A/c through Defrost (77 280SE) - Mercedes-Benz Forum

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post #1 of 5 (permalink) Old 05-10-2014, 11:04 AM Thread Starter
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A/c through Defrost (77 280SE)

If the air compressor is running and clutch engaged, should cold air come out of the vents when it is in defrost mode?

Yes it is servo failure but right now the only mode that works is defrost.

So should cold air come out of the vents when the defrost is on?

So if cold air should be coming out of the vents when the compressor is on in defrost mode I would know if I need to charge the A/c.

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post #2 of 5 (permalink) Old 05-10-2014, 11:35 AM
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I'm not familiar with this model, but on 124s, defrost is the default vent when the climate control fails. If you think about it, this makes sense, as you'd want defrost to work no matter what as a safety concern. Does this have the Type II Chrysler climate control?
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post #3 of 5 (permalink) Old 05-10-2014, 05:39 PM Thread Starter
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I replied but don't see it. ONly the defrost works the servo does not.

But the compressor is on and the clutch is engaged because I connected it to the positive terminal of the battery.

With the clutch engage and defrost on should the air be cold coming out of the defrost?
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post #4 of 5 (permalink) Old 05-10-2014, 07:25 PM
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You have the evil servo system, you currant problem is most likely the amplifier but could be vacuum issue, foam sensor tube, servo, aux water pump, vac pod...or any combination of them.

Have you done any work on the system? What does your servo look like? Aluminum or bakelite?
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post #5 of 5 (permalink) Old 05-12-2014, 09:25 AM
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when you put defrost on the a/c comp will be on at all time to dry the air that is blown on windshield . this climate control system is a nightmare [ chrysler design ] . usually the vacuum system in dash goes bad [ vacuum elements ] .before jumping into this find a used book on ebay for the climate control system .
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