A/C leaking Freon when compressor engaged

Tiny
VF750RIDER
  • MEMBER
  • 1998 FORD EXPLORER
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 137,000 MILES
A/C expels Freon (I assume) when compressor engaged, through a small brass fitting on the manifold hose block connected to compressor. Clutch only engages for maybe 2 seconds about every 30 seconds. Couldn't see the gas expel unless have the RPM's up, then see white fog expelled like a nitrous purge. Every A/C part was just replaced with new parts, including hoses. System was vacuumed for an hour, small amount of oil added (because some ran out when removed plug and installed manifold hose), and freon added to spec. A/C worked and blew cool air a couple times for a week (wasn't quite warm enough to run A/C much). Now no cool air, and this symptom. I read possible restriction somewhere, orifice tube is only place I can think. Any other areas or tests to run?
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Sunday, April 11th, 2021 AT 11:31 AM

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Tiny
KASEKENNY
  • EXPERT
It sounds like you just have a leak at this place. The fact that you can see it means that is where we need to start. This is a sealed system so even when there is a restriction it should not leak.

When the system is completely full, what are the pressures?

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Can you get a picture of this fitting that is leaking as well?

I would not worry about a restriction until we fix that leak. Then we can check pressures again and find out if the system is operating.

However, the fact that it only runs for a couple seconds is another sign of low freon so again, we need to start with this and go from there. Thanks
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Monday, April 12th, 2021 AT 6:02 PM
Tiny
VF750RIDER
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Picture attached. Can clearly see that this is a valve (brass colored) on the aluminum manifold hose block that is attached to rear of compressor. The compressor engaged as it should when initially charged. But we never ran engine above idle with hood up, so we never saw this "purge" on first day. It's my belief that after a few days of light use, enough Freon has purged out where now the compressor only engages for a couple seconds. A few more cycles and I expect it won't engage at all anymore.
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Monday, April 12th, 2021 AT 7:08 PM
Tiny
VF750RIDER
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Also attached a short video of it purging. Compressor only engages for a split second every few seconds. When you see the short purge, that is when compressor is engaged. Holding accelerator at about 2,500 RPMs.
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Monday, April 12th, 2021 AT 7:11 PM
Tiny
KASEKENNY
  • EXPERT
Oh. Got it. That really helps. This is the pressure relief valve. So you do have a pressure issue which is a possible restriction but we need to start from the beginning.

You are correct that it is leaking over time but that is due to the compressor either not shutting off and the pressure keeps building until the PCM cuts it off or the freon drops to the low level where it just short cycles.

This relief valve vents at 470-600 PSI so we need to fill the system to the proper charge and then get the pressures.

We need the pressures with the system off and then with it on. Watch the compressor clutch and see if it cycles. It should shut off and then turn back on ever 20 seconds or so. If it doesn't shut off, you need to turn the system off once the high side pressure reaches 375 PSI. This will prevent you from loosing more freon.

Let me know if you have questions. You can get a gauge set from a local parts store. Most of them will rent them to you pretty cheap.
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Monday, April 12th, 2021 AT 7:18 PM
Tiny
VF750RIDER
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My brother has gauges, can look at pressures again this weekend. I can tell you that when we initially filled system everything on the gauges looked within range at the time, and the compressor clutch cycled normally (every 20 seconds or so).

One thing I do remember we thought was odd at the time. Was how quiet the compressor was when clutch was engaged. Maybe just because it was new and was still getting pressurized as we waited for the freon to enter.

Evaporator and condenser were both pressurized and capped from manufacturer so you were assured of no leaks at install, so I can't see where there would be restriction inside either of them. That leaves drier/accumulator, compressor, and orifice tube as possible culprits. Since orifice tube is only $3.00, but plays such a big role in reducing pressures between condenser and evaporator, that is my #1 suspect.

I figured since system virtually empty as it sits now (in theory), that I might as well take $3 gamble and install another orifice tube before recharging. If I just recharge, I'll just get same result and lose more Freon.
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Tuesday, April 13th, 2021 AT 1:45 AM
Tiny
KASEKENNY
  • EXPERT
Agreed. I understand if you want to put that in it but what we need to be aware of is if this is a new compressor, what was the compressor replaced for?

If this came apart and put metal through the system then we could be dealing with more issues. So if you put the orifice in it now and then charge it and check the pressure. However this time, let's leave the gauges on it until we get the pop off valve acting up again. If the pressure is normal then you have a faulty valve.

