AC blows warm on driver and cool on passanger!
 

On my '99 E320, the climate cotrol blows so-so cool on the passenger side, but blows warm on the driver side, when set to LO or 14degree temperature. Which part am I looking at replacing? Thanks a Lot!

Do a search - sounds like your charge may be low...

Your low on refrigerant. You'll need to recharge it and look for leaks.

Warm and cold on different passengers?
 

You have a really modern Mercedes, with selective heat by position in the car!! Perhaps you can sell that system to others?? (Just kidding) BC

Wouldn't that be "zoned climate control?"

Check your heater hot water control valve (duo-valve);solenoid valve which controls the flow to each side of the heating; when faulty it defaults to full flow, probably one side of yours is faulty therefore constant hot flow , to check disconnect power lead at duovalve then both sides should run hot no matter where temp.controls are set.
See here, http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1SL15BCKH1SL15C9I7&year=1998&make=MB&model=E-320-005&category=R&part=ACC+Mono+Valve.
Geo

Thanks Shandy
 

Thanks Shandy for the first input that makes sense. I knew I didn't have a leak or was not low on charge, as my compressor turns and stays on all the time. Other ac guys also suggested the heater valve, i was just looking for re-assurance. I allways ask for multiple opinions. If there is anything else you can think of, please let me know. Thanks again.

Hot & Cold
 

My parents S class did this about two years ago, changed the likely culprit the water valve as mentioned by Shandy. In our case it did not fix it.

The problem was Mom on the passenger side was aiming the cold air away from her and the cold air was blowing onto the temp sensor triggering it to blow warm on her side only.

It probably is the water control valve like Shandy says but check the vent aim first.

What part of our advice regarding charging doesn't make sense? I have personally experienced the issue you described, and it was in fact "cured" by a $7 can of refrigerant from Wal-Mart. Due to the variable displacement design of the A/C system in the 210, the evap can put out a warmer temp to the driver vent if the charge is low. Usually if middle is cool and both outer are warm, it's the duovalve. If warm on driver's side and progressively cooler towards passenger side, it's low refrigerant charge. This is a very, very common problem. Of course it is also entirely possible that the duovalve is bad - if you want to throw more money at the problem be my guest.

I told you to do a search, did you? Well I did - look HERE. This is just one thread - if I had the time to search properly I could come up with 20 or 30 threads that detail this exact problem being caused by a low charge.

You got multiple opinions but only accepted the one you wanted to hear. Why be so quick to discount advice that you asked for? With only 3 posts it's obvious you're new to this forum and I suggest SEARCHING and, above all else, if you're going to ask for advice then it might not hurt to listen to others who have been there done that. Oh, by the way, whatever the fix ends up being, please report back so you can help others in the future who do a search on this topic.

Thanks for the link gmercoleza
 

Thanks for the link gmeroleza, however, the thread you linked me to explains that low charge was NOT the problem.

You are correct, low charge was NOT the problem. But then the problem wasn't exactly like yours, was it? READ IT AGAIN:

Notice, his symptoms were hot/warm air on the outboard vents, nice cold air on the center vent. This is not the same problem you are having. Per your description:

Your symptoms are entirely different. Warm on driver's side, and progressively cooler towards passenger side. You never said anything about cold air on the center vent. Are there some details you haven't told us?

I consider stevebfl to be one of the resident A/C experts. Notice what he says, which backs up what I said:

Notice, he says "I have had the dual heater valve cause the outsdie ducts to be warm." Again, I will repeat: Usually if middle is cool and both outer are warm, it's the duovalve. If warm on driver's side and progressively cooler towards passenger side, it's low refrigerant charge.

It's obvious I'm not gonna convince you. Go ahead and order the valve for $166 + shipping, and let us know if it works.

Dear gmercoleza, obviously I'm gonna check the charge first. If my charge is sufficient, I'll change the duovalve. If my charge is low and after re-charging my probles go away, I will not replace the duovalve obviously. Thanks for your thorough inputs. I will keep you gentlemen posted.

95% of the time when i see this same issue it is low freon, definately start there first.

What now?
 

Dear friends,

I've gauged my AC charge this morning, the reading was over 50psi= full.

