Troubleshooting Air Conditioner Not Working

You need to start the diagnostic sequence from the beginning, get a qualified A/C tech to set up a set of pressure gauges and see what pressures are in the system at this time, it's no good looking at electrics until we know what the system is doing at this time pressure wise. THis guide will help you see whats going on to fix the problem

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

That's what they did in the first place. They AC tech checked the system/pressure, it was empty. So they filled it with freeon/oil and put dye in the system. However, despite that fact, the air conditioner is not blowing cold--not even a little bit. So what's next, isn't it time to look at the electronics? The fluid is in the system.

Has it just all leaked out again? That's why I feel you need to get the pressures re checked and a black light inspection for signs of the leak detector dye you won't see the dye with out it

I have a blacklight. I looked at the hoses and low/high pressure ports, the ac compressor, etc. with a black light and I don't see any leakage (green). Furthermore, I looked at the compressor while the car was running and the compressor runs, and the wheel spins, so I assume the compressor clutch works right? Also, other fans seem to be blowing too. What do I do now?

If the comp is running the electrics will be ok, check that the blend doors are working, they may be stuck open and you are not getting the cooling you expect, is the comp cycling and is the pipe coming out of the compressor cool to touch?

I'll try to get under the vehicle and check if the pipes are cold. But the comp runs and the clutch engages when the climate control unit is turned on.

How do I check the blend doors?

may need a dealer to run a HVAC test, this will show if blend doors are working, generic scanners will not do this and i doubt that you will get a visual or hear them operate.

So I got a hold of a proper scanner, and ran the AC tests. I got these DTCs:
B15C8 Left Blending Air Flap Actuator Stiff or Blocked.
B15C8 Left and Right Footwell Flap Actuator is Stiff or Blocked.

I also had one for B1460 Blower Regulator, but after I reset the codes, that one went away.

So I have these questions:

If only the Left Blending Flap (LBF) has a problem, shouldn't I only be experiencing a problem on one side of the vehicle?

How come there is not even a TINY bit of cold coming from ANY vent? It's all hot.

I did a live data test, which confirmed the fault codes. The position of the Actuator Motor was not the same as specified by the Control Unit, during the live test on the LBF. Same thing was true for the position of the Left and Right Footwell Flap Actuator Motors (there was a huge difference between their positions and the values specified by the Control Unit).

There were some other results too. For example, according to the test, my Compressor is running at 70%. The Air Conditioning/Engine Fan runs at 40% when the AC unit is not on AUTO, but runs at 100% when AUTO is switched on.

Also, when the the Climate Control unit is on, but is on manual, then you can't really feel that much air coming through any of the vents, and the car is quieter. But when you turn on AUTO, the car gets louder, and more air is coming through the vents. But it's all hot air.

Anyways, what do you think is going on here? Again, there are mainly two things that are really bothering me:
1) The fact there's no cold air coming from any vent
2) The test seems to be suggesting a problem is ONLY at the footwell and left blender flap

Also, if my the air conditioning system is operating properly, what would be some normal values for the Coolant Temperature, Evaporator Temperature, and the Blower Motor Regulator? Also, how many PSI/bars should be in the system?

i will see if i can find a schematic of the A/C system, the stuck blend door may be the main heat feed and it is diverted internally, i will look into it.

I was able to reset the position of the blend doors using Defrost + Recirc buttons while turning the iginition to the ON position, I let it run for awhile. Then turned off and restarted the car. The blend doors reset. That procedures also moves the footwell doors.

There's definitely a problem with the footwell doors, however, the AC is blowing HOT regardless of where any of the doors are positioned.

The remaining DTC is just L&R footwell actuator motor. Otherwise, compressor 70% refrigerant pressure around 5-7 bar while the AC is running. It fluctuates a little bit, depending on which setting and the temperature outside I guess.

Last night was cold, it was around 5 bar. Today, it was around 7 bar.

Anyways, what's next? I think these doors are not the reason it is only hot air.

