Any A/C gurus here? I’m stumped

any4xx

any4xx

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New to me ‘04 Unlimited. A/C wasn’t working when I got it about a month ago. Service records show a new condenser in 2014 and a new evaporator in 2017. A few weeks ago I put a new Denso compressor in it and everything held vacuum. I charged the system and it blew cold. A week or so later I drove it and no more cold air. I’ve been busy with other projects so haven’t been able to get back to it until today.

I discovered that there was very little charge left in the system. I pulled vacuum and everything held just fine again. I pressurized the system to 90 PSI and let it sit for a half hour. It held pressure. I went ahead and pulled the orifice tube. It wasn’t clogged but did have a few small metal shavings on the screen. I’m inclined to replace everything except the evaporator, but instead flush that out because I’m not wanting to go dash-out if I can avoid it.

So first… how can the charge leak out if the system holds both vacuum and pressure? Have you ever had a compressor that leaks while running but not while stationary? I can’t really think of any other scenarios to explain this.

Help?

Thanks in advance for any help.

Tom.
 
JKP said:
Refill it with 134 and dye to find the leak.
Click to expand...

Sadly, when I initially added PAG-46 it had dye in it. No traces of any leaks seen. I should have added that in my initial post. So it’s obviously leaking. But no traces of any leaking. This is weird.
 
JKP said:
I'm guessing you didn't check the AC drain for dye.
Click to expand...

But again. Everything holds vacuum AND pressure while stationary. The only thing that I can think of is the compressor itself is somehow leaking while running but not while disengaged. But why no UV traces???
 
There's dye and oil somewhere.

The compressor would be slinging it if it comes out the front seal.

Have you let it sit with vacuum overnight?

Any film on the windshield?
 
Nothing found anywhere. BUT…. I just disconnected the lines from the accumulator, as I was going to blow air through everything to check for obstructions. The system was completely depressurized. When I pulled the inlet tube off of it green PAG oil EXPLODED all over my engine compartment. So there’s definitely a clog in the system. Still no clue how I lost charge without any oil tracing, but something is definitely screwy. I feel better about the compressor being okay but I’m definitely replacing the accumulator and flushing the lines, evaporator, and condenser before trying to charge it again.
 
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I’m going to say your office tube is clogged, they don’t have a traditional line filter. The system uses an orifice tube (acting as the liquid metering device/strainer screen) located inside the liquid line near the passenger-side firewall/condenser area, and an accumulator on the low side that contains a desiccant bag to trap moisture.
 
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Jhighers said:
I’m going to say your orifice tube is clogged, they don’t have a traditional line filter. The system uses an orifice tube located inside the liquid line near the passenger-side firewall/condenser area, and an accumulator on the low side that contains a desiccant bag to trap moisture.
Click to expand...
 
Jhighers said:
I’m going to say your office tube is clogged, they don’t have a traditional line filter. The system uses an orifice tube (acting as the liquid metering device/strainer screen) located inside the liquid line near the passenger-side firewall/condenser area, and an accumulator on the low side that contains a desiccant bag to trap moisture.
Click to expand...

Orifice tube had a few shavings in it but was relatively clean. Actually a lot cleaner than some I’ve removed from working systems. I replaced it earlier today anyway. It appears that my accumulator is completely clogged up though. Tomorrow morning at 0730 the O-O-O store will have my replacement for me. All the lines as well as the evaporator and condenser are completely clear.

I still don’t know how I lost charge without any dye tracing or why the charge was low while the system would hold both vacuum and pressure. Hence my original question. But tomorrow I’ll zip it back together with a new accumulator and fresh PAG-46 and charge it up again. And I hope to remain completely mystified as it works flawlessly. Hoping a lot, actually.
 
Daryl said:
The most common place for the refrigerant to leak after servicing is the service valves where the gauges connect. Especially if the service valve caps were missing.
Click to expand...

