G500 AC blowing warm

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Morpheus
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HELLoooo,

Its hot in here at the moment.

A slight problem with the AC. I will check the clutch on the compressor is free; and the system has been pressure tested and re-gassed. Any tips?

All responses greatly appreciated,

 

Morpheus. 

Pistonhead
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Re: G500 AC blowing warm

Morpheus wrote:

.......and the system has been pressure tested and re-gassed. Any tips?

My first query is if you had to re-gas why was the refrigerant lost in the first instance? - Fine that the system was pressure tested? They should be vacuum tested, if that is what you meant.

If the compressor is circulating you should be able to see small bubbles in the small window on the dryer unit. If there is no actively here the compressor is not circulating the refrigerant. You have mentioned that it blowing hot air so the internal fan is working but not exchanging heat to transfer cold air hence it looks like a compressor issue. If that has not engaged, have the high temperature sensor (100 degree switch) is working, these have known to fail.

A diagnostic reading would bring this up on a fault code.

 

Morpheus
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Re: G500 AC blowing warm

 

Thank you for the response. I have noticed the compressor head is rotating and engaged also the centre nut is rotating. I have noticed the AC indicator is on constantly and does not go off. The refrigerant was replaced and system checked as an elimination process. I will go through methodically . All remarks appreciated.

Many thanks,

Morpheus.

 

 

Arnie
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Re: G500 AC blowing warm

There is a gauge-set that you can buy (for about £80), but which any AC re-gas company should have an know how to use. These are connected to the existing ports on the system and by taking pressure readings you can tell if there is too much gas, too little gas and if the compressor is operating properly.

http://aircondition.com/tech/questions/82/Troubleshooting-with-Gauges-FAQ​

http://www.vehicleairconservices.com/page/gauge_readings​

https://www.carid.com/articles/how-to-use-an-air-conditioning-manifold-gauge-set.html​

Remove the front grill (6 x 10mm screws at the front of the engine bay) and check that the condenser radiator at the fvery ront is not blocked with mud. It should be warm/hot to the touch if the A/C is working. Generally, if the system pressure is too low or too high, the controller will not allow the compressor to run.


The other possibility for a fault can lie with the expansion valve, if it has stuck fully open or fully closed If everything else checks out, in terms of gas pressures, compressor operation, and clean condenser, then this is the last resort.

 

 

 

Morpheus
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Re: G500 AC blowing warm

 

Hello Arnie,

Thank you for your response it's really appreciated.

The following has been noted.

1. The internal A/C indicator is on all the time. Rest button.

2. The clutch is engaged all the time.

3. The refrigerant indicator in the engine bay is green and does show a bubble but not many.

4. Blowing semi warm air. As if it is trying to operate.

5. I have also noticed the two fans in the very front of the engine bay are not coming on. When I disconnected the supply to the expansion. valve one fan came on ?

Thank you once again,

Morpheus.

Arnie
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Re: G500 AC blowing warm

Older MBs were designed with having the a/c operating all the time and an EC (economy) button could be pressed to keep the a/c turned off (orange indicator). Newer cars now follow the convention that the a/c is normally off and is activated by pressing the a/c button with a green light. 

It seems strange that the cooling fans for the condenser are not working. Normally, they are two speed and the lower speed operates when the a/c is on and the high-speed is engaged when the engine temperature exceeds around 110 C.


I am not sure why disconnecting the expansion valve circuit would cause the fan to turn-on, unless you have also disconnected a temperature sensor on the same connector plug.

The a/c system has its own diagnostic codes and maybe you could try reading them with a suitable scanner. Also, there is a self-test reset procedure that can be activated by pressing a combination of the buttons:


eg: http://forums.mercedesclub.org.uk/index.php?threads/203-reset-of-blowers-and-actuators.28561/

 

 

 

 

Pistonhead
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Re: G500 AC blowing warm

I not an expert on air conditioning but if your system is gassed up and has as you report, there are some bubbles in the eye glass which is normal then to my mind; I wonder if the dyer is not effective, these can reduce the cooling effect but second this by an experts. There seem to be two schools of thought that dyers should be renewed periodically. The frequency of renewal, I have never learned so far.

Morpheus
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Re: G500 AC blowing warm

Hello Arnie,

Just got back from BOSCH Germany. They have confirmed that the condenser cooling fan passenger side (LHD) has failed. They have stated that eight hundred and seventy pounds will be the cost to fit a new one.  Any chance of getting a condenser cooling fan anywhere else?

Thanks again,

 

Morpheus.

Arnie
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Re: G500 AC blowing warm

 

Start by removing the existing one. It can probably be repaired -might be stuck or worn  brushes - or you can find an equivalent fan motor from an MB salvage (I think S-Class, or E-Cllass but other types may also work.).

Typically the fan assembly with the frame that mounts in front of the condenser is tailor made to the vehicle type, but the fans and motors themselves are pretty-much all the same (if from Bosch)  and can be replaced separately. You can find the motor with fan blades new for about £100, if not from parts salvage for much less.

for example:

https://www.amazon.com/Bosch-0130007081-Condenser-Fan-Motor/dp/B006YCMPFQ​

Also, you can look for Hella:

eg: http://www.ebay.co.uk/itm/8EW-009-158-751-HELLA-Fan-A-C-condenser-Left-/302356686249?​

http://www.mister-auto.co.uk/en/radiator-fan/hella-8ew-009-158-751_g508_a0028EW!009!158-751.html?​


Remove existing one and try to find a match.

Morpheus
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Re: G500 AC blowing warm

 

Thank you Arnie and Pistonhead,

Your response is really appreciated.

When I drove back from Bosch the A/C was blowing cold but I noticed only one condenser fan was working. I  will dismantle the fan assembled and see if I can obtain the motor or get it fixed .

Got to thank you once again,

Regards,

Morpheus.

Morpheus
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Re: G500 AC blowing warm

Ok, So it seems there is a non functioning condenser fan and it has AEG on the front of it. Bosch or Hela  compatable ? Also, when I got the vehicle back, the Bosch tekkies cleared the error codes chargeing €5.00 a code. The A/C is really working well on one fan. So I am now looking for a replacement. When I disconnected the faulty fan I made the mistake of turning the ignition on so I think its back to the fault codes again needing clearing. I think I know where I am now. All your help is appreciated. Many thanks. Morpheus.

My understanding is :-

1. Error codes due to fan malfunction need clearing.

2, I have wired a direct 12v to fan and it does not move,

3, Will extract old unit and replace.

3. Will have to pay to reset again unless there is a reset available for the A/C