W202 Aircon Duff

[Dave Bailey]

Hi All,

Does anybody know at what ambient air temperature the A/C is supposed to start working at? Although the outside temperatures aren't that warm at the moment (12 - 14c), I'm pretty sure that the A/C should work anyway. I've read on other threads that the compressor should run all the time, irrespective of outside temperature. My compressor doesn't seem to cut in, so I have convinced myself that there is a fault. Is there a fairly easy way to check the system? It would be good to verify the problem before I call an A/C specialist.

Thanks in advance,

Dave

 

[KLee]

Do u know whether you have MB or Diavia or aftermarket a/c?

 

[Dave Bailey]

Do u know whether you have MB or Diavia or aftermarket a/c?

It's the MB A/C. I just popped outside for a quick look at it. I think there's a leak in the system somewhere. There is a cylindrical canister mounted on the passenger side of the engine bay near the headlight. There is a sight glass on top of the canister. It appears to be empty

 

[jimmy]

The sight glass is an indicator of the oil in the sytem and not the A/C gas, when running you should see a fluid 'bubbling' in the sight glass.

The A/C should run whenever it's switched on irrespective of outside temperature. I think there is a pressure sensor that stops it working if there is low gas pressure.

 

[1998K]

The sight glass is an indicator of the oil in the sytem and not the A/C gas, when running you should see a fluid 'bubbling' in the sight glass.

no the sight glass indicator is relevant to the gas! this for sure!

Oil are filled in the circuit together with tracking fluid when the re-gassing is done. But the circuit is the same of the gas.

As far as the sight glass criteria, it's quite an interpretation, I don't know well, I've read on Haynes Manual that if you see bubbles, AS STARTED the AC system with idle engine you have to re-charge the system.

But I can't personally confirm.

Marco

 

[Dave Bailey]

no the sight glass indicator is relevant to the gas! this for sure!

Oil are filled in the circuit together with tracking fluid when the re-gassing is done. But the circuit is the same of the gas.

As far as the sight glass criteria, it's quite an interpretation, I don't know well, I've read on Haynes Manual that if you see bubbles, AS STARTED the AC system with idle engine you have to re-charge the system.

But I can't personally confirm.

Marco

I can't see any fluid at all in the sight glass, just what looks like a shiny crinkled washer shaped piece of metal. It all points to a leak.

Anybody know of a trustworthy A/C specialist in South Essex?

 

[nickmann]

The compressor should run if you turn the dials to blue and turn economy mode (EC) off. It will turn on and off as necessary to maintain the temp you have set, but setting full blue will guarantee that it is being asked to run.
I believe if the gas level is too low then the EC light will not go out.
Perhaps your sight-glass is 100% full and not empty. I know on mine it was hard to tell.

It is hard to know how the system is performing at this time of year. It has sensors both outside and inside, and if the ambient temp is cool then it does not blow so cool. I got concerned about mine last year as it didn't seem so cold, but I had it checked over and it got a clean bill of health. Later, in the summer, it was icy!! There is no substitue for a check by some-one with the right equipment.

 

[panason1c]

Due to the refridgerant being clear it is hard to tell whether the sight glass is full or not but the procedure, as i know it, for checking the refridgerant is...

1/ With the engine NOT running, look at the sight glass

2/ While still watching the sight glass have someone start the engine and turn on the A/C

With the engine at idle you should see a rush of bubbles for a couple of seconds or so and then the bubbles will disappear and the sight glass will be completely clear with no bubbles if the refridgerant is fully charged.

If you continue to see bubbles then that indicates that the system is low on refridgerant and needs a recharge....

This is all assuming that the compressor is engaging in the first place when the A/C is turned on .....if the system is too low on refridgerant a low pressure cut-out switch will prevent the A/C compressor from operating to protect the system.

 

[Dave Bailey]

The compressor should run if you turn the dials to blue and turn economy mode (EC) off. It will turn on and off as necessary to maintain the temp you have set, but setting full blue will guarantee that it is being asked to run.
I believe if the gas level is too low then the EC light will not go out.
Perhaps your sight-glass is 100% full and not empty. I know on mine it was hard to tell.

It is hard to know how the system is performing at this time of year. It has sensors both outside and inside, and if the ambient temp is cool then it does not blow so cool. I got concerned about mine last year as it didn't seem so cold, but I had it checked over and it got a clean bill of health. Later, in the summer, it was icy!! There is no substitue for a check by some-one with the right equipment.

I've tried running with the dials set to blue. EC mode is always off, as I like to leave the A/C on all the time. The compressor does not cut in at all. Interestingly, I have tried toggling the EC button. This makes no difference at all, though I have noted that the EC light does go on and off. I now regret not paying closer attention to all this last year because I can't remember if the compressor ran at outside temperatures similar to the current ones or not. Must be getting old.... Trouble is that because I've had a fair bit of grief with this car, I'm now a bit paranoid about it and tend to notice every slight thing going on. Perhaps I should just bite the bullet and get a specialist round to have a look anyway...

 

[Dave Bailey]

Due to the refridgerant being clear it is hard to tell whether the sight glass is full or not but the procedure, as i know it, for checking the refridgerant is...

1/ With the engine NOT running, look at the sight glass

2/ While still watching the sight glass have someone start the engine and turn on the A/C

With the engine at idle you should see a rush of bubbles for a couple of seconds or so and then the bubbles will disappear and the sight glass will be completely clear with no bubbles if the refridgerant is fully charged.

If you continue to see bubbles then that indicates that the system is low on refridgerant and needs a recharge....

