Rincewind

it hit 90 degrees today and i turned on the a/c for the first time since last fall and to my surprise, i was not getting cold air!
i adjusted the temperature to 60 and still no change... the air felt like it was air from outside... i checked to make sure the button for venting outside air inside wasnt on, and it wasnt...

any ideas on whats wrong?
needs more freon?

pointman

my guess would be you need more freon.

cil254

No freon on this car.
see this post: https://mbworld.org/forums/showthrea...threadid=66901

timecop369

A/C condeser leak? I think that's what is wrong w/ my A/C.

sph17

at your A/C compressor. It usually is on the drivers side. See if the clutch is engauged and the front part of the compressor is turning. If it isn't then you may have a fuse to the compressor clutch bad, a bad connection to the compressor clutch, or other compressor clutch related problem.

vas2vas

most likely the expansion valve on the evaporator has gotten stuck.... keep engaging and disangaging auto for next couple of days to see if you can shake it loose...

Rincewind

well its not leaking...

i always park my car in a garage and i dont see any leaks on the ground...

i did however notice that when i had my a/c running (not cold) that the sound was a little louder than usual... its hard to describe... over the winter i ran with EC on alot....actually all the time

Rincewind

ok i went into my car again to turn the a/c on and off... still blows warm air....

i pushed and held the rest button down and the temperature reading was showing 88 degrees

and when i let go it went back to 65 degrees (which i manually set)

also i noticed that the "auto" red light always stays on

--------update--------------

"In some cars, people thought they were "saving" their compressors by running the system in EC mode wherever they didn't require cooling. This resulted in the demise of their compressor, as it is designed to be run continously. The compressor is lubricated by the R134A (actually, oil in the coolant) and running it is the proper state for long life."

Over winter i ran heat with "EC" on alot...

"Run through the real-time diagnosis (press the rest button for five seconds while the car is running) and check the real time data from the sensors. Then, engage the code storage and find the stored data. Someone else will have to help with that one, I can't for the life of me remember the sequence."

i had the a/c on blowing warm air... and i pressed and held the rest button... the reading it gave me was 88 degrees.... my climate control setting was 65 degrees... my garage was around 75 degrees

blackmercedes

After pressing the REST button for sive seconds, scroll using the fan button (to the "higher" side) and write down the readings for sensors 5,6 and 7. 7 should be a funny looking thing, that's okay, it's pressure in bars.

You need to find the evap temp sensor real-time reading (sensor 5) and the high-side pressure.

Is the EC button lit all the time? Check under the hood and see if the compressor is spinning.

I am willing to bet it's an evap temp sensor. <$100. Common W202 and W210 AC problem and solves 99% of those chassis problems.

STOP using the EC mode. It's not good for your AC system. The coolant (R134A) should be allowed to circulate. Mercedes went though a ton to devise the system, and it's ingenious. Building HVAC systems are working on variable pressure systems just like them in order to extend life and improve reliability. MB is ahead of their time on this one. BTW, that improvement was made in 1996 or so...

Rincewind

i took it to my mechanic

he put in 1.5 lbs of freon and now it blows cold

blackmercedes

Youch! That's TONS! You have a leak. These are SEALED systems and don't bleed coolant over time like old-fshioned systems.

Certain money that you'll be out of coolant again sometime soon. You'll have to have dye added to the system and find the leak, fix the leak and then fill the system. Curious. Leaking is rare in the 1996- W202 system. Condensor? Hhhmm...

Rincewind

i bought the car 3 years ago and never performed any a/c maintence on it...

when i bought it, it was 50k used...

i havent had a problem with it since recently when it got warm and after a long cold winter...

why do u say its leaking?

maybe the last owner had done no a/c maintence on it, so it was due for some more freon

its at 70k miles

blackmercedes

If it's not leaking, where did the coolant go? Modern MB AC systems do not require "topping off" on a periodic basis. Systems used to need this as they leaked from joints and fittings.

AC systems today are not allowed to do that. Even with R134A, you're not allowed to vent coolant into the atmosphere. Car systems must be sealed and not allow venting of the coolant. Any MB that has to have coolant added is leaking. The fact that your system allowed it out means it is leaking. I don't mean to sound like I'm chiding, but the definition of leak is not holding it in.

I just don't have any "common leaking spots" for the variable pressure system. In previous systems (1994-1995, some 96's) the condensor was often the culprit for coolant leaks. Haven't heard of too many evaporator leaks in W202 or W210 cars.

Your tech should be a little more proactive about diagnosing the problem. Let's hope it's a one time event, but if the system loses it's coolant again, don't top it off. Find and fix the leak.

Rincewind

ok will do

u dont think it needed some topping off even after 7 years and 70k miles worth of driving and use?

blackmercedes

Nope. We have a 1990 190E 2.6 at home that has not been topped off in 15 years and nearly 400K. My own 98 C230 is as old as yours and has more miles, and can turn the inside of the car into a meat locker, and the AC system has never been touched. The 190E has it's compressor cycled lots in the winter as it's used for defrosting. With the C230, it's possible to extend the life of your evaporator by replacing the cabin dust filter frequently.

AC systems in my parts last a long time thanks to low humidity (the removal of the moisture is a big job for the AC system).

If I were you, I'd drive it an see if somehow the coolant leaked in some "one time event" and hope for the best. You're not out much at this point dollarwise. If problems return, then don't allow someone to top it off again, but find the problem.

GDawgC220

how long does the freon last or whatever type coolant it uses? Just curious 'cuz my '94 C220 has never had it's A/C system touch, recharged, etc before in it's life

vas2vas

it should last for a lot of years untill a leak develops or you need to change one of the a/c components and thus empty and refill.... I don't know how long it takes for the R134a gas to loose it's cooling properties, but my 82 diesel was ice cold with what appeared to have been the initial fill of freon R12 gas....
mind you R134a is more prone to leaking since it has smaller molecules than R12 (aka freon)....
the a/c in my c280 leaked twice, first the condencer went, fixed that, then the receiver dryer went fixed that too, now I'm set for the summer.....

CBus

O.k. I am having the same problem. No compressor engaging. I am hoping some of you can help me since you have been through this.

I have a 2000 C280. The EC light is NOT on when in auto mode, and I get hot air when the climate control is set to LOW. The compressor is not engaging at all.

AC diagnostics:

01 Interior temp 69
02 ambiant temp 55 (yesterday was 88 degrees. Yeah Cleveland)
05 Evap Temp 65
06 Eng Coolant? 149
07 Refrigerant Pressure 006 (yesterday it was 009)
08 refrigerant temp 77


Is there any other tests I can do? Just recently had the blower motor replaced. Is the regrigerant pressure too low?

blackmercedes

Yes.

You'll need to have the system checked for fill level and component integrity.

DougandhisC280

I just refilled my AC for the first time since new because I had the same problem you did. It only costs $4 per can and one can made it ice cold. The AC system is under high pressure so stuff is bound to leak after a while. The can comes with leak stopping stuff in it so hopefully that will help.

Rincewind

u filled it up urself? was it hard?

DougandhisC280

It was a piece of cake. I got a can with the built on hose from walmart. It took about 5 minutes.

Rincewind

how many pounds of freon was in that 1 can?

and where do u put it lol

DougandhisC280

1 can = 1 pound. It was completely empty. I only used one can and now it's blowing at 28 degrees farenheit. 2 more cans wouldn't make it any colder because it would just sit in a tank. If I've got a leak now I'll figure it out sooner.

pointman

what the hell!?! i said freon and cil...something said i was wrong. huh!?! i guess thats what i get for believing a noob.