A/C recommendations for the MB vehicles - Page 20 - PeachParts Mercedes-Benz Forum

SpecialDelivery · #**286** 11-03-2012, 11:44 AM

After discussing this very topic with several lifelong members of the industry, they were 1000% in favor of the Sanden. when I told them that a forum member had made a bracket kit they basically said you'd be nuts to put an r-4 back in the car if you could put in a Sanden. I have more pressing issues with mine but the AC is getting rebuilt w a Sanden and converted properly to 134a, eventually....

my123ca · #**287** 11-03-2012, 06:37 PM

Eventually thats my plan too, but i already have an R4 which i bought 10 years ago so i would rather use it than throw it away or find a buyer for it.

SpecialDelivery · #**288** 11-03-2012, 07:57 PM

Quote:

Originally Posted by my123ca

Eventually thats my plan too, but i already have an R4 which i bought 10 years ago so i would rather use it than throw it away or find a buyer for it.

put that ****e on ebay for some purist to buy...

vstech · #**289** 11-03-2012, 08:55 PM

wow. that's a good point you guys. especially if you can get the sanden and the kit for the price of a good R4 (200) Thayer is a good member to ask about the R4 lifetime. I put his in about 3 years ago... I gotta agree, the R4 is junk in any system not designed for the refrigerant installed. R4s last decades in properly designed systems. my 87 astro van had great a/c up until the day I crushed it last year... the 92 pickup I had had a solid original compressor, running R12. my brother has an 89 astro van that was converted to 134 in 2004 and it's running strong... my 92 2500 was running fine on it's original R4... the original R4 in my 94 pickup appears intact, but I've yet to get the truck running, so take that with a grain of salt... it however is a factory 134 vehicle, so likely the condenser is designed to shed additional heat...
my point is, a PROPERLY installed R4 should last 10 years. properly installed, means total system flush, proper oil distribution and new dryer and expansion valve, with a cleaned condenser, and the condenser should be cleaned every 2 years or so of driving... NOBODY is doing that... ask ANYBODY who has had a/c work done by me how their condenser looks when I am done... they will ALL admit it's better than it looked when NEW! I CLEAN them things!!!

SpecialDelivery · #**290** 11-04-2012, 09:06 AM

when you say cleaned the condenser ever two years...you mean the outside right? also speaking of which....do we need to change the condenser over to something else to run the 134a?

vstech · #**291** 11-04-2012, 07:30 PM

Yes, the outside. with a condenser cleaning chemical, not soap, not simple green, either an acid or an alkaline cleaner specifically designed for condenser coils.
to run 134 in an older MB that was barely designed to handle R12, either a larger condenser, a parallel condenser, or an additional condenser needs to be added to the system to keep the head pressures below the stratospheric highs...

SpecialDelivery · #**292** 11-05-2012, 07:43 AM

Quote:

Originally Posted by vstech

Yes, the outside. with a condenser cleaning chemical, not soap, not simple green, either an acid or an alkaline cleaner specifically designed for condenser coils.
to run 134 in an older MB that was barely designed to handle R12, either a larger condenser, a parallel condenser, or an additional condenser needs to be added to the system to keep the head pressures below the stratospheric highs...

Thanks for the reply vstech! Out of curiosity, why the "special condenser cleaner" what does it do that purple or simple green wont? I am looking to rebuild my system and the debate of to run r12 or to run 134a was sealed with the compressor issue and how the Sandens are supposedly so much more durable than the r4's. I would like to do it once and I would like to do it properly. Do you have a recommendation on a condenser that will "bolt on" and what about the txv? I've heard about folks drilling them to make the openings larger. I'm just figuring the txv's are made for an r-12 system like the condensers too.

vstech · #**293** 11-05-2012, 09:25 AM

normal soaps, just attempt to dissolve dirt or grease.
condenser coil cleaners are formulated to break up baked road/dirt oil etc, and they chemically lift all contaminants from the surface of the aluminum fins. they actually attack the aluminum oxide surface of the coil, lifting everything off of that, and leaving a perfectly clean aluminum surface.

my123ca · #**294** 11-11-2012, 09:37 PM

Can you comment on the L&H pressures. I got 30/105. Its around 70 degF ambient. I put in 1200 grams of r12. The system was cycling on and off. 40-44F in the vents.

The only problem im having right now is the valve core is leaking alittle. I tried to tighten it but i dont want to overdo it. Should i tighten until the leak stops?

vstech · #**295** 11-11-2012, 11:02 PM

2.65 lbs R12 in an 85 123 should be overcharged... 70F ambient, doors and all windows down, blower on HIGH I don't know... I think you should be around 200/28... but it's hard to know if you have humidity there or not...
valve core leaking, must be replaced. tightening it will do nothing. only thing you can do is put a good brass cap on with an o-ring and get it tight, or a special valve core extractor that will remove and replace with pressure in the system...

my123ca · #**296** 11-12-2012, 08:37 AM

How much refrigerant should i put? I dont have the labels on my car anymore. Thats what the FSM says. I have brass caps there right now. Are MB valve cores different from off-the-shelf ones?

vstech · #**297** 11-12-2012, 08:52 AM

nope. REFRIGERANT valve cores for R12 valves are all the same. off what shelf?
I think the 85 123 takes 2.2Lbs. I'll check my sticker inventory...

vstech · #**298** 11-12-2012, 08:54 AM

nope. 2.6lbs is exactly correct for the 85. no problem.
if the pressures are low, you haven't got enough heat to raise them, or your blower is too slow, or the evaporator is dirty or the TXV is bad...

my123ca · #**299** 11-12-2012, 09:42 PM

Thanks for the reply. I had a couple of valve cores from autozoo but they look smaller. I didnt know that valve cores for R12 and R134 are different.

SuperCow · #**300** 11-30-2012, 01:47 PM

Im going to convert my airco to R134a
How much gas does it needs?

I bought a new sticker @ the dealer:

It states 0,95KG (950 grams)
I have a 190D 2.5
I believe the R12 amount was 1KG (1000 grams)

Isn't there a 80% rule? how about that?
My airco will be filled with a profession machine, does the shop even need to know the amount of R134?