This is all assuming that the compressor is engaging in the first place when the A/C is turned on .....if the system is too low on refridgerant a low pressure cut-out switch will prevent the A/C compressor from operating to protect the system.

Looks like it's pooped then. The compressor doesn't engage at all. Having said that, I have not as yet observed the compressor clutch whilst somebody else starts the car. So I don't know if it cuts in, then drops straight out again. I'll have another look....

 

[jimmy]

Perhaps I did not explain it clearly.

The fluid you can see in the sight glass is the lubricant and not the gas. Obviously if you have low gas it wont get pumped around the system and wont carry the lubricant around so no bubbles would indicate that the A/C is not circulating.

If you get somebody to switch the A/C on whilst looking at the compressor, you should see and hear the clutch on the front clicking in and out. Also feel the metal pipes to see if there is a difference in temperature.

 

[panason1c]

Found the following article....

http://www.procarcare.com/icarumba/...edia/icar_resourcecenter_encyclopedia_ac3.asp

The sight glass is normally located in the head of the receiver/drier. The receiver/drier is not hard to locate. It's a large metal cylinder that looks something like a fire extinguisher. Sometimes the sight glass is located in one of the metal lines leading from the top of the receiver/drier. Once you've found it, wipe it clean and proceed as follows:

With the engine and the air conditioning system running, look for the flow of refrigerant through the sight glass. If the air conditioner is working properly, you'll be able to see a continuous flow of clear refrigerant through the sight glass, with perhaps an occasional bubble at very high temperatures.
Cycle the air conditioner on and off to make sure what you are seeing is clear refrigerant. Since the refrigerant is clear, it is possible to mistake a completely discharged system for one that is fully charged. Turn the system off and watch the sight glass. If there is refrigerant in the system, you'll see bubbles during the off cycle. If you observe no bubbles when the system is running, and the airflow from the unit in the vehicle is delivering cold air, everything is OK.
If you observe bubbles in the sight glass while the system is operating, the system is low on refrigerant. Have it checked by a professional.
Oil streaks in the sight glass are an indication of trouble. Most of the time, if you see oil in the sight glass, it will appear as a series of streaks, although occasionally it may be a solid stream of oil. In either case, it means that part of the charge has been lost.

 

[Dave Bailey]

Perhaps I did not explain it clearly.

The fluid you can see in the sight glass is the lubricant and not the gas. Obviously if you have low gas it wont get pumped around the system and wont carry the lubricant around so no bubbles would indicate that the A/C is not circulating.

If you get somebody to switch the A/C on whilst looking at the compressor, you should see and hear the clutch on the front clicking in and out. Also feel the metal pipes to see if there is a difference in temperature.

I'm pretty sure that there has been a leak. I've tried toggling the EC button whilst observing the compressor pulley/clutch assembly (not on my own, my arms aren't that long... <g>). The clutch doesn't engage at all. I do still need to have a quick look at it whilst somebody else starts the car, just to be thorough. Things do seem to be pointing to a loss of refridgerant. I just hope it doesn't get too exbenzive....

 

[Dave Bailey]

Found the following article....

http://www.procarcare.com/icarumba/...edia/icar_resourcecenter_encyclopedia_ac3.asp

The sight glass is normally located in the head of the receiver/drier. The receiver/drier is not hard to locate. It's a large metal cylinder that looks something like a fire extinguisher. Sometimes the sight glass is located in one of the metal lines leading from the top of the receiver/drier. Once you've found it, wipe it clean and proceed as follows:

With the engine and the air conditioning system running, look for the flow of refrigerant through the sight glass. If the air conditioner is working properly, you'll be able to see a continuous flow of clear refrigerant through the sight glass, with perhaps an occasional bubble at very high temperatures.
Cycle the air conditioner on and off to make sure what you are seeing is clear refrigerant. Since the refrigerant is clear, it is possible to mistake a completely discharged system for one that is fully charged. Turn the system off and watch the sight glass. If there is refrigerant in the system, you'll see bubbles during the off cycle. If you observe no bubbles when the system is running, and the airflow from the unit in the vehicle is delivering cold air, everything is OK.
If you observe bubbles in the sight glass while the system is operating, the system is low on refrigerant. Have it checked by a professional.
Oil streaks in the sight glass are an indication of trouble. Most of the time, if you see oil in the sight glass, it will appear as a series of streaks, although occasionally it may be a solid stream of oil. In either case, it means that part of the charge has been lost.

That's a very useful link Panason1c, thanks.

 

[Stratman]

Anybody know of a trustworthy A/C specialist in South Essex?

Have a look here. There are links to recommended specialists about threequarters the way down the page.

 

[Dave Bailey]

Have a look here. There are links to recommended specialists about threequarters the way down the page.

John the aircon guy has pointed me to a local specialist. The local chap is going to look at the problem on Friday. At the moment he thinks it will just need a recharge (£60.00 all in). I'll post an update after he's done.

John sent me this interesting link:

www.airconditioningforcars.co.uk

It's full of useful stuff. Incidentally, I can only say hats off to John for responding to my query in a very positive and timely manner. A rare thing these days, especially considering that he's not going to earn from my problem.

Cheers,

Dave

 

[Dave Bailey]

W202 Aircon Fixed

Well, the aircon is now fixed.

The problem was a leaky condensor. The condensor had rotted through, caused by a build up of crud between it and the electric fan housing. This is a common failure mode and has been described on this forum in detail before.

The cost was £350.00 all in, which seemed fair to me. The work was done by Mike Bonny of Bonair, http://www.bonair.co.uk Bonair are based in Rayleigh, and cover all of Essex.

Rgds,

Dave