recirculate 80% fix - PeachParts Mercedes-Benz Forum

Johnhazen · #1 07-18-2007, 06:32 PM

Does anyone know how to revamp the a/c system on my 560SL 1989 so that no outside air gets in? In Phx AZ even 20% is too much when the outside air is 110 degrees.

okc329 · #2 07-18-2007, 06:44 PM

the problem is that your A/C system is not working as efficiently as it should.
What are the temperatures from your outlets when in outside and re=circulate mode? Maybe the the damper doors aren't closing as much as they should for the re-circulate mode. Maybe you have engine coolant flowing thru the heater core when it should not.

Johnhazen · #3 07-20-2007, 03:56 PM

From what I have been able to gather the system is designed to allow 20% fresh air even when in recirculate mode. I have read about a modification for a 123 chassis, but that does not seem to be applicable to the 560SL. I have also read that when you rotate the temp. wheel to min (to where it clicks) you would get full recirculate. I do wonder however if that means 100% recirulate or rather the 80%/20% mix. I also do not see much of a change between having the recirculate button on or off. There are two hoses going to the back of that switch, but there are 3 holes and I am not sure if I have the hoses in the right holes. My shop manual a/c vacuum schematic is not clear on which holes to use. As far as the vent temp, I do not have a thermometer to measure it, but it is not really really cold like my other two cars. Only maybe around 65 degrees as a wild guess. I have replaced the mono valve last winter as I was not getting heat. That did not look bad, but I did get heat afterward.

david s poole · #4 07-20-2007, 04:21 PM

the fresh air doors are in front of windshield.with hood up look and you will see three little plastic pops.you will need to find a small punch to pop out the centre of these and then the balance comes out forward.once you remove these grills you can see the air doors.now if you cut some aluminum plate to fit and then pop rivet them down[with black sealant around the edges]paint them black and replace the grills,you will have cut off the fresh air completely.

brewtoo · #5 07-20-2007, 05:59 PM

If that car is like the others, it uses vacuum pods to operate the various flaps and vents. The 124 has two pods on the recirculate door. Your pods may be leaking on a car that age. If so, you may not really be getting any recirculate at all.