Guess I should move on to changing the duovalve?

Connecting a charge hose isn't the answer...have the system discharged & PROPERLY recharged with the correct weight of refrigerant!

50PSI means little OR nothing! a normal system at rest at a temp of 70-80F will read at least 100psi. but again it isn't all about pressure but about correct refrig charge by weight!

YOU description sounds like a LOW charge of R134a not a bad valve!

i agree, recharge the system!!

Was the engine running when you took the measurement? What was the ambient temperature? And was the A/C engaged with temperature settings to max cold? What are you using as a gauge? Please tell us you're not using one of those recharge cans with the built-in gauge. That only tells you low side pressure, which is only half the picture - you really need to know high side pressure. Check both high and low pressures with a manifold gauge and report back here with the readings as well as ambient temperature so the experts can chime in.

Charging by weight is preferable, but it is also possible to charge by pressure using the manifold gauge.

Again, it really seems like your charge is just low. Hang in there...

Thanks MBDoc !!
 

Thanks MBDoc for your input. How do I discharge the system on my own properly? Also, what is the correct weight of 134a I have to use in a '99 E320? Also, can i use ENVIRO-SAFE ES-12a instead? If so, how much weight of Enviro should i charge into the system?

Do a search on alternative refrigerants - the bottom line is that they are actually blends of other refrigerants, and each individual component leaks out at different rates which changes the overall blend. So when you're low you will have to discharge and recharge all over again.

What's wrong with R134a? It's really cheap, about $7 a can. Your system probably takes 2 to 2.5 12-oz. cans. Maybe the experts can chime in here as to the exact weight, again I usually charge with the gauges and not by weight.

Approved equipment should be used to properly discharge the system; it is illegal to just "vent" it to the atmosphere. So unless you have the correct equipment, your best bet is taking it to an A/C pro.

HOW to discharge?
 

Dear gmercoleza, the question is: HOW TO discharge (given that one is using proper equipment)?

Follow the instructions that came with the evacuator.

Yes, just hook it up and turn it on.

Evacuator
 

Guys, you're all very kind, but I'm less mechanically inclined than you think:

-What evacuator?..where to get one? (Can't i just use my air compressor?)
-Which side do I hook it up to? Low pressure or high pressure?
-Does it hoop up the same way (same spot) as the refrigerant can will later?
-Is the evacuator a pump, or a blower?
-When I flush, where do I pump air in, and where will everything escape out?
-Do I need to flush, or evacuation IS flushing?..
-also, by charging enough weight of refrigerant, will it guarrantee full pressure,
or pressure and refrig. amount is two different things and are done separately?

Thanks for your patience.

Hey OnlyBenz,
These guys have been trying to be nice to you, but your last answer makes it very clear to everyone that you don't have the slightest idea of how to service an AC system, and don't have the specialized tools that are ABSOLUTELY necessary to service the AC system. Take it to an AC specialist, or you will end up costing yourself several thousands of dollars.

Regards,

Wow
 

Richard,
Why the arrogance? I do acknowledge that the guys are nice to me, and I don't show them any disrespect. I will be servicing the AC system on my own, that is why I'm here, to gather information. It will not cost me thousands, as it will not go to an AC profesional. If taking it to an AC pro was my intention, I wouldn't be on this forum.

An evacuator is a special pump. Expect to pay $400 or so for one, plus the recovery tank that you'll need. Besides removing the refridgerant from the system before doing work, it also removes the air when you're ready to recharge.

The evacuator does not flush the system. That's a separate job, which requires dismantling the connectors and flushing fluid through the lines, evaporator and condensor. You don't flush the compressor, but just remove it from the car and drain any oil.

It would seem that you would be better off with just a set of gauges. This can be had for about $100 or so, and you'll need it in addition to an evacuator anyway. If you haven't done so already, get the climate-control troubleshooting manual for your car. It has the pressure charts for the system.

Hi Only Benz,
I wasn't trying to be arrogant! I was giving you my best recommendation based on the questions you asked in the previous post. In order to evacuate, flush, and recharge the AC system you will have to buy:

1. Manifold gauge set

2. Refrigerant recycle/reclaim unit, around $500 used on Ebay, or over 2K new.

3. Refrigerant tank to go with recycle/reclaim unit, they are a special tank with three valves, at least that's what my Robinaire unit takes.