Do you have pressure readings from high and low side while running?
Gauge readings for common problems:

Gauge Reading:

Low side: HIGH
High side: HIGH

Potential Problem:

• Too much refrigerant.
• Poor condenser airflow.
• Non-condensable gases (air) in the system.
• Moisture in the system.

Gauge Reading:

Low side: LOW
High side: LOW

Potential Problem:

• Not enough refrigerant.
• Compressor problem.

Gauge Reading:

Low side: LOW
High side: HIGH

Potential Problem:

• Expansion valve plugged
• Orifice tube plugged
• Restriction in screen (receiver dryer)

Gauge Reading:

Low side: HIGH
High side: LOW

Potential Problem:

• Compressor valve problem.
• Missing orifice tube.

Gauge Reading:

Low side: Vacuum
High side: HIGH

Potential Problem:

• Low side restriction
• Plugged orifice tube
• Plugged expansion valve
• Moisture in the system

im still waiting on my manifold gauge to arrive. what are the specs for how much r134a and oil should have been added to the system?

did you find those details? i looked for the sticker on my vehicle, couldn't find it anywhere

comp oil is PAG46 use 4.00oz
There is no volume for refrigerant, it tells me to refer to label on car, it also should be in the specs section of your owners manual.

Yeah, I found a Benz specs sheet for my car. It uses 4 oz PAG ISO 46 like you said, and between 700-750 grams of the 134a.
I have a question for you, since you didn't cover this in your compressor video, but if you have a A/C gauge manifold with the three hoses, how do you use it to add the PAG oil?
The PAG oil I bought is not in a pressurized container, so how do I get the hose to take it?

Do you know...if my A/C system has less than 700 grams, would that cause my A/C compressor not to turn on?

Not sure what the low pressure cut out is, can't find that anywhere, but needless to say low pressure will be a cause to shut down the system, you can bridge out the low pressure switch to see if this is a factor. As for adding oil the machine i use has an automatic oil feed built in to he system, other machines have an oil injector fitted to the induction low pressure port.

Hey, when I actually got under the vehicle and looked at the compressor, I noticed that the clutch is NOT engaging. I added about 6 oz of 134a, and still no change. I still haven't got my manifold gauges, so I can't do low and high side comparison.

Anyways, what's next? What are the potential causes of clutch not engaging, and how do I rule them out? I know once I have the manifold gauges, I'll be able to compare Low Side vs. High Side using the info you provided. But for now, what should I do?

I don't think this model has a clutch style compressor, it is internal valve, check out this video it will show you about half way through

https://youtu.be/_pBoAA87gHI


Have you checked the outgoing ac tube to see if it cold?

check this article out

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

let us know what you find

There's a brown thing in front of the compressor pulley that looks like a clutch. What is it? I can take a picture and post it later. If that's the case, then the AC compressor definitely runs.
I hooked it up to manifold gauges today, and the pressures did not change while the vehicle was the air conditioning was put to ON or OFF. Also, it was clocking very high low side pressures, over 110-120psi (that's with car ON or OFF). I couldn't get an accurate high side read, because the hose was super leaky at the high side gauge. I read around 120-130psi on the high side...ambient temp was around 80F.

No the hoses coming from the compressor are not cold. No difference in temps.

As far as my diagnostic OBD II tool AAC tests, it shows that the compressor runs at 70% and it draws from 12-13.5V, depending whether on Manual or AUTO.

The only fault codes I see are:
1) R&L Footwell Flaps Actuator is stiff or blocked
2) B1630 Fault in CAN communication with control unit OCP

What should I do next?

Please use a test light and probe the single feed wire that goes to the compressor with the system on, it should light up, you will not be able to tell if the compressor is working by looking at it like the old days.

I tested the wire to compressor and it has power. Also, my OBD tool was able is able to transmit data from the compressor turns on and shuts off. It shows the unit go from 0% to 70% when it is powered on, including showing the voltages as I mentioned 12-13V.

This is what my compressor looks like. It's got a metal piece on the front, which seems to be a clutch (which is not engaging). The product info is DENSO ASSY 447220-8843. It seems to be for European c-class models.

