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As part of my other tasks to get this Intrepid ready to handover to my son and daughter-in-law, I need to re-charge the A/C on our 2003 Dodge Intrepid (2.7L).

I had to replace a bad line on the low pressure side (pics are in another of my posts - I got lucky and found one of the lines still available - it is NLA on the mopar parts websites). I also replaced the receiver/dryer.

I have an A/C Manifold gauge set, a good 4cfm vacuum pump, and the refrigerant. I've also watched a lot of detailed videos on pulling a vacuum properly, and then using teh manifold gauges and charging the system. I have one of the harbor freight manifold gauge sets. The only thing I don't like about it is that it doesn't include a purge valve on the aux port line, so I fashioned one from appropriate bits at the hardware store. I figure, why waste all the time pulling the vacuum, if you can't purge the aux line as you're adding refrigerant...if you don't purge it, you'll just pull air from the aux line into the system.

Anyway, I pulled a vacuum on the system for about 30min, then I closed it up and watched for any leaks. An hour later and the vacuum was still being held, so no leaks. I then pulled a vacuum again for another 45min. THEN, I tried to add the refrigerant. I purged the line and added refrigerant. The low-side pressure came up, but I never heard the AC compressor engage, and the high side never started reading a pressure (it still shows a vacuum). I ran the car for a while, but no change. The system took about a 1/3 - 1/2 can of refrigerant. The static pressure on the system is reading about 30psi on the low side, now.

So, next I checked: AC Clutch Relay feed Fuse - Fuse B (40A) in the Power Distribution Center under the hood. It measured good, and I measured 12V at the terminal in the PDC, so the power is there. Then, I checked Fuse 21 in the Driver's side fuse panel (10A) which is for the AC Clutch Relay enable circuit: same thing...the fuse measured fine, and there was voltage at the fuse.

I'm stuck at what to check next. Maybe the low pressure switch? Or manually jumper the AC clutch on?

I've tackled just about everything on a car to repair, but A/C has always had me stymied. I am determined to figure this one out and get past the last sticking point in my repair knowledge.

Any advice is appreciated.
 

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Try injecting refrigerant into the high side to get pressure to the pressure transducer and to equalize pressure across the expansion valve (of course you know not to have the high side pressure ported to your can once the compressor is running). Short of that, you could jumper the clutch on until pressure is throughout the system.

Got PAG46 oil?
 

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Discussion Starter #3
I do not have PAG46 oil. I guess I'm wrong in assuming that since I am did not replace any major components, and that I pulled the AC clutch relay right after replacing the line (there was still refrigerant leaking from the system then), that I would not have to add additional oil? All that was replaced was the section of line with the low-side port (it corroded through at the rubber-wrapped clamp to the body) and the receiver drier - the ompressor has not been run since those were replaced, and the system was sealed except for when the line and the drier were replaced. The vacuum was pulled as soon as the new drier was installed.

Also, I did run the non-DRB3 HVAC diagnostic - the cluster reported AC 00 - no errors.

I can try your suggestion to put some pressure in the high side tomorrow. And, as you caution, I will make sure to turn off the high side valve on the gauge set before starting the car and switching to charge on the low side again. Jumpering the clutch makes sense, too, if the high side pre-charge isn't enough to get it to kick on.
 

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i got caught once with a valve core in the end of the guage line.
the vacuum pulls through, but the pressure pushes the wrong way.
so you only fill your low side line on the guages.
or, you forgot to remove a plug on your replacement line.
 

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Discussion Starter #6 (Edited)
@peva , I added some refrigerant through the high side late last night, and then let everything sit until the morning. There was no leakdown. After making sure the high side valve was closed on the manifold gauges, I started the car and turned on the AC - and the AC clutch engaged! So at least I know that is working!

But, the system seems to be slow to take refrigerant. I'm attaching the readings from my manifold gauges:

Here is the static pressure (engine off):


And then these are the readings with the engine running:




When the engine is running and the AC is on, I hear the sound of gas movement in the interior (likely the refrigerant moving through the evaporator coil?), and when I turn the AC off is slowly stops. The air is not blowing cold, yet. The high side pipe at the port is warm to the touch, and the low side port is cool to the touch. The pressures hold, so it's not a leak, but it seems...strained. I hope my description helps convey what I'm hearing. Thanks for the help so far!

@yevrah , the pipe I replaced was the section with the low side port, so it's a brand new valve on there. That doesn't mean there couldn't be fill problems, though. I did remove the plugs when I installed the pipe, and the receiver/drier had a sticker covering the ports, so that was removed before installation. I would prefer to not to remove that low-side pipe to double-check that it's not plugged, but that may be a next step (and then draw a vacuum again, etc.).
 

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Discussion Starter #7
Here is a video that captures the noise in the interior when the A/C is running.

 

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When you have the hood open and stand looking at the compressor, is that noise coming directly from the compressor, or is it vapor (air or refrigerant) flow noise emanating from inside the dash? It's hard to tell if it is more a mechanical or gaseous flow noise.
 

