A/C time, two quick questions... - PeachParts Mercedes-Benz Forum

Hit Man X · #1 04-25-2009, 09:40 PM

I guess this is relative since I'm trying to finish up the SD before it's real hot.

Is the red temperature switch on the dryer the most updated design? 004 820 68 10 is the PN for it, I have seen a few green around on some vehicles so I assume that's the old switch. I'd prefer something that'll drop the fans on sooner but if this is it, so be it.

Lastly, is there any preferred way to evac a system that still has refrigerant? This is on my 300SE that still has some 134A that I do not want.

leathermang · #2 04-25-2009, 11:09 PM

There may be different activating temperature switches... but they might have just changed the color without making any differences over this long a time period...might want to check with MB or Phil on that one .... but I will look in my AC manual to see what they say also... you are sure it is the temp and not the pressure switch ?
I think even with 134a you are supposed to find someone to evacuate it... will you be flushing it to do a clean changeover to the R12 oil ?

Hit Man X · #3 04-26-2009, 12:07 AM

Quote:

Originally Posted by leathermang

There may be different activating temperature switches... but they might have just changed the color without making any differences over this long a time period...might want to check with MB or Phil on that one .... but I will look in my AC manual to see what they say also... you are sure it is the temp and not the pressure switch ?
I think even with 134a you are supposed to find someone to evacuate it... will you be flushing it to do a clean changeover to the R12 oil ?

AFAIK it's the temp switch. Pressure to flip on the compressor is the smaller one. I figure if we can get a lower temp switch it'll kick on the Aux fan(s) faster for better low speed/stopped performance.

Yes, I'll be flushing it. No telling what sort of oil is in there.

leathermang · #4 04-26-2009, 12:15 AM

There are several people who have suggested wiring the aux fan to be on all the time the car is running... and since in ANY AC system the limiting factor is AIR ACROSS THE CONDENSOR this sure makes sense to me.... rather than messing with that switch...

Hit Man X · #5 04-26-2009, 03:09 AM

Hm... interesting wired up all the time. Just seems like it'd not make much sense on when cruising. Oh well.

thanks again

leathermang · #6 04-26-2009, 09:59 AM

Have you really examined , cleaned and straighten both your condenser and radiator ?
A few bugs, a few rocks, a few missed handles on ratchets... add up over the years...
Often 20 percent or more of the flow blocked.... a way easier way to improve by large amount the cooling ... since it attacks the efficiency AT THE BOTTLENECK of the system than that switch could possibly have by itself.

Matt L · #7 04-26-2009, 01:38 PM

It's somewhat difficult to get someone to recover your existing refrigerant unless you can tell them for sure that no sealers have been used. Most of us with pre-owned (several times over) cars have no idea.

If you find a shop with a refrigerant identifier, they can tell you what's in there and whether they can extract it. Expect to pay for this service, because the identifier uses a replaceable filter (which they will have to throw away if there is any sealer present), and costs well over a grand for the tool. Of course, any shop with a refrigerant identifier will very likely have the recovery equipment and if your system is clean, they will usually recover the refrigerant for a very small charge.

leathermang · #8 04-26-2009, 05:44 PM

Amen to that... Can you imagine finding somone to service a Duracool or some other off the wall replacement ?

Hit Man X · #9 04-26-2009, 06:29 PM

Quote:

Originally Posted by leathermang

Have you really examined , cleaned and straighten both your condenser and radiator ?
A few bugs, a few rocks, a few missed handles on ratchets... add up over the years...
Often 20 percent or more of the flow blocked.... a way easier way to improve by large amount the cooling ... since it attacks the efficiency AT THE BOTTLENECK of the system than that switch could possibly have by itself.

Come now...

Radiator is new in this car and I pull the AC condensers when the system has to be fully repaired. i.e. big flushing, major component replacement, etc.

leathermang · #10 04-26-2009, 06:42 PM

Remember, I am flying blind in trying to diagnose these things.... only as good as the description people give for the most part...
I do not see the fact that the radiator is new in the thread until that last post...

Hit Man X · #11 04-27-2009, 07:06 PM

Quote:

Originally Posted by leathermang

Remember, I am flying blind in trying to diagnose these things.... only as good as the description people give for the most part...
I do not see the fact that the radiator is new in the thread until that last post...

Makes sense.

brandlj · #12 04-28-2009, 10:27 AM

I have the red switch on my 86 300sdl. It is the switch that turns on the low speed electric fan. I made a jumper wire and unplugged it and jumpered the two wire together and my fan runs all of the time now. It really helps in stop and go traffic. My 86 300sdl has been converted to 134A. In the fall and winter I take my jumper wire out and hook up the switch again. In Hot, Humid, NE Louisiana, I need all the help I can get with my A/C. My interior is dark blue so that adds to the heat sink of the car.

daw_two · #13 04-28-2009, 10:45 AM

Quote:

Originally Posted by Hit Man X

Come now...

Radiator is new in this car and I pull the AC condensers when the system has to be fully repaired. i.e. big flushing, major component replacement, etc.

Hey Hit_Man_X,

Are you saying you pulled the condensors to flush them? I'm getting ready to tackle this job myself and I'm just looking for other's experience.

Thanks and keep posting your progress.

leathermang · #14 04-28-2009, 04:04 PM

I have seen pictures of other condensers being flushed laying horizontally....
I do not remember if the FSM says anything one way or the other... but I suspect that position would do a better job of flushing than upright....

Hit Man X · #15 04-28-2009, 06:55 PM

Quote:

Originally Posted by daw_two

Hey Hit_Man_X,

Are you saying you pulled the condensors to flush them? I'm getting ready to tackle this job myself and I'm just looking for other's experience.

Thanks and keep posting your progress.

Well for ease of flushing, I don't want flushing agent spraying on my paint.

And so I can clean out the fins of the condenser.