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  #1  
Old 04-29-2002, 10:15 PM
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Question AC compressor cutoff relay = KLIMA?

Does anyone know if the dreaded "KLIMA" valve I've heard so much about was installed into 123 bodied cars?

Is it the same part as the A/C cutoff relay? It's awfully expensive to replace, in either case.

Here's a little background as to why I'm asking:

I've recently installed a new ac compressor on my 1984 300 CD, complete with new reciever dryer, expansion valve, etc. The old compressor stopped turning on and off about a month after the coolant ($R12) leaked out. I thought nothing of this, since I planned to replace the tired, old, grime-coated compressor anyway.

I have yet to charge the system, and plan on using R406 coolant, also known as Autofrost (a lot of people in this site seem to think it's better than 134 - I'll try almost anything once).

After I oiled and installed the compressor and all other parts, I connected the wire leads, started the car and attempted to turn on the AC, briefly, to circulate the oil before filling the system with coolant.

Nothing happened. The compressor will not engage, and I think a relay is suspect. I'm hoping I'm wrong, as the cheapest places stock this thing at around $130 bucks. The fuse is good, unless there's another one some other place I need to check.

Where, exactly, is the ac cutoff (Klima-?) valve located, anyway?
I found two relays under a plastic cover on the inside driver's side fender well, but the part numbers only identify these things as each as "relay", and do not cost anywhere near what an AC cutoff relay does.


Any suggestions?

-Gil

(Why don't I ever get flat tires for problems anymore......?)

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Old 04-29-2002, 10:53 PM
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Gil - Your car does not have the Klima relay. The reason the compressor won't activate is because the system is not charged. One of the two switches on the receiver/dryer detects low pressure inside the system - anything below ~2 atmospheres - and shuts down the compressor. Trust me, you want it to work this way. Charge the system and it should fire right up.

You are going to vacuum the system first, right?!?!?
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Old 04-29-2002, 11:08 PM
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Vaccum? well.....

Uh... umm.... well, I was kinda gonna blow off this step since I replaced most of the major parts, but I'm guessing this is not a step I should skip-?

Is there really that mich crap built up in there, and will a blow- whoops! I mean vaccum- job really take care of it all? ( Sorry, couldn't resist).

What's this cost to do, as I know I haven't go the resources to do this myself.

Also, anybody know how much R12 oil (Not ester, or R134-intended oil) goes inside one of these compressors?

I've also read (anecdotal accounts) that I'm supposed to add oil to the reciever-dryer, but I can find no information as to how much. Anybody know?

Thanks again,

Gil
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Old 04-29-2002, 11:19 PM
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pulling a vacuum

The reason why you pull a vacuum is to evacuate the air and water vapor in the system before putting in refrigerant. Remember, the chemical that does the cooling is the refrigerant due to its physical properties....air and water vapor do not make good refrigerants.

Oil is usually added to the compressor, but it doesnt really matter much since the oil circulates through the entire system anyway.
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Old 04-29-2002, 11:34 PM
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Mark, I'd always heard that water moisture mixed with the R12 creates an acid which can destroy or corrode A/C components and washers/o-rings; hence the reason for having a dryer in the system and evacuating the system in certain circumstances like this one.
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1985 300SD - 'Grace' (198K mi.)
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Last edited by ck42; 05-06-2002 at 11:29 AM.
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Old 04-30-2002, 12:04 AM
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R406 is a Zeotrope blend but should work. However it will not work at all unless you pull a vacuum for at least 15 to 20 minutes before you charge the system. The problem with that blend is that you have to label the change and change out the fittings. Most of the local shops only do R134 conversions and are probably not set up for the R406 conversions. Do you know a local guy who is a HVAC guy?? He may be able to help you with the Vacuum pump out.
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Old 04-30-2002, 12:12 AM
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billrok:

The kit I got comes with the label, adapter fittings and a charging tube (which looks suspiciously like a USED R12 tube, but what the hell...)

I intend to go to a local shop and have a vaccum pulled on it, then drive it home and charge it up myself, or I could just do it right then and there, immediately afterwards.

You're right, not too many people are set up for R406, but it's supposed to be pretty good. I wish it were more popular. R134 doesn't work well in cars not designed for it, and I'm not willing to donate my first born child for a pound of R12.

Has anyone else had experience with Autofrost R406?

Gil
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Old 04-30-2002, 10:17 AM
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Yeah, you really need to pull a deep vacuum. You have to lower the pressure inside the system to the point where any water boils off at ambient temperature.

There are several reasons for this step. First, air and water are not refrigerants. Air will not condense, so does not assist in cooling. It does stress the compressor, consume more energy, etc., but for no value. Second, the water reacts with refrigerants to form acids which over time eat away at the system. This is called an acid eat out. Third, excess water can freeze inside the system and block the flow of refrigerant. This results in cyclic operation of the system - very cold, then very warm, then very cold when the ice melts....

I don't think you can have it vacuumed and then drive home to fill it - the vacuum will be lost when the hoses are disconnected from the system. You may be able to rent a vacuum pump and guages from a rent-all type of place. I've since acquired my own equipment, but that's what I used to do.
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Old 04-30-2002, 11:40 AM
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I converted to R134 and Im happy with it.

