Sudden loss of AC performance, Monovalve? - Page 3 - PeachParts Mercedes-Benz Forum

Roncallo · #31 06-05-2020, 09:13 AM

Quote:

Originally Posted by vwnate1

You jogged my memory : Thursday I took my Foster boys all over Los Angeles in my Rich upgraded '82 240D ~ in Woodland Hills it was 103* F and the dash vent read 60* F on the freeway at 60 MPH .

In North Hollywood I encountered 106* F and the dash vent was 58* F .

In Pasadena it was 104*F and the dash vent was 56* F for a short time then crept up to 60 ~ 62* F so I guess I'm good to go, a 40* F TEMPERATURE DROP is good enough for me .

Did you have the windows open when you took those measurements. The chart I posted is for performance results with windows open.

vwnate1 · #32 06-07-2020, 05:04 PM

No Sir ! .

it was too dang hot .

For me, a thirty or forty degree drop is acceptable...

Roncallo · #33 06-08-2020, 01:04 AM

Quote:

Originally Posted by vwnate1

No Sir ! .

it was too dang hot .

For me, a thirty or forty degree drop is acceptable...

I got 30, I'm going to have to live with that, But I got 34 when I closed the windows.

Roncallo · #34 06-13-2020, 05:07 PM

I replaced the expansion valve because I wasn't happy with the low low side pressure

Got everything installed and up an running. Some good news some bad news. On first attempt the copper cone seal was not seated properly and leaked immediately. I was always afraid of this happening and this time it did. I hope I didn't cause a scratch in the sealing surfaces on either the TXV or Evaporator. So far I cant detect anything with my leak detector but I need to get ready top get on the road. I'm leaving for NY in the AM. I replaced the seal and successfully charged 32.5 oz. I didn't want to go any more than that at the moment because that's about 2 oz more than my calculation say is required, but sub cool is still only at 4°. When I get back I may try a bit more.

Ambient temp today was 82°.

High side pressure was 215PSI

Low side pressure was still low at 14PSI

But Duct temp was down to a cool 44°F

I have no idea why the low side will not come up but the high side looks a little better. And I have no idea why its suddenly down to 44° duct temp. I will have a little more testing to do when I get back. I wish I could take the car to NY but there is still a lot of putting back together to do.

vwnate1 · #35 06-13-2020, 11:45 PM

Where does this conical copper washer go ? .

TIA,

Roncallo · #36 06-14-2020, 12:46 AM

Quote:

Originally Posted by vwnate1

Where does this conical copper washer go ? .

TIA,

The conical copper washer is optional and goes between the expansion valve and the evaporator. There is also one for the liquid line to the expansion valve. Mercedes Benz publishes two torques for the expansion valve. You get to apply less torque if you use the washer. Since the expansion valve is in an impossible place to get at and tighten, I elected to use the washers.

Roncallo · #37 06-27-2020, 09:54 PM

First thing to learn in AC school is to check your equipment. I have been chasing a ghost for the last month and this is what I found. The thermometer that reads 42° is about 35 years old. The other two I just got in to replace it. Good news, that means my AC is working really really good.

vwnate1 · #38 06-27-2020, 11:39 PM

Thanx ! .

When I took my Delco factory training there were no digital thermometers that I knew of .

My fingers or face tells me I'm not getting anywhere near 32* F out the dash vents.....

I have a digital laser thermometer, I wonder where I left it ? .

We're going to the Mojave Desert to - morrow, the weather report says there may be clouds ~ I certainly hope so .

Roncallo · #39 06-28-2020, 12:14 PM

Big success on the AC. These taken 81° F ambient 65% RH, using standard test conditions, engine at 2000RPM windows down, blower high, recirc off. Also checked evaporator temp operation. Engine at idle, blower low, windows closed recirc on. Clutch cycled off at 32°F back on at 36° F.

What a difference with new thermometers. 40° Duct temp.

AC is done.

See Finishing Samson for pic.

Finishing Samson the M120 R107

unavita · #40 07-05-2021, 04:48 PM

Quote:

Originally Posted by Diseasel300

The stock 560SL is the one I was suggesting to try the 12V on. If you see a difference, the silver box is probably the source of the leak, not the monovalve cartridge.

Thank you for this.

I read all the comments on p1 and p2, did the test with 12v's and my AC was no longer blowing hot air... but not cold air.

Do you have the name and pn for the "silver box"? Or are you just replacing the capacitors in it- renewing it?

vwnate1 · #41 07-05-2021, 06:38 PM

Good to hear you're satisfied with it, did you take note of the pressures ? .

My SANDEN and PF condenser are working but not as cold as I'd like, I'm pretty sure it's time to dig out my old gauge set and test and adjust, know what pressures work for some one else would be handy as a starting point...

I'm running R134a now .

TIA,

-Nate

Quote:

Originally Posted by Roncallo

Big success on the AC. These taken 81° F ambient 65% RH, using standard test conditions, engine at 2000RPM windows down, blower high, recirc off. Also checked evaporator temp operation. Engine at idle, blower low, windows closed recirc on. Clutch cycled off at 32°F back on at 36° F.

What a difference with new thermometers. 40° Duct temp.

AC is done.

See Finishing Samson for pic.

Finishing Samson the M120 R107

URO Parts Support · #42 07-13-2021, 08:10 PM

Hi guys, we just completed the first production run of our redesigned Heater Valve Repair Kit 000 835 0644R, which has a softer rubber diaphragm for easier movement and some minor improvements to the smaller pieces.

These are now available in our warehouse, and should show "in-stock" on retailer websites. If you need one, don't wait too long, our next run won't be for a few more months.