HELP air con prob

[e220man]

No cold air coming out of vents,air con drive belt working,tension on belt ok,revs drop when i switch air con on, im i right in saying the compressor is ok?the condenser pumps i.e the two pumps the smaller pump is hot as it should be but the larger pump is hot when im sure it should be cool, what could this signify?,could it be that i need my unit gassed up?if so how much will this cost?. Im i looking at a service and fluid change?Any suggestions would be helpful as im in the dark when it comes to air con units. E220 salon 95 plate. CHEERS .. e220man...

 

[molar]

your air con sounds as if it needs the refrigerant re-charged or re-gassed. MB dealer would charge about £120 because they say it needs what they call an Air Con service.

 

[guydewdney]

most air con shops charge about 70 odd quid... try stiff nipples uk... get dye added, then you can check for leaks.

guy

 

[molar]

Well, if you know for sure it is the refrigerant then going to an aftermarket shop to get it re-charged is fine. But the difficulty is when you don't know what is wrong with it. Hence I had to go to a MB Stealership to have it all checked, and re-charged.

 

[Keith]

aircon

I had similar symptoms

the recharge may solve it and it needs doing from time to time anyhow so you may as well. The cost from an independent should be under £100 , my last was £50. dont use a stealership this is a standard operation like having a new tyre or exhaust.

if there is no improvement there are some other inexpensive elements that you can try before getting into the heavy cost items. I am thinking of cabin and heater temp sensors and the small fan that pulls the air across the cabin sensor. Dont charge into expensive component replacement without looking at these. I learnt the hard way and spent a total of £750 on parts and labour with no improvement . I then discovered it was the air sensor fan which cost £40 and took me 30 mins to replace.

Let us know how the recharge goes.

Keith

 

[npilko]

I am having a similar problems with my w140 s-class. I had the air con re-charged, the engine revs dropped but the air con still refuses to pump out cold air.

Where about are the sensors that may solve the problem?

Thanks

 

[guydewdney]

the little cabin sensor is the grille between the interior front dome lights...

pull off back edge of lens, remove bulb, remove screw - repeat other side - assy then drops out.

also look at the diagnostic stuff on the air con controller...
http://www.continentalimports.com/ser_ic40142.html

 

[Keith]

easy way to check

the original question was about a 95 e220 which i am not sure of the body probably w210 . My experience is a W124 however I think the air con control is very similar.

The cabin temp sensor is unlikely to have failed itself however it only costs around a £5 so you may as well replace. The more likley problem is the fan than sucks air across the sensor which in my case failed resulting in the sensor losing the true cabin temp. The easy way to check is to pull tube off the black plastic sensor assembley and let the assembly dangle into the cabin. Drive around with it dangling and see if it regains control of the aircon (basically by dangling it you dont need the fan to pull the air through). If this cures the prob then its the fan which is located (in a W124) inside the dash on the other end of the black tube just below the passenger window air vent. Take glove box/airbag out to get at it.

Other sensors can be found behind the aircon control unit in the dash . These monitor the air coming into the cabin but I think it less likely this is the prob but they are fairly easy to get at.

good luck
:wink:

 

[steve moores 1]

E220 Air Con Prob

Gents

Staying with the E220 (coupe, in my case) theme. The air con on mine blew warm air when set on the coldest setting. I had it re-gassed and the compressor overhauled. However, now the air is so cold that after a 1/2 hour or so, ice begins to form on the vent grilles. 8)

Unfortunately, after an hour or so from switching on the air con the volume flow rate drastically reduces regardless of the temperature setting or the drier & recirc settings, i.e. when the fan is set to speed IV, the flow rate is that of speed I. When set on speed I, a very feable trickle of air appears. This happens regardless of the temperature, air direction (screen / floor / front vent) setting or indeed the car's fan (when switched on economy - as opposed to air con) setting.

The car doesn't have a pollen filter and the fan motor keeps running (implying that the fuse holder gremlin can't be to blame) but the sypmtoms imply something somewhere is physically restricting the air flow rate; perhaps a flap is dropping inside the fan or a sensor somewhere is directing a reduction in air flow?

If you could advise, I'd be very grateful.


Regards


Steve Moores

'95 E220 Coupe

 

[guydewdney]

maybe the air passages are filling with ice

 

[Keith]

the problem sounds like the fan fuse gremlin

I had just the same symptoms with the flow rate and it turned out to be the fan fuse after all.

What happens is it heats up more on higher settings and then as the holder melts the fuse contact becomes poor increaseing the heating effect and reducing the current to the fan giving low performance on high setting etc. eventually the fan dies completely. Have you tried wedging a ball of cooking foil on one end of the fan fuse to (temporarily) improve the contact and if that results in success the you know its the melting fuse holder syndrome?

Keith

 

[Mr Fridge]

Ice on vents, air flow quantity reduces after running for a while, sounds to me that the evaporator is icing up, could be a faulty mechanical de-ice thermostat or faulty NTC probe attached to the evaporator if electronically controlled. From experience I have worked at car sales garages who have had electrical faults on the air con system or electronics and to bodge it they take a live feed from the battery to a switch on the dash board or to the original a/c switch and fit a relay and then the direct feed from the relay goes straight to the magnetic clutch thus by passing all the controls and protection devices, bad I know but it goes on a hell of a lot on used car sales.

 

[steve moores 1]

Air Con

Thanks for your assistance Gents

I'm not convinced (although I know it's a popular theory, so I'll still check it) with respect to the fuse. I'm not totally sold simply because once the flow rate has slowed it stays there (although I don't think I mentioned that earlier).

With respect to "Mr Fridge"'s theory. Could this also explain when the system is set on the heating only cycle and not just on cooling? Are there any obvious signs one should look for to spot such a bodge?


Thanks once again for your help.



Regards


Steve Moores

'95 E220 Coupe

 

[Mr Fridge]

A bodge can usually be spotted by tracing the wire from the magnetic clutch, if bodged it will be a different non standard colour and not in the harness and probably connect to a non genuine relay.

 

[e220man]

Thanks lads and lassies...

Air con prob now solved, all it was was a burnt out wire and no gas re-charge £70,and labour to change the burnt out wire. thank god no major costs, all cool and ice cold for £115. So a BIG THANKS to u all for replying with advice, contentment again and happy merc motoring. Just came back from motor show yes the new slr is the bizz with a cool 623 BHP and a hot price tag of over 300k, the whole car is orgasmic but what a struggle to get in and out of the car,so low with little space for entry.did anyone else notice this if u were there???..... Regards E220man... :lol: