w124 climate control

[coert]

Hi Guys

Great forum!!

Please help me out

W124 with faulty climate system, interior fan does not work at any speed,recirculation function works,compressor does not engage when selecting EC switch, permanent hot air from the centre air vents.How can I test the the compressor function from the climate control module and can I bypass the gas pressure switch for a few moments to see if the fault originates from low gas pressure.

[brewtoo]

While I don't know what the cause is, I cannot imagine that low gas pressure is the cause of these problems.

The control unit itself would be more suspect.

Compressor is not supposed to engage when you press the EC switch.

What due you mean exactly by interior fan? The blower? The aspirator?

[softconsult]

Once again, poster provides no information about the car. Like Model, Year, mileage and maintenance history of Climate Control related components. Also whether the car is R12 or R134a.

I have been through the climate control problems on two different 124's and it really is not so simple. Complicated system. I experienced three compressor failures over 225K miles. My solution was, in both cases, to take it to the MB pros rather than attempt my own amateur hour diagnosis. I needed the car back, and you need all the A/C recycling equipment to do it correctly. Roughly, $1200 to $1500 fix all three times.

PS: I continued to use the original R12 on these two cars, '90 and '92.

Hopefully the solution to your problem will be less expensive.

Steve

[coert]

Thanks for the reply

My apologies for not supplying enough info on the vehicle.It is a 1991 w124 230e automatic with 460 000KM on the clock.

I have in the mean time sorted most of the problems.

1- Gas pressure was slightly low.
2- The fan I referred to was the interior fan,not aspirator. The switch contacts was dirty. I cleaned these and it is now working 100%
3-Replaced faulty climate control PC board behind centre console.
4- Replaced stuck heater valve

All seems to be working fine.

Thanks for all the input

[coert]

Hi there

I would like to know if R12 and R134 gas can be mixed in a system. My system recently had to be "topped up" and the technician assured me that he can top the R12 system up with R134a gas. Is it safe to do so?

Thanks

Coert

Originally Posted by coert

Hi there

I would like to know if R12 and R134 gas can be mixed in a system. My system recently had to be "topped up" and the technician assured me that he can top the R12 system up with R134a gas. Is it safe to do so?

Thanks

Coert

NO!

Don't mix R12 and R134!

[softconsult]

I would run away from that technician. He is clueless on A/C and probably on other mechanical topics.

Steve

[coert]

Thank you

I am going to break that technicians left pinkie !!

How do I correct this mixed gas problem?

[OzC36]

This sibuadvancetech guy in Malaysia seems to have a good grip on Mercedes A/C systems:

http://www.mbcnsw.org.au/forum/index.php/topic,1640.0.html

[brewtoo]

A big part of your problem, if this has already been done, is that the R12 oil is not compatible with the R134 oil.

If your tech simply added nothing but a bit of R134, perhaps you can get away with evacuating the system and recharging with the proper R12 refrigerant.

[davidmash]

A bit of a hi-jack if no one minds.

I have a 1995 E300D with R134.

I have a defroster Question.

Is there a way to control the fan speed manually and the temp manually? When my wife hit the Defrost and the unit is in "auto" mode it burns her out of the car. I was reading the manual and there does ot seem to be a way to direct air just to the windshield and to be able to control the fan and temp.

I would think there should be some way to direct warm (not hot) air to the windshield at a moderate blower speed.

Thanks

[coert]

The tech (lets not call him a tech anymore) also added uv dye to check for leaks. I know on my vw polo the agents have an automatic device to evacuate both gas and oil in the system.Does Mercedes use a similar system and should I have other components replaced in the system ( for the technicians bill of coarse!

Also,If the system is changed to R134a what components needs to replaced as I believe this gas operates at a higher pressure?

Yeh lots of questions, buts that the only way for me to learn.

Thanks

[Mike Freeman]

In answer to the question about defrost,There is no way to adjust temps. when def. is selected.
The hot water valve is open and the compressor is on to "dry" the air.
After the window is cleared use the button with the UP arrow to maintain controlled heat with dry air.
Mike