However, once this starts, you can just cut the system off and not loose much freon at all. Either way we will most likely need to recover the freon again to make a possible repair.

Again if the orifice fixes it then none of this matters.

Let us know what you find. Thanks
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Tuesday, April 13th, 2021 AT 7:39 PM
Tiny
VF750RIDER
  • MEMBER
Okay, so connected gauges and pressures were all off - high side was only 100, low side was 80 with compressor off, and reduced to 35 as compressor ran. This lead us to think definite restriction somewhere. My guess was orifice tube since I had replaced all parts including hoses and I could not remember the orifice tube that I installed being red, I remembered it being darker. Captured Freon from system and removed orifice instantly saw metal shavings on orifice tube screen and noticed tube was purple not red. Red =.062in. Purple slightly smaller at.0605in. Metal shavings indicates that the brand new compressor wreaked itself on initial run. So will replace compressor again and back flush all other components.
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Saturday, April 17th, 2021 AT 7:05 PM
Tiny
KASEKENNY
  • EXPERT
Wow. Great update and analysis. Back flushing will work for all components except the accumulator. These will not flush so I would replace this anytime you have metal in the system even if it was new.

Below is the process for this if you need it. Thanks again for this information. It will surely help others in the future. Thanks
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Sunday, April 18th, 2021 AT 7:41 AM
Tiny
VF750RIDER
  • MEMBER
Yes, I did file warranty claim on accumulator and ordered another new one. I think the return process for the compressor automatically requested that a new orifice tube and accumulator had to be ordered to get refund on the compressor. I will update when we try again! Lol
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Sunday, April 18th, 2021 AT 10:12 AM
Tiny
KASEKENNY
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Okay. Sounds great. Let us know how it turns out (again) :)

Thanks for the update.
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Sunday, April 18th, 2021 AT 6:39 PM
Tiny
VF750RIDER
  • MEMBER
Awaiting new condenser, but received replacement compressor and drier. These compressors have a big sticker that states "contains 7oz of PAG46 oil, more needed if have rear AC" . My 1998 Explorer calls for 7oz of oil in system, so I assumed all was well. I opened new compressor today dumped and measured oil - I got almost 3oz after 20 minutes of draining and rotating unit to pump oil out. No wonder the last one imploded! A mechanic friend suggested that I add some oil to the other components, that the Freon actually kind of "rides" on the oil and it's good to have a bit throughout the system. So this time I will personally add 1oz to condenser, 1oz to evaporator, maybe a tad into the manifold lines, and remainder of 7oz into compressor. Maybe will get to reinstall this coming weekend.
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Wednesday, April 21st, 2021 AT 4:46 PM
Tiny
KASEKENNY
  • EXPERT
Sounds like your friend is or was trained by an old school tech. As long as the right amount of oil is in the system, it doesn't matter where it goes however, most of it should be in the compressor. However, you are correct as that is why it failed.

Lastly, the manual says 9 oz so if that compressor comes with 7 then just put 2 more in some of the other components.
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Thursday, April 22nd, 2021 AT 7:37 PM
Tiny
VF750RIDER
  • MEMBER
Replacement parts all finally arrived and installed. Backflushed the lines and evaporator with AC solvent flush and air. Filled compressor with most of oil (added some to condenser and evaporator), connected everything, vacuumed, added freon, all was looking good, then. Blow-off valve started up again! High pressure not even up to 200 PSI yet.

So we figured that valve must be bad - it's on the manifold hose block so it wasn't replaced with compressor. Evacuated Freon and dug the original valve out of trash swapped. Repeated everything and looks like we got A/C now!

Turns out that valve was adjustable (could see the tiny allen wrench shape in it after removal) - it was not tightened down as much as should have been. No way for us to know how tight is correct so the original factory valve will have to do. As usual, $100's of trouble over a 20 cent part that has info available on and you can't even buy individually.

Thanks for the help, and I hope someone else finds this story helpful.
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Saturday, May 15th, 2021 AT 4:41 PM
Tiny
KASEKENNY
  • EXPERT
Unbelievable. That is normally the case that the cheap part was the issue. That is great info because I didn't know they are adjustable. I am sure others will benefit from this as it is common issue.

Thanks for using 2CarPros. Please come back in the future. Thanks
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Sunday, May 16th, 2021 AT 5:19 PM

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