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Marty
Marty, Mercedes Technician
Category: Mercedes
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Experience:  Bosch Certified Master Tech. Over 35 years experience.
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1989 300E: new compressor, is dripping heaps..high side..vents inside

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Have a 1989 300E and the a/c is very poor inside, have replaced tx and dryer, recently also had new compressor, is dripping heaps of water under the car but the high side pressure seems very high 350psi? maybe 15Deg at the vents inside?

eurotec :

Hi, what is your low side pressure? How much refrigerant was put into the system? Are you using R134a? Is all of the air blowing out the proper vents?

JACUSTOMER-c02th7aq- :

Hi, Low side is sitting at 27psi -in australia thats about were most cars will normally sit, but the high side with only 500grams ( about 15oz) was going to 300psi, i replaced the dryer and tx, blew through the evap and regassed now to 850grams - just short of 30oz and the pipe out of the tx is cold to touch and the car is dripping water but the temp inside is very poor, R134a

JACUSTOMER-c02th7aq- :

The vents dont feel great but plenty of air

eurotec :

If you only have 15oz in the system that is not enough for the system to blow cold.

eurotec :

Is the condenser fan working?

eurotec :

Never mind

eurotec :

I see you are up to 30oz now

JACUSTOMER-c02th7aq- :

Yes condencer fan and engine fan working - clear condencer and radiator

eurotec :

Is the condenser fan blowing in across the condenser?

JACUSTOMER-c02th7aq- :

Yes - condencer fan is blowing from front to back, that is exactly what it shows on the gauges like- no fan but the engine and electric condencer fan are ok

JACUSTOMER-c02th7aq- :

I ruled out any sensors as the compressor is operational

eurotec :

Is the high side pipe to the expansion valve hot?

JACUSTOMER-c02th7aq- :

Yes, Hot in and not as cold as I would expect out but it is cold enough to have moisture condensate on the low side out to the compressor.

JACUSTOMER-c02th7aq- :

Heater tap has been blocked off.

eurotec :

Have you flushed the entire system?

JACUSTOMER-c02th7aq- :

Not with fluid, I blew through with compressed air today when I put the tx and dryer on to make sure there was no blockage but have not flushed out. do you think a blendor motor could cause it- maybe lack of air through evap- but then it should freeze and have a low suction I thought? would you agre that it should not be a sensor fault?

eurotec :

Yes there are no sensors or blend doors in this system that will cause the fault.

eurotec :

I'd consider plugged evaporator fins as a possibility.

eurotec :

That would account for the condensate.

JACUSTOMER-c02th7aq- :

Can you get in any were to see the side of the evap?

eurotec :

Not without removing the blower motor.

eurotec :

Have you tried another expansion valve?

JACUSTOMER-c02th7aq- :

is that a dash out job? to get to the blower? When the new compressor was done 3 month ago there was a new dryer and tx fitted, I have since recovered and regassed 3 times with the old tx and then replaced with a new tx and dryer today ( that had a different number on it ) and regassed again- when the compressor was done the system was working

eurotec :

It's dash out to replace the evaporator but the blower motor is removed from outside the car. You need to remove the wiper system to get to the blower motor.

JACUSTOMER-c02th7aq- :

Hmm , I might try that tomorrow and have a look at the evap, that would be good to see it while the car is running so I can get an idea if it is cold - my only other thought is maybe a oil log in the condencer not allowing enough cooling ? do you know the correct gas level for them? I have seen 32.5oz, about 950g

eurotec :

1100 grams was the original R12 charge. You might try adding a bit more refrigerant. Just watch your high side.

JACUSTOMER-c02th7aq- :

Yes thats why I stoped at 850g- its just to high for my way of thinking, most cars here run about 27psi/230psi

eurotec :

I have seen them up over 300 psi before. If I got to 350 psi I might be a little concerned.

JACUSTOMER-c02th7aq- :

hmm, I will try more gas first as it is already at 850, failing that I will look into the evap and last resort remove the gas yet again and flush the condencer, I have had it in my head poss blendor but when I think about it , it should freeze if there was no air flow. Thanks for your time 9521 accepts- you must spend alot of time on here? Thanks

eurotec :

You're welcome. I agree with that line of thinking.

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