Actually, both are sealing well. Whenever I charge a system I give both a quick pop to ensure they’re sealed. I’ve actually got a whole kit full of replacement valves for these stupid leak-prone things. Sadly, this time neither of those was the easy answer.
 
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JKP said:
I'd put dye in as well, just in case.
Click to expand...

Absolutely. Every time. For the record, it looks like the accumulator is the one remaining original part from 2004. If it isn’t the cure I don’t feel like it’s wasted money.
 
Good choice to replace the accumulator. In my research before replacing my entire AC system, it was recommended that the accumulator be replaced anytime a major AC repair is performed.

Oil gathers in the accumulator and compressor, so after multiple charges, you can have too much PAG in the system without knowing it.
 
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LJBean said:
Good choice to replace the accumulator. In my research before replacing my entire AC system, it was recommended that the accumulator be replaced anytime a major AC repair is performed.

Oil gathers in the accumulator and compressor, so after multiple charges, you can have too much PAG in the system without knowing it.
Click to expand...
Since this looks like the only part that has never been replaced who knows how much oil & detritus it has “accumulated.”
 
Evaporator. Poop!

Even though there’s no trace of dye at the housing drain I believe I’ve narrowed it to being an evaporator leak. Remember: I replaced the compressor just a few weeks ago and the system held vacuum just fine. And there’s a receipt showing the evaporator was replaced 9 years ago. But today I replaced the accumulator and buttoned everything back together. It wouldn’t hold vacuum. I pressurized the system to 100 PSI and went crazy with the soapy water. No bubbles to be found anywhere, but the pressure was dropping when the pressure source was removed.

I decided to disconnect the evaporator lines and make use of my collection of rubber corks to vacuum everything except the evaporator. An hour later I’m holding vacuum.

I’m somewhat relieved to have finally found the problem.

I’m still confused as to why it held vacuum a few weeks ago but lost pressure in just a few days with no dye escaping the system. My GUESS is that the leak is near the top where PAG oil & dye wasn’t accumulating and that the evaporator was iffy when I vacuumed and charged it. The strain of actually having to do its job caused the slow leak. A “perfect” failure?

Now I’m dreading the dash-out adventure that is to follow. I’m not sure if I’m digging into that today or tomorrow. Luckily I’ve got other cars to drive so I’m not in any hurry.

Thank all of you who took the time to respond.
 
Last edited:
I was dreading the "dash-out adventure" as well, but there are a couple of decent You Tube vids that provide good info on how to do it without removing the steering column, and the process wasn't as difficult as feared. Change out your heater core while you're in there!
 
any4xx said:
Evaporator. Poop!

Even though there’s no trace of dye at the housing drain I believe I’ve narrowed it to being an evaporator leak. Remember: I replaced the compressor just a few weeks ago and the system held vacuum just fine. And there’s a receipt showing the evaporator was replaced 9 years ago. But today I replaced the accumulator and buttoned everything back together. It wouldn’t hold vacuum. I pressurized the system to 10 PSI and went crazy with the soapy water. No bubbles to be found anywhere, but the pressure was dropping when the pressure source was removed.

I decided to disconnect the evaporator lines and make use of my collection of rubber corks to vacuum everything except the evaporator. An hour later I’m holding vacuum.

I’m somewhat relieved to have finally found the problem.

I’m still confused as to why it held vacuum a few weeks ago but lost pressure in just a few days with no dye escaping the system. My GUESS is that the leak is near the top where PAG oil & dye wasn’t accumulating and that the evaporator was iffy when I vacuumed and charged it. The strain of actually having to do its job caused the slow leak. A “perfect” failure?

Now I’m dreading the dash-out adventure that is to follow. I’m not sure if I’m digging into that today or tomorrow. Luckily I’ve got other cars to drive so I’m not in any hurry.

Thank all of you who took the time to respond.
Click to expand...

Ya that’s a bit odd
 

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