About a year ago my center vents stopped blowing air conditioning. It is HOT again in NC.

Last week I turned the ignition key to let the glow plugs cycle and I heard what sounded like a relay shorting out - clicking - click - click and when I started the car the sound stopped. And guess what!!! Those center vents started blowing ice cold air!

Well now it is a week later. I just ran the car up to the store. When I got in I heard the same clicking. Then the center vents quit working.

I am guessing climate control push button unit. Beckman Technologies in Durham rebuilds them with an all new board and all new components for $275 for exchange. One year warranty.

Let me know if you have other ideas on fixing this. I think my diagnosis is correct without having to tear out the dash.

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1982 300SD Light Blue
2002 Honda Accord SE
1974 Toro Wheel Horse Tractor
2000 Toyota Tundra Pickup

I fully expect that you have a flaky ignition switch. The next time the fan doesn't blow after starting the car, wiggle the ignition switch and see if it comes on. BTDT.

Good luck with it,

Reverend,

I have recently replaced the CCU on the SDL with an e-bay unit from a 1991 vehicle. Although it has fixed my issues with the compressor engaging in the economy mode, it too decides to do the click-click-click-click routine every so often.

What I have experimented with, and it has been somewhat successful, is to turn the temperature wheel all the way down to the minumum value. It appears that the CCU is "confused" as to whether to supply cool air or warm air, if the temperature is close to the setpoint. Who knows what the real deal is.

But, this has been helpful recently in getting it to work without the relays clicking incessantly.

If the relays are clicking, I don't think the ignition switch is the culprit.

I am not sure Brian how the ignition switch would be the culprit? Although my buzzer did quit working a while back. I just decided not to fix that.

Give me your technical know how on this one!

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1982 300SD Light Blue
2002 Honda Accord SE
1974 Toro Wheel Horse Tractor
2000 Toyota Tundra Pickup

Larry correctly noted that the ignition switch sometimes fails to make complete contact and you might see intermittent action of the blower. Sometimes the blower works, sometimes it does not.

After thinking about it a bit, I suppose that it is possible that the ignition switch could be the culprit with the clicking relays, if this situation is simultaneous with an intermittent blower.

In my case, the blower is not intermittent, however, the relays do click away at times, so, the symptoms are not identical.

It's easy to check. When the problem recurs, just fiddle with the ignition switch a bit and see if there is a change in symptoms. If so, then the switch is highly suspect.

I thought the problem was with the center vents failing to open? that sounds like a vacuum pod issue to me.

Were the other vents blowing cold air when the center vents weren't working?

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'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E