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Old 05-17-2019, 04:36 PM   #1
Cwazywazy
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Default Something ain't right (AC)

AC was open for a few months (No condenser installed) but recently I put in the condenser and a new drier. Pulled vacuum and it held for days so I tried to fill er up with Envirosafe. Low side took up to 70psi as usual, but the compressor wasn't kicking on. So I tried giving it a little jump to get it going at the drier switch. Compressor kicked on but absolutely nothing happened in terms of pressures.. See video.



So then I cracked open both valves on the AC manifold to let pressures even between high and low to see what would happen. Compressor kicks on by itself now but the pressures don't move a single PSI when it does.



I have no idea what's going on.. All the AC parts I'm using were working perfectly last year.

EDIT: I thought maybe the expansion valve was stuck open but if that was the case I think the high and low side would've evened out when I put AC juice into the low side. I replaced the valve like 2 years ago IIRC. If it was stuck closed I think the compressor would suck everything out of the low side and pump it into the high.. I dunno. Help.
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Old 05-17-2019, 07:34 PM   #2
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Being from CT You probably never heard of a dirt dobber.

They are little black wasp that kill spiders and put them and an egg and seal it with mud in any and all small orifices that they can find. They come in various sizes and seek various sized holes. Someone from the South would never leave anything like an AC system open for even a day in the summer.

The set of small sockets on the work bench has to be cleaned out often.

If I make the assumption that the compressor clutch is engaged then something is blocking the system between the low charge port and the compressor high side port. That would be the compressor.
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Old 05-17-2019, 08:57 PM   #3
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I had the lines duct taped pretty well so I doubt anything other than moisture got into the system.

Also I gave the expansion valve a few tappy tap taps and then the system drank a full charge of Envirosafe. (14oz.) So, percussive maintenance for the win.

EDIT: I spoke too soon. One of the connections on the compressor worked loose and blew the charge while driving. Wasn't even running the AC.

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Old 05-17-2019, 10:08 PM   #4
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How much refrigerant did you put into the system? Is it possible that the refrigerant never actually went into the system and just stayed in the low side hose? I would verify the connections are working on the a/c manifold set. Ideally you want to charge through the high side hose with the engine off and use a scale to verify the amount of refrigerant you added. This way you can verify that the expansion valve is not restricted, because the low side psi will equalize with the high side as you charge the system.
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Old 05-17-2019, 10:38 PM   #5
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I gave it 14 oz of the Envirosafe stuff. 6oz Envirosafe = 16oz r134a. I don't remember what a 240 AC system takes but I did some napkin math and 14.1oz is exactly how much Envirosafe it gets. A bit over 2 cans worth. I used a kitchen scale to measure it out. Vent temps got down to about 45. I think I'm gonna open up the expansion valve and check all the other fittings before I try charging it again.
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Old 05-18-2019, 01:42 PM   #6
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A 240 takes 1.63 lbs of R134.

I looked at the Envirosafe site and can't find any info on how much Envirosafe equals how much R134. Where do you find that?

Duracool has such as chart below, but in the Envirosafe site FAQ's I find:
Q: How do I know how much refrigerant I need in my vehicle?
A: Usually you will find this information on the label by the engine, inside one of the doors, in the vehicles manual, or contact your dealer for this information.

No help at all.
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Old 05-18-2019, 01:49 PM   #7
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Right on the can it says equal to 16oz of R134.



I took out the expansion valve, cleaned it, and went from 3 turns out to 4.5. It's all back together and I'm about to pull vacuum on the system.
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Old 05-18-2019, 06:28 PM   #8
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Vent temps are the same as before with expansion valve adjustment. 45 at the vents. Not what I was hoping for but good enough that I'm not gonna dick with it. Compressor started cycling like it should instead of running all the time too.
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Old 05-18-2019, 07:20 PM   #9
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From memory, the 2 series from 91 -> have an orifice tube for expansion; earlier have the TXV. Which year do you have?

~70 psi isn't a bad starting point for a system which is OFF; you need to find refrigeration tables for this enviro stuff you have substituted for R134a. With known ambient temps you can find your system pressures when the compressor is functioning. I haven't worked much with the earlier systems (TXV), but my son just refitted his 89 245 and is getting respectable cooling with a new Chinese condenser and a pair of new hoses.

If you can't trust your gauges for charge, then trust temperatures. You want the refrigerant temps just slightly superheated leaving your evaporator (in the cabin). Feel the pair of lines when the system is cycling and the returning line should be just a little warmer than the one behind the TXV valve (if you can get to it, in the dash on the 2 series).

I'd offer more but am not sure which vehicle model you are working on. Your receiver/dryer near the firewall should break a nice sweat on moist days and that is where you should be able to compare the temps between entering/returning from the evaporator (in the cabin). Remember, the goal is complete "phase change" in the evaporator, boiling all your refrigerant and then just gaining a bit more energy so that you don't send liquid back to your compressor.
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Old 05-18-2019, 07:37 PM   #10
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Oh, this is an 82 with the compressor out of an 86. TXV system. Drier and high pressure line going into the firewall are a bit warm to the touch and return line is a little cold. I don't like wasting refrigerant and since 45 at the vents is realistically fine I think I'm just gonna leave it be, but I plan on fixing the AC in my new 88 240 and I'd like to get it as cold as I can, obviously. I already tested the electric part but I haven't checked for leaks yet.
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Old 05-18-2019, 07:58 PM   #11
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Unless you feel certain that your heater valve is completely closing (not always the case) you might clamp off a heater hose to see if that lowers your vent temp.
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Old 05-18-2019, 09:45 PM   #12
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Quote:
Originally Posted by dbarton View Post
Unless you feel certain that your heater valve is completely closing (not always the case) you might clamp off a heater hose to see if that lowers your vent temp.
After driving with ac off and fan on low the vent-o-meter reads a hair over 70 with outside temp being 63. Heater valve is probably open a tiny bit.
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