that with the yellow hose when adding refrigerant to purge the air inside the hose, but what happens to the air that's inside the blue hose if not purged? It has to go somewhere and seems to me it would get sucked back into the system once the refrigerant started to flow. Not one of the YouTube videos I've watched addresses this.

 

[BTR]

Don't mean to hijack this thread with another question but, I think the answer could benefit the OP as well...so, here goes. If a person is to top off the refrigerant without evacuating the system first while using manifold gauges, why wouldn't you want to purge the air out of the blue (low pressure) hose by unscrewing the hose fitting slightly at the manifold while slowly opening the valve at the LP port..then re-tightening the manifold hose fitting? I get the need to do that with the yellow hose when adding refrigerant to purge the air inside the hose, but what happens to the air that's inside the blue hose if not purged? It has to go somewhere and seems to me it would get sucked back into the system once the refrigerant started to flow. Not one of the YouTube videos I've watched addresses this.

@XLTrunner - You are correct. However, there's one caveat. Your scenario assumes that there is in fact pressure at the low-side charging port. If pressure exists at the low-side charging port, then yes, it's good technique to purge air from the blue hose. If no pressure exists at the low-side charging port, then it's (almost) a given that the system must be evacuated, pumped down, and charged from scratch.

 

[RickOTR]

PAG 46 for the Explorer. That what I use and is recommended by Ford. The Temp chart is in the link I gave you.

 

[BTR]

PAG 46 for the Explorer. That what I use and is recommended by Ford. The Temp chart is in the link I gave you.

@RickOTR - Yes, I saw the charging chart at the link you shared. However, I'm looking for the chart that's specifically for the 2000 Explorer 4.0L SOHC.

 

[RickOTR]

There is no specific chart for the Explorer. It's the same for all manufactures. Here's a link for the chart off of this forum.

AC Chart wanted

Looking for the Pressure/Temperature chart for a 94 sport with front AC only. System is factory r-134a and my low side readings are lower than the standard chart pressures. I have the grey orifice and it had a grey one when I purchased the truck. I know some Explorers used a red orifice and...

www.explorerforum.com

 

[BTR]

At what RPM should the engine be running when measuring the low- and high-side pressures? I've read that it should be at a steady 1500 RPM. Is this correct?

 

[sandsprayer]

I too have experienced a hissing sound. Upon opening the hood out jumped a bobcat, it wun't very happy.
Scared me!