1994 Mercedes Benz E420 AC Intermittent

Tiny
GRP914
  • MEMBER
  • 1994 MERCEDES BENZ E420
Air Conditioning problem
1994 Mercedes Benz E420 V8 Two Wheel Drive 92,000 miles

My air conditioning is intermittent. I have had the AC compressor and dryer, the control panel, the aux fan resistor and the manifold temp sensors replaced.
The AC may run for a while and then quit or it may not run at all or it may work fine all day. When the car is shut down and left off for a while the AC will most often come on and run for at least a few minutes after start. I have had the Freon level checked and the high end pressure is normal when the system is running.
Please help!
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Tuesday, July 21st, 2009 AT 6:52 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Is it the fan that stops or does it start blowing warm air?
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Tuesday, July 21st, 2009 AT 11:50 PM
Tiny
GRP914
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The blower remains in it's last selected position the compressor shuts down and the system blows warm air.
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Wednesday, July 22nd, 2009 AT 7:43 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It sounds like the cycle switch may be bad. THat is where I would start.
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Wednesday, July 22nd, 2009 AT 11:24 PM
Tiny
GRP914
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What and where is the cycle switch?
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Thursday, July 23rd, 2009 AT 8:18 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
THe cycle switch determines how often and when the compressor will engage. Honestly, at this point, I really feel a tech needs to look at it.
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Thursday, July 23rd, 2009 AT 12:53 PM
Tiny
MATTCHEWMAN
  • MEMBER
My e420 had the SAME EXACT problem it's like you were discribing my cars issue.

I took the A/C condenser fan shroud off and found 3-4 inches of dirt packed into the condenser and between the condeser and the fan shroud. First I used a shop vac to suck the dirt out(you dont want to push the dirt further into the condenser) then i used a hose to rinse it off. Be carefull not to bend the fins on the condenser. When I did this it was a conplete difference, it works great now.

In the first pic you can see what parts I had to remove. You can also see a small amount of the dirt that had fallen out and onto the ground and the plastic under skirt. The second one you can see the cleaned condenser with water driping off.

Total of things to remove: Clips from top of Radiator, Clips from top of A/C condenser, Horns, body colored support beam in front of the condenser, front bumper, front of plastic underskirt, 2 Bolt's that hold the coil loop in front of the A/C condenser, condenser fan shroud(Difficult), condenser fan.

If you do all this I sure hope it fixes your problem. Because it's a real task.

It's important to note that the dirt was packed in th bottom and was not visible until the fan shroud was off.


http://www.2carpros.com/forum/automotive_pictures/402439_Dirty_condenser1_1.jpg



http://www.2carpros.com/forum/automotive_pictures/402439_bottom_of_ac_condenser1_1.jpg

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Saturday, August 29th, 2009 AT 10:29 AM

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