my saturday fun of "downgrading" a 300SD to R12 - PeachParts Mercedes-Benz Forum

vstech · #1 06-26-2010, 09:48 PM

first off, if you have 134 fittings on the condenser line, LEAVE them! I put a wrench on the line to remove the fitting, and POW!!!! the entire 134 charge went out in one fell swoop! the fitting popped right out of the line.
i used almost no force, it just picked that time to release. my guess is the guy who put it on really tightened it.
anyway thayer the member whose car I was working on took it in stride, as I have plenty of parts cars to pull lines off of... until the flange would not seal on his ebay compressor... the steel plates with imbedded orings would not reseal, so off to the parts house... nope. off to another parts house... new compressor... got it changed, sealed up great. flushed and evacuated weighed in the charge of 12, cranked up the car... no clutch engagement...
we go back to the store... no more compressors in stock... we break for a meal.
and kent has an epiphany... lets hit it...
it works. the clutch engages with a tap from a wrench, so I start wondering how to hit it with the motor runnign... kinda dangerous with a wrench... i go get a branch about 2' long... it works...
so I made him a nice "clutch engagement tool..." a bent branch!
he is soooo happy. the system is putting out 30degree air. and cold at idle in the cabin of his BLACK sedan!
we do some more evaluating, adjusting of his pedal linkage... very difficult to press the accelerator. found it to be binding on the ramp on the linkage on the valve cover, adjusted the cruise control to keep the ramp past the hump. yaaaay! smoothe pedal.
still. thinking on the a/c I get the idea to rev the motor. and the clutch engages on its own...
hmmm...
trusty multimeter out and it's sitting just barely on 12v... at idle... hmmmm turn off the ac... voltage creeps up to 13v... hmmm.
turn on the ac it clicks right in. hmmm.... voltage drops a little around 12.89 or so... battery looks good, he says it's a year old. glow plugs were energized and the voltage drops below 11... then start, then the clutch needs power, voltage is dropping low. rev the motor and the alt raises the voltage enough to pull in the clutch. success.
I'll check it more on monday,
I'll leave it up to thayer to post his pic with the a/c engagement tool...

so all said and done, a 1 hour reclaim and recharge with r12 took...

9 hours in the HOT HOT sun...
yeah me...
really fun, but wow a lot of work...

leathermang · #2 06-26-2010, 09:52 PM

At first I thought Thayer was lucky to have you working on it...
then .... the big stick...???? I am wondering now....
and it is one thing to do something... and another to ADMIT TO IT....
LOL

vstech · #3 06-26-2010, 10:00 PM

hey, hitting it was his idea...
I just did not want him to get his hands near a spinning power steering pulley...

vstech · #4 06-26-2010, 10:02 PM

yeah, since we were pulling the compressor, we went ahead and flushed the condenser out. man there was a lot of trash from the original failed compressor in there... squeaky clean now!
he's got a new compressor, and a super clean flushed out condenser, and a new dryer, and super cold working a/c!
what could be better?

leathermang · #5 06-26-2010, 10:15 PM

What is that metal thing which attaches to the actual compressor ?
Can not think of the name..
but the FSM says in the case of a compressor blowup that needs to be NEW..
since they say it can not be cleaned.... which I assume they mean there is a permanent filter in there which can not be replaced or cleaned properly...

techguy512 · #6 06-26-2010, 10:25 PM

Quote:

Originally Posted by leathermang

What is that metal thing which attaches to the

I think that's the manifold line....

dantheman67 · #7 06-26-2010, 11:12 PM

Nice. 30 at the vents.. Sounds like a good downgrade.

Hitting the clutch with a stick to get it to engage?? :O

vstech · #8 06-27-2010, 12:05 AM

Quote:

Originally Posted by leathermang

What is that metal thing which attaches to the actual compressor ?
Can not think of the name..
but the FSM says in the case of a compressor blowup that needs to be NEW..
since they say it can not be cleaned.... which I assume they mean there is a permanent filter in there which can not be replaced or cleaned properly...

all I can think of that's connected to the compressor is the flex lines themselves. there was no filter in there. perhaps they meant the rubber cannot be cleaned when residue from a blowup is done. so in that case, it's a good thing I replaced all that with the new compressor I installed today!

thayer · #9 06-27-2010, 02:32 PM

it is fascinating reading about yesterday. there was so much that went wrong...but hey..if your ac is gonna break...john's house is the place to have it happen. Im anxious to see just how cold i can get it. we read 18 degrees on the blue line in the engine bay. Only the highway will tell. its going to be a hot one back to mayberry today so that will be the real test.

i would also like to confirm that his 300sd will reach 60 in 8 seconds. i was in the car when it happened.

thayer · #10 06-27-2010, 02:36 PM

Quote:

Originally Posted by dantheman67

Nice. 30 at the vents.. Sounds like a good downgrade.

Hitting the clutch with a stick to get it to engage?? :O

you cannot begin to imagine my joy when the clutch engaged. totally worth hitting it with a stick. of course now i just accelerate and it engages....right at 13 volts.

And my exact phrasing was .."why don't we just give it a little tap"

leathermang · #11 06-27-2010, 05:47 PM

Thanks,
The MB AC FSM says that in case of blowup of previous compressor that manifold is supposed to be replaced. That it can not be cleaned and thus jeopardizes the new compressor.

vstech · #12 06-27-2010, 09:51 PM

two things need to be added to this thread.
one, the compressor I installed was mounted and bolted in by kent, I made him be the one under the car... and used his face to catch the oil and wrenches I dropped under there... (sorry kent) also, on the 8 second to 60 run, it was downhill, so it hardly counts as a verification of the acceleration prowess of my car. but on an uphill run, fairly steep uphill run with my two girls in the back seat, and he and I up front, it took 10.9 seconds to 57mph... pretty fast. I love my 82SD!!!

leathermang · #13 06-27-2010, 11:00 PM

One more thing needs to be added..
when you are the one on the bottom... with people dropping wrenches on you.. do not smile... it can save a tooth....

thayer · #14 06-28-2010, 07:04 AM

Quote:

Originally Posted by leathermang

One more thing needs to be added..
when you are the one on the bottom... with people dropping wrenches on you.. do not smile... it can save a tooth....

Luckily I caught the enormous washer with my eye, and his wrench with my forehead.

vstech · #15 06-28-2010, 09:41 AM

Yeah, his teeth were fine.