JFawcett, thank you for the reply! I have not noticed my engine overheating. I will check the auxillary fan as you suggest and see if that could be causing this problem. I just want to get to the bottom of this. I have only had this car 1.5 years and not quite ready to give up on it.

I know you can definitely understand about the heat in Texas! Thank you again.

Wait until July & August!

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

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1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

Have the viscous fan clutch checked also. Low air flow across the condensor is a major cause of complaints of poor A/C at idle (or real slow).

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

If you paid a shop to replace the stack of parts mentioned in your opening post and you have no cold air after all that work and your $$$$, I would take it back and DEMAND that they resolve it.

That aside, there have been many posts here about 126 owners converting from the original R-12 to the newer R-134A. Not many have been pleased with the outcome.

I do not believe the refrigerant issue in itself is your problem because you say no cold air. However, if the shop you used improves upon you current situation, do not be surprised if you never feel like the system is really getting it done.

As far as I'm concerned, R-12 is the only refrigerant to use in a 126 car.

Just my 2 cents.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

one thing you could do since condensing is the big issue with 134a is to take out condensor and using mag wheel cleaner[weak acid] clean all the black paint off the tubes and fins.this will give 25-30% improvement in efficiency.

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

Not enough air flow over the condensor could not only reduce the cooling efficiency BUT can also cause the compressor to cut-off because of excessively high pressure on the high side. So either the condensor fan is not operating or it is not operating in the correct direction (i.e. the flow should be from the outside towards the inside). I am not familiar with this car but on my 260E there is a temperature sensor on the engine block which sends signals to the climate control relay, and if this is bad, it could cause the relay to cut-off the compressor. So while you are idling, check the condensor fan and also check if the compressor clutch is actually running when the air blowing is hot. Have you checked the pressures ? What are they 1. when you do get cold air and 2. when you dont ?

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Saumil S. Patel

Without A/C manifold gauges it's hard to evaluate your system, but with a little common sense you should be able to find the problem. I have experienced your exact problem when my Aux. Fuse was blown. Replaced the fuse and all has been well since.

If your A/C is cooling when driving but not in heavy traffic, then the Auxiliary Fan is probably the problem. If it were me, I would jumper the connectors at the Auxiliary Fan Temp. Switch at the Receiver Drier (this is the one with the pigtails). This way, the fans are operating when the engine is running and you can test your A/C cooling temperatures while driving in heavy traffic and also test your fans to make sure they are operating. If the Aux. Fan doesn't operate, then check the fuse and the Aux. Fan Relay.

You have received a lot of good advice from fellow members so far.

Good luck,

Dave

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

I beg to differ on my 87 420 SEL I had the same problem and I changed the expansion valve, evaporator, and dryer with new switches.

When I pulled out the evaporator its fins were packed with years of dirt and other debris. Not allowing the blower fan to draw enough airflow to produce a good cooling result at a stand still.

After installing the expansion valve, evaporator, dryer with new switches, vacuuming the system and charging it with 134a my system runs at a cool 42 degrees at the center vents.

I am not suggesting for someone to hire someone to change the evaporator since it is like open-heart surgery and a 22-hour operation and would cost thousands for someone other than yourself to do.

But if you are capable of performing such a task then do so it is well worth it!

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William
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1987 420 SEL - Like a fine wine only better with age

Thank you for your reply wscheffer. I really appreciate it. It makes sense to me. The guy who installed the new compressor for me along with the expansion valve and drier, did inform me he was going to blow the expansion valve clean. He had my car for a cpl of weeks. I am under the assumption he did that but I will have it checked.

Thank you so much for your help.

Drive down from Ohio to say Houston, Texas this July. Spend a couple of days there driving around in stop-n-go rush our traffic. After that, head west to Phoenix, Arizona and do the same.

Check back in here afterwards and let us know how you feel about R-134A in your 126.

It may work in Ohio during the summer. Few if any who live in REALLY hot climates have had anything good to say about R-134A in a 126 car.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I really appreciate your thoughts and advice. I will certainly bring this up to the shop that has been working on it. I, being female for one (not knocking my gender here) but that plus not mechanically inclined and not to mention do not know of or even have many tools or parts need to take it somewhere to have the experts look at it. You brought up something very good and I will let them know to check it all out. I need some a/c in my neck of the woods. Thank you again and hope you are staying nice and cool!