What do you think, does this compressor have a clutch or not?

Nope, no clutch on that one buddy, Internal valve model. I think its time to check out the video because you will need to replace the compressor.

Ok, thanks for confirming that. I thought that hub-looking thing was a clutch this whole time. That helps a lot!

I'll definitely be studying the video. I'll replace the compressor and let you know the results afterwards. Hopefully this solves the problem!

How many ounces of oil come with the new Denso unit? And what kind of oil did you add to the new unit before installing.

So when you add the oil to the compressor, that means you won't add any additional oil when you recharge with 134a right? Because presumably, it should have the oil from the Denso unit + the 2 oz that you added.

The denso comes with oil, I like to give a little extra to make sure the system is well lubricated, like 1/2 once extra should do it. Let us know who it goes

Im still waiting on the part, should arrive by this weekend.
Do you know the size o-rings you needed for the hoses (the o-rings that you replaced)?

I dont know the size of the o ring , we have a universal kit and just matched them up :)

Not done anything w compressor, or touched drive belt or anything

Hey KEVINM01,

Yep just had this problem with the car I did the compressor on, the starter was bad, put I new one in and its being starting up ever since,. When it rains it pours buddy,

here is a guide to let you know what you are in for.

https://youtu.be/iySmMQM5OLE

different car but same operation

Let me know what you find

Ok, I'll order the part. That means it's gonna be a while before I get to the compressor.

Okay let me know what happens

I did a preliminary check to try and locate the starter and see how I will access it once I get that part....it doesn't look so straightforward. I got under the vehicle to see it, and I couldn't see really even how to get it out.

Just take a look at these diagrams. How do you get to it? It looks like #37 and #17.
Let me know if you instructions or ideas on how to approach this. I think accessing the starter was easier on the Ford.

Upload the images please use the link right below the text box

Oh...so these were the images I was referring to. I realize that's probably not the M271 engine, but the layout is similar. I pulled that from a website that was written in Russian, so I don't really know what it says since I don't speak/read Russian.
Problem is, you don't really see what it looks like next to the bell housing from these pictures. I'll post some pictures from my car later on this week when I get a chance.

Okay sounds good, I know the starter is tough to get to as in almost everything in this car is rough. :) But if it was easy everyone could do it, not just the talented, so consider yourself one of the few that can work on cars.

Haha, I'll keep that in mind. Well I'm definitely trying to learn to become talented. Things are definitely challening on this car--intimidating but rewarding when you get it right.

So I've a snapped a couple photos to give you an idea what we're dealing with. The first two, are just to get you oriented. And then I took some close-ups so you can see how tight the space is.

If you look above where the hose are bolted to the bell housing, and above and adjacent to the steering coupler, you can see the starter. Then above and adjacent to that is the supercharger muffler and supercharger.

So the question is, how do you get it out?

What I know is, the intake muffler DEFINITELY has to come out, since it would not be possible to get the starter out even if you managed to miraculously unbolt it.

So how do you get the muffler out....does the whole supercharger come out too?
Or is there a another way to squeeze out the starter?

Sorry the first two photos I posted, posted upside down for some reason, which is extra confusing. We're on the left-side/driver's side. So the top of the photo, is the bottom of the vehicle in those first two.

You don't need to remove the super charger but you do need to remove the steering column coupler I believe. To get the air filter muffler out you must remove the air cleaner housing along with the computer etc. The hardest part is to get the hose clamp undone to the muffler btw. You will need one of these tools.

http://www.amazon.com/OTC-4525-Cable-Type-Flexible-Pliers/dp/B000F5JM0O/ref=sr_1_1?ie=UTF8&qid=1464057468&sr=8-1&keywords=hose+clamp+tool

Let me know how it goes

I got the tool, but where is the clamp are you talking about? The starter is behind and below #100 in the picture.

http://www.mbpartsworld.com/showAssembly.aspx?ukey_assembly=1073214&ukey_product=7766625