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07 Grand Caravan (3.3L), 12 Ford Fiesta bAsE
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Discussion Starter · #1 ·
Hi! 2007 Grand Caravan 195,000 miles. The A/C has been slowly getting hotter and hotter, now it's completely hot. A/C Clutch DOES engage when I turn it on. High and Low side pressures are equal while the engine is off, or on with A/C(No fluctuation). Where do I go from here for testing? Thanks for your input
 

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Discussion Starter · #2 ·
Would like to add that the compressor is not making any unusual noises
 

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What is the pressure after it sits for a while. (high and low are equal and when compressor clutch engages no change)What pressure is indicated.
When was the last time the A/C worked?
Perhaps there is no refrigerant in the system, the static pressure should show ambient temperature on T&P chart if there is something other than air in the system.

If you had a clogged expansion valve the pressure would rise until compressor shut off AND it would take a marble to clog an expansion valve like that.
 

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Discussion Starter · #4 ·
What is the pressure after it sits for a while. (high and low are equal and when compressor clutch engages no change)What pressure is indicated.
When was the last time the A/C worked?
Perhaps there is no refrigerant in the system, the static pressure should show ambient temperature on T&P chart if there is something other than air in the system.

If you had a clogged expansion valve the pressure would rise until compressor shut off AND it would take a marble to clog an expansion valve like that.
Last month was the last time it worked pretty well. It's sitting at 100 psi, both high/low with the engine off and cool, or the engine on with a/c.
 

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Discussion Starter · #5 ·
I checked the pressure with a dual gauge from Autozone. Could it be the system just needs to be fully evacuated and recharged(obviously doing a vacuum test while you're at it)? How would there be pressure in the system but no actual refrigerant?
 

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Is it about 87 - 88 degrees F where you are?
If the clutch is engaging and the compressor is turning, I would expect to see the low drop and the high rise.
 

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Discussion Starter · #7 ·
Yep right around there temperature wise. I can visually verify that the clutch is engaging with the A/C switch. Nothing happens to the pressure
 

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Discussion Starter · #9 ·
The last time the A/C was checked was around 3-4 years ago. The pressures were fine and A/C was working perfectly.

This is the chart I had bookmarked from another page on the forum. I don't see why the low side would be the same as the high unless the compressor wasn't compressing?
 

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Yep right around there temperature wise. I can visually verify that the clutch is engaging with the A/C switch. Nothing happens to the pressure
So it appears there is at least a minor amount (and perhaps a full volume) of refrigerant but you are not getting pressure. So I would presume the compressor has been slowly losing efficiency. Perhaps the Expansion valve is not making the restriction to cause the refrigerant to change state (evaporate) and thus not making the cold.\

Good practice is to change the compressor and while you are changing the compressor a new receiver drier and expansion valve.

If you want to just try the expansion valve, no harm other than evacuate and recharge if it doesn't work. Please find a shop that will work with you and have them do the evacuation recovery. I'd hate to think that expressing the refrigerant to the atmosphere is happening... We certainly don't need any of that.
 

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The last time the A/C was checked was around 3-4 years ago. The pressures were fine and A/C was working perfectly.

This is the chart I had bookmarked from another page on the forum. I don't see why the low side would be the same as the high unless the compressor wasn't compressing?
exactly correct OR something is not causing the required restriction and thus no pressure differential...
 

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Discussion Starter · #12 ·
Found a rebuilt compressor for a good price. I'm thinking I'll just order all three new parts you mentioned to get it over with. Evacuate it at the shop, install the parts, and get it filled back up myself.

Would I be able to verify that the expansion valve is defective once I take it off or no?
 

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If you had a clogged expansion valve, the high side pressure would be very high. Higher than high!

If the clutch is engaged, the compressor is turning, and the high and low side pressures are equal, than yes you probably have a bad compressor. Be aware, and depending what happened to the compressor, you may need the system flushed.

On Youtube there are videos on troubleshooting with gauges.
 