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@peva , there is another post I have in this thread, but it is waiting for moderator approval for some reason. I have pictures of the pressure readings I am getting in there. Hopefully that will post, soon.

The noise is a gas-movement noise only, and only heard in the interior. There are no unusual noises in the engine compartment, and the AC clutch is engaging and disengaging correctly as I turn the AC on or off, but it is not cycling on it's own. the noise stops when I turn the AC off, and resumes when I select the AC on.

The static pressure (engine off) is reading about 60psi on both the low and high side when stabilzed, btw.
 

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Maybe my other post (still not cleared) had images that were too large or something. I re-sized a couple and posted them here.

Pressures with the engine running and AC On


Pressures with the engine running and AC Off


Pressures with the engine off and all the valves closed
 

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And here is the content of my other "not cleared yet" post, without the pictures...

....

@peva , I added some refrigerant through the high side late last night, and then let everything sit until the morning. There was no leakdown. After making sure the high side valve was closed on the manifold gauges, I started the car and turned on the AC - and the AC clutch engaged! So at least I know that is working!

But, the system seems to be slow to take refrigerant. I'm attaching the readings from my manifold gauges:

Here is the static pressure (engine off):
<snipped>

And then these are the readings with the engine running:
<snipped>

When the engine is running and the AC is on, I hear the sound of gas movement in the interior (likely the refrigerant moving through the evaporator coil?), and when I turn the AC off is slowly stops. The air is not blowing cold, yet. The high side pipe at the port is warm to the touch, and the low side port is cool to the touch. The pressures hold, so it's not a leak, but it seems...strained. I hope my description helps convey what I'm hearing. Thanks for the help so far!

@yevrah , the pipe I replaced was the section with the low side port, so it's a brand new valve on there. That doesn't mean there couldn't be fill problems, though. I did remove the plugs when I installed the pipe, and the receiver/drier had a sticker covering the ports, so that was removed before installation. I would prefer to not to remove that low-side pipe to double-check that it's not plugged, but that may be a next step (and then draw a vacuum again, etc.).
 

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make sure your low side hose doesn't have valve core in the end.
it's unusual you're low pressure doesn't move.
 

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Discussion Starter #14
@yevrah , so this is inside the blue quick-disconnect coupling? I agree - it seems like the system isn't taking refrigerant, so some sort of flow problem. Although the high side seemed to take input when I used @peva 's suggestion to get the compressor running.
 

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yes, it's on the hose end.
it would allow pressure in, but not out.
something is not right on the low side and it's something i have come across before.
can't say it's your particular problem, but it looks it.

and the flow in your evaporatorsounds like the expansion valve is wide open.
should fix when you get enough in it.
 

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@yevrah , I removed all the manifold hoses this morning and used some low pressure from my air compressor to pass air through each of them in both directions. There were no flow restrictions. The ends of the hoses all looked the same (see pic below).


So, my next step will be to re-check that low-side line that was replaced. Oh, and I'll pick up some PAG46 oil, as @peva recommended, too.
 

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I think I've got it!! It seems to be a bad coupling for the low-side connection!



The right-angle coupling on the right is the problem. When connected to the line, no air passes through the coupling into the hose. By the looks of it, the center pin in the coupling that opens the Schrader valve in the line is too short, so the valve doesn't open and the refrigerant can't flow! If I press down on the coupling, it moves about 1/16" and then I can pass air through the coupling into the line.

With the straight coupling, the Schrader valve completely opens and there is flow!



So, in the end the right-angle coupler is bad. I am pulling a vacuum in the system again now. A little later this afternoon I will attempt charging the system again and we'll see what happens! Fingers crossed! o_O;)
 

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good you found the blockage on the low side.
now you can draw in enough on the low side.
same problem i had, different cause.
should have a better charging session this time around.
 

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This repair is complete - cold air is again happily blowing out of the vents of this car in time for the hot days of Summer!

In all my automotive repairs, I never was successful with A/C system repairs. Those were ones where I either gave up (my first car...I removed the system as a weight-savings and fuel-economy "improvement") or I wound up taking it to a shop.

But not this time...I was determined to understand how the system works, how to diagnose and fix it, and how to re-charge the system with refrigerant!

Thanks to your help here (@peva and @yevrah) and some good videos on YouTube I studied (particularly this one https://www.youtube.com/watch?v=BXTZURC5iQ0 , and this one https://www.youtube.com/watch?v=Pdq8JAlct6s ), I was able to finish the repair of the A/C on our Intrepid!

The issue with the Intrepid was a corroded and leaky low-side A/C line (previously replaced at the time of a transmission repair about a month and a half ago - also documented here in the forum).

That was replaced, along with the receiver/drier.

After diagnosing the manifold gauge set and replaced line, I found a faulty low-side coupler - the post in the coupler (yellow arrow) was too short to engage the pin in the Schrader valve (blue arrow) ! I then pulled a vacuum and charged the system.




And the proof is in the pudding as it were: Before Temp out of the Vent


And the After Temp out of the Vent - success!!


Thanks, again, for all your help! I'm ready to hand this Intrepid off to my son and daughter-in-law now :)
 
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