If my front windshield is recieving cold air, when the a/c is on, does that mean that I need to replace the fresh air pod, or the defroster pod?

I thought that I replaced them all last summer, but I must have missed one.

Has anyone ran into this same problem before?

1983 300CD is the car.

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Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.

That may be indicating a total loss of vac. Check the vac line manifold and individual valves for seal. I have seen similar symptoms with a line coming completely off a valve!

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1983 Mercedes 300SD
1987 Mercedes 300SDL
2001 VW Passat 2.8 AWD
2007 OM642 Jeep WK 4x4

Draw a vacuum, from the engine compartment, on the line that feeds the interior. I found that it was not 'holding' a vacuum - but - if I repeatedly pumped a vacuum - my center vents came back to life for a short period of time. Further troubleshooting showed I had a problem with my headlight adjusters.... Disconnected the headlight circuit and the interior started to work normally..........

Mighty-Vac to the rescue........................

Stephen

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98 K2500 Suburban 6.5 Luxo Barge

"We cannot change the wind - But we can adjust our sails"

If it is the defroster pod, it's located on the driver side above the footwell. It's the only one with two vac lines going to it. One from underneath and one from the side. Mine had a rip in the diaphragm for the line that fed it from the side that is split off the center vent pod line. Oredered it and it just came in last week, but I left it at work and haven't put it in yet.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

The way the system works is it defaults to full defrost airflow with loss of vacuum. So you either have a vacuum problem, or a bad defroster pod. It's a two-chamber pod, both chambers need to be good in order to fully close the flap and shut off the airflow when the system is supposed to blow cool air. You'll need to test the pod (both ports) with a Mity-Vac, both should hold vacuum. If not, replace the pod. If this is the one above the driver's feet, it's a real PITA to replace. I had to do it on my W123 as well.

Less likely is that the vacuum system is fine, but you have an electrical problem. It's possible that either the vacuum solenoid (behind the ACC pushbutton unit) could be bad, or the pushbutton unit itself may not be sending the electrical signal.

Start by checking the vacuum stuff first, that's more likely.

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Dave
Boise, ID
Check out my website photos, documents, and movies!

Last summer I changed the vacuum pods behind the dash, but I dont remember doing the one near the driver's right foot near the transmission tunnel.

The vacuum lines near the engine look good. I will look into the other ones. It made my windshield fog up really bad when it started raining the other night (when its hot outside).

__________________
Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.

So this is the story:

The Defroster pod was changed last summer, but the clip that attaches to the armature is broken, so it is not able to pull the flap closed. I am going to to have to like be very creative about this, but I have an idea. Ill post pics when I do it, next weekend.

My foot vacuum pod wasnt changed, but it rarely goes bad.

All others were changed.

__________________
Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.