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Found a rebuilt compressor for a good price. I'm thinking I'll just order all three new parts you mentioned to get it over with. Evacuate it at the shop, install the parts, and get it filled back up myself.

Would I be able to verify that the expansion valve is defective once I take it off or no?
I suppose there may has to be a way to perform some test to verify operation but I've not got a clue as to how it could be performed or how much effort, cost, etc...

Anytime I change a compressor, at a minimum, I put in an expansion valve and drier. If when disassembling, unless it look like the inside of perfect brand new in anything I can see, FLUSH with SuperCool and DRY shop air.
I try to get a Denso compressor as they are new, OEM (for most), and comparable priced to a good rebuilt or white box new. I'd suggest getting a complete AC seal (oring and gaskets) kit for your vehicle year, make, model (about $12-15 from Amazon) just to have on hand. [buy one that is Free shipping Free returns] just to have it on hand and if you don't open the package you can drop it off at a UPS store (no box, package, envelope or label required) with a QR code on your phone within 30 days for a full refund.

Every five to seven years or anytime the AC system is disassembled or discharged for anymore than a few hours, always replace the desiccant (receiver/dryer of accumulator/drier) Think of it as the little pack of DO NOT EAT in your vitamins. It gets saturated with moisture and/or starts to deteriorate and can cause problems.

DEEP VACUUM is a must.
R134, moisture, and aluminum is a very corrosive combination.
I even break the vacuum with r134 and then evacuate and vacuum again. If you don't deep vacuum it will probably still work for a while but in too short amount of time you may have leaks and when you go to repair it, you'll find that the whole system, parts, hoses, evaporator... everything need to be replaces as it is as if acid had been circulating through the system.

A note on vacuum*
If when you are doing a hold after a vacuum, the vacuum gauge rises it MAY be because there is a leak. Then, maybe not...
*A loss of indicated depth of vacuum may also be some unrecovered refrigerant that is saturated in the oil somewhere and under vacuum it evaporates and expands. Pull a vacuum again and hold. OR wait for some time an see how far the gauge moves and then pull a vacuum, hold, and observe if the gauge stops at a lower mercury value (higher - number) than during the first failed test. (may indicate expanding unrecovered refrigerant) On commercial deep freeze units, sometimes they leave a vacuum pump connected and running for a few days.

Let us know how it goes. We love pictures (worth more than a thousand descriptive words) and if you have any questions, do not hesitate.
Cheers
 

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Discussion Starter · #15 ·
Thanks for the replies guys! I'll update when I get it fixed. It may be a couple months before I get it fixed as the car is not my daily lol
 

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** AutoZone has vacuum pumps available for "Loan a Tool' for up to 90 days for free. Problem there is that I doubt they change the oil and Fresh oil is important to vacuum pump efficiency. YMMV
 

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One more thought...

For a vapor cycle system to build pressure there has to be a restriction (expansion valve) or on some systems they simply use a fixed orifice.
On my 2002 Town and Country, I have two expansion valves front and rear and they are on the same circuit.

If either one of those were to be wide open (no restriction) I can imagine a working compressor circulating refrigerant without building pressure.


Hmm... anyone ever seen this and how to know?
 

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Just one point to watch out for. O'Reilly's also have loaner vacuum pumps and gauges, plus other tools but I believe you only get them for something like 48 hours. After that, they become yours if you don't return them and no, you don't get your money back. I always try to get loaner tools from Autozone or Advance Autos. I've used O'Reilly's only for simple jobs.
 

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GATOR, thanks, as I didn't realize the expansion valve was controlling pressure in the evaporator.
Well, yeah, when it is working as designed, it is lowering the pressure in the evaporator causing the liquid to 'evaporate' at that lower pressure. Done through a restriction of sorts... in this case an expansion valve.

What I was envisioning was that if there was no restriction there would be no pressure change (if either the front or rear expansion valve was open / free flow) and thus little to no pressure differential. Appears to seem like a bad compressor. Fluid, like electricity, is very lazy and will take the path of least resistance.
 
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