4. Flushing solvent

5. New O-rings for system (recommended for all fittings, required for connections that have been disturbed.)

6. New receiver/dryer, required when system has been opened.

7. Fresh lube charge

8. Fresh refrigerant

9. Some way of measuring new charge, measuring by weight preferred but requires special equipment.

If you want to play with your AC system, that's certainly up to you, but if you fail to observe the necessary steps you will contaminate the atmosphere, your car's AC system, and most likely take out the compressor in short order. If you "want to do it yourself", you will have to spend more money on the REQUIRED equipment to do the job than it will cost to take it to an honest independent AC shop.

My recommendation comes from over 45 years experience in the business.
Once again, I'm NOT trying to be arrogant, just trying to advise you the best way I can.

Good luck with it.

Thanks Richard
 

I think I've come to a decision on how to proceed. Here is what I'm gonna do.
I've checked my compressor, it turns on and never shuts of, and it's dry, free of oil stains etc. My blower is good, as the force of incoming air is not weak.
My condenser should be good, as i get cold air on the passanger side. My control panel should be good, as air is coming from the proper outlets as switched around etc. I found some oil stains on some of the rubber hosing. So:

I have bought these brand new Benz parts (cheap on ebay!) just in case:
-hosing and o-rings for both low and high pressure side
-heater douvalve
-receiver/drier
-expansion valve
-cabin air filter

I will take the car to an AC Pro, have him replace the above parts (and pay labor only), then have him evacuate and re-charge.

My qestion is: Is it legal (in Canada) to perform evacuation and re-charge WITHOUT a leak-check?

I've been waiting to see how this story will end. Only_benz, I admire your determination, but you're throwing money at the problem when your intention is to save money. The wise thing to do would be to have the system topped off and add some dye. Drive the car for a few days and re-check for the leak. The money you spend paying a professional to do this will be less than you'll spend replacing parts that aren't bad. The members on this Forum have given you EXCELLENT advice. You'd be crazy not to take it. :wacko:

Indeed, you need to check the pressures before you even consider evacuating the system, and add some refridgerant (and perhaps dye) if it's low.

You're trying to kill an ant with a sledgehammer here. You could be just a bit low without having a leak big enough to worry about.

As to whether you can evacuate and recharge without a checking for leaks, that's pretty much physically impossible. Evacuating itself will do the leak-check for you. If it won't hold a vacuum, there's a leak and there is air in the system due to that leak. You do not want to mix air and HFC134a in the system, as the refridgerant is known to be combustible when in the presence of air at high pressure.

As I said before, get the climate-control diagnostic manual (I paid about $50 for my copy), and a set of manifold gauges from any auto-parts shop. Don't just throw money at it. But definitely replace your air filter. I replaced mine the other day, and it was black as my heart.

But of course, it's your car. I'm just telling you what I would do if it were mine.

Note: If you do take my advice and get the manual and gauges, the low-side port is the one on the driver's side in the engine compartment, kind of between the brake master cylinder and the ABS controller. The high-side port is behind a small cover just in front of the top driver-side of the radiator. You'll have to remove the inside grill, just in front of the electric fan set, to remove this cover (no tools are required).

Charge is low
 

Same thing happened to me when i first got mine, get a vac and recharge.

One more little thing..!
 

I will take it to an AC Pro and have it evacuated then re-charged.

I forgot to mention: There is a hissing sound coming out of the AC system. Intermittent, but it's there most of the time. Does this fact change the situation
(and required repair action)?

It is unlikely that the "hiss" is a leak, since you still have some cold air. A leak that you can hear, would empty the system in minutes, if not seconds.

Most likely, the "hiss" is what real pro A/C techs ( I'm not one!) report as refrigerant hissing thru the TVX when there is a low charge situation. This hiss probably confirms that you need more refrigerant in the system so I'd continue with your plan.

Thanks everyone!
 

THANKS everyone, you've all been too kind, I will proceed with evac/re-charge and have an AC pro do it. Thanks for all the input!

And they all lived happily ever after.:D