I made a few modifications to the system, while replacing EVERY component (all hoses and equipment) except the evaporator:

- I installed a generic parallel flow condenser, giving greater refrigerant cooling capacity...I had to modify brackets and had hoses custom made to fit;

- I installed a relay between compressor and aux. fan so that the fan goes on whenever the compressor does. By doing this, i'm not depending on refrigerant temp. to kick on the aux fan. (I realize I dont need aux fan to kick on at highway speeds, but I made the trade off decision to ensure adequate aux. fan operation at lower vehicle speeds, stop and go traffic, and at idle)

- I installed a dual hi-lo pressure cutoff switch in place of the original low pressure cuttoff switch, and eliminated the temp cutoff switch intended for R12, since the temp/pressure profile of R134 is different from R12

I completely flushed (forward and backward) the evaporator with solvents (laquer thinner, methyl alcohol, etc.) using a drilled-out expansion valve and original hoses as a service connection (poured in solvent and blew out with compressed air). Dried with air pump over night.

I used high viscosity PAG oil as lubricant, lubricated proper o-rings with mineral oil.

The system works very well....center vent temps down to 39 degrees F with outside temps in the nineties, with moderate humidity. During hot humid weather (temps in 90-100 range with 100 % humidity), center vent temps are in the 45 to 50 deg F range. This is simply a consequence of having a small evaporator....refrigerant temps still get down to the 35deg. range, but the evaporator is simply not big enough on these cars to blow ice cold air during very hot humid weather....works great during hot dry weather.

Good luck
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Old 05-01-2002, 01:33 AM
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Smile R406 it is

Just got done converting over to R406. SO far, so good. Had the vaccum job done for the reccomended minimum of 15 minutes and then added just two cans of Autofrost R406 and 8oz of mineral oil. Will let you know how ling this experiment lasts.

-Gil
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Old 05-03-2002, 05:10 PM
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Moraine,

when i disconnected hoses, I recall that I used standard adjustable wrenches. I didnt spray any penetrant on the fittings.

You indicated that you will be using mineral spirits to flush. Just a couple notes of caution:

regarding safety, you may be flushing with highly flammable liquid (as I did)...just use adequate precautions related to grounding and bonding metal containers to avoid static sparks, and watch out for ignition sources, and do the work outside....

From a performance standpoint, the more flammable liquid is preferable since it is more volatile...therefore, solvents such as pure alcohol, white gas (coleman fuel) and laquer thinner work the best, because they are not only good solvents, they are very volatile and will thus dry out better. Realize that these materials are highly flammable, and can result in an explosive vapor cloud. If you use mineral spirits, most of which are labelled "combustible liquid", while safer from a fire safety standpoint, they are less volatile, and you run the risk of leaving residues in the system. A more volatile mineral spirit (labelled as "flammable") will work better, although more hazardous.

When I did my system, I used the most volatile liquids I could find (also the most flammable/most dangerous) and used appropriate safety precautions.

I really dont know how much air you need to blow through the system to remove all solvent residues....I have access to some air pumps that do not pump much air (only 10 liters per minute), but they conveniently plug in to wall outlet, and I just let it run all night moving air through the system, ensuring that all solvent used to flush was dried out of the system......Remember that using compressed air is very good, especially when pushing flush liquid through the system...but when you blow out the system after flushing, the high pressure air does not ensure all solvent is removed. You may have "eddys" in the system, due to physical configuration, especially in the evaporator, that will not be influenced by high velocity air....you will still have wet areas in the system. By moving fresh air through the system for several hours, you ensure that any liquid left in the system will have a chance to evaporate passivley and be removed from the system. That is why I used very volatile solvents. (I didnt consider any of the commercially available flushing agents available on the market, so I dont know much about them.)

Good Luck,

Mark
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  #12  
Old 05-06-2002, 10:44 AM
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Of course, I cannot find the reference right now, but I happened across the web page of an a/c shop owner one time. Among other topics, he discussed flushing systems. His shop generally used mineral spirits, though he said lacquer thinner was a fine choice as well. The main difference being mineral spirits are ~$3/gallon, while lacquer thinner is twice that, but more volatile.

My opinion is that it's not necessary to blow air through the system to dry it out. Remember, when it is pumped down, any remaining solvent is going to boil out in very short order. Any half decent vacuum pump will pull the system down to the point where water boils at -5F, let alone volatile solvents like lacquer thinner or mineral spirits.

When cleaning up my 124 after a seized compressor I flushed the system and blew out the components just until the exiting air no longer felt wet with solvent. Reassembled, pumped down for about an hour, and all has been well ever since.
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Old 05-06-2002, 03:31 PM
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I used lacquer thinner, but I was only doing one. If you were in business for yourself, you'd be concerned about the cost of the flush - and everything else!

Adding oil is easy - wherever is convenient! Seriously, so long as there is some oil in the compressor, you can add fresh oil anywhere else in the system - it will migrate through the system when it's charged & running.

On my 124 car the most convenient location was where the suction side of the manifold hose assembly connects to the hard tubing from the expansion valve. It's up high on the drivers' side wheel well. Just unscrew the coupling using two big wrenches. I stole one of my wife's measuring cups from the kitchen (Shhhh...don't tell her) and just poured the refrigerant oil down the manifold hose toward the compressor.

If you're working on a 123, doesn't the suction side run parallel to and just behind the top of the radiator? It should be real easy to disconnect this and add some oil. Now, if it's been a while since that particular junction was apart, you should replace the o-ring. Be sure to lubricate the o-ring with refrigerant oil before installing - they don't work too well when they get pinched.

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