I have conquered w124 Air conditioning. Now kneel.
 

New evaporator, new dashpods, condenser, o-rings, txv,compressor, filled with ester and a whopping 3 full cans of r12. (12oz).

I vacuumed and charged with nitrogen 3+ times.


My aux fan is humming, my sight glass is clear, and have a 30 degree temp drop vs. ambient at the vent at idle.

This was my third attempt. finally got it right. My advice to others: If you are not going to do it 100% correct, you are just wasting your money.

It is 95 degrees, and I cant wait to get in my car again.


Thank you all for your valuable help. I would have never been able to do it without the knowledge of this site.

Get some driving temps!
With my crappy r134a and broken pods letting in ambient air I can pull 40-50F drop while driving depending on ambient. 115F outside I can pull 65 from vents, 90F outside I can get 40F....

....so with that great refresh you've done, you should be able to get really, really cold.

Did you use the 15cc or 17cc compressor?

I changed the compressor last year, I'll double check, but I Believe 17.

It was about 95 degrees today with blazing sun, and I was able to reach 38* after driving for about 10 minutes with the blower still on full blast.

I really need to get it on the freeway and drive it for 20 minutes or so to get it to cool down proper. I'm sure at speed, and if I lower blower speed, I'll reach the fabled 34*. :cool::D:D

95 Ambient and 38 vent in ten minutes indicates a properly performing 124 a/c system.

Nice Job! Nothing better than success. That one has a lot of labor

Yep, that wasn't a repair, it was a PROJECT! Good work!

Amazing numbers!

I wish my 201 was as good at idle! Jealous.

All my equipment is still stock. Probably should be all changed over as well.

The only problem I have with the A/C in my '94 W124T is when the car is sitting still and the aux fan is not running - the outlet temperature goes WAY up. Everything is fine, as long as the car is moving or the aux fan is on. Have any suggestions?

Best Regards,
Rob

Perhaps it is undercharged? I had the same problem in my 126 420SEL. Now its nice and cool at idle and at speed, maybe a 5 degree difference.

The aux fan should turn on within a few seconds (give or take). Your problem is that the aux fan is not running all the time.

It is activated by pressure, so an inadequate charge could do it.

After driving 30 plus miles, I find myself setting the thermostat dial at about 78*. That causes the heater valve to release, allowing some heat to mix with my a/c. It is COLD.

I am also enjoying properly working cruise control. (thanks James dean)

It's been a good week for the Mercedes.

You make me really look forward to my plans to refresh. Basically, exactly what you did.
Only change I may do is put the larger condenser in from the later models, BUT I have to deal with making or getting different hoses to reach the different location that is on the larger condenser...makes me consider not bothering.

I considered doing the same after reading your dual fan thread. Cleveland is generally milder, so I figured it would be a waste of money and effort.

It is my opinion that the 300e a/c is adequate. We have had temps in the 90's with extreme humidity, and the cabin still cools nicely.

One bit of advice: don't look at your pressures when charging, charge by weight.


I charged 3 12 ounce cans In the system. That puts it slightly under the factory charge. The last can took a long time to go in, I had to get the can very hot, and had to raise the idle to about 2k for quite some time.

Thanks. I get the opposite here, very dry, but temps ~115 in summer.

It seems everyone says with r134a charge by pressure, but with r12 charge by weight.
Kind of odd :confused:

I just do as I am told ;)

Mine is still in the shop waiting to be re-assembled. I knew that if I tore it down I would be swamped with customers cars and that is exactly what happened which is a good thing:).

Where, when, and how much ester does one add?

Thanks.

so now you have your good luck charm down to a science, when business is slow - take apart your car.

Sounds like you've come up with a way to drum up business.:D

It's sort of like the rain maker I used to have. It was called a Haybine. Every time I would cut hay with it, as soon as it hit the ground the rain would come. I called it the rainmaker.

Determine the amount from the manual. Most are 6 1/2 or 8 oz. I think. If the system has been completely and thoroughly flushed everywhere, pour a few ounces in the evap, a few in the condensor, a dab in the compressor and a few ounces in the receiver.

If it has NOT been flushed, it's a guessing game. There are little disposable gadgets you can get to push onto a port and get an oil sample. You can get an idea with them if it is over or under charged with oil, but it's still a guessing game.

Hope this helps.

Honestly, I kind of winged it on the oil.

Someone can chime in the total volume, but what Larry says sounds right.

At first, I removed the compressor. From there, you remove the receiver/drier and you have that point separated the system in 2. I disconnect the large nut near the low side port, and pour acetone in it. Chase it out with compressed air.

Be Careful, because acetone eats paint.

Do the same on the condenser side as well. Just deposit the oil throughout the system, as in do not pour it all in one spot.

Then pump down, see if it holds, then start pumping nitrogen to check for leaks. I tested at 200psi. It will vary a little bit depending on ambient temp differences, so as long as it is +/- 3 psi it fine.

Yes, that does help
 

Compressor dead in my 300TE. PO converted it to r134, so I'm following the threads here to convert back. Two years ago I replaced all the pods, and evap isn't leaking per UV dye.

So new compressor, R/D & 2 switches, expansion valve, flush everything else, and add ester as directed.

Thanks.