Last night when i started car and turned on heater i got nothing. On way to work i noticed i got a little heat from side vents but that was it.Needless to say a cold ride.This morning when i got out of work and had some light this is what i noted. Fan blower on high the air came from dash vents and top but air was cool. When i put it on auto no air from anywhere and the air circulation switch started blinking and matching clicking in a wierd sequence.Anybady have exprience with this? getting a little cold and i have a long drive everynight.any help ould be apprecated. THANXX

Marvin, that's some weird symptoms; but try the simple stuff first.
Check the water monovalve to see if it is clicking on/off to allow hot water to the heater. do you know where/what it is? It's a little electric solenoid with several water hoses running to it, just in front of the windshield on the passenger side. If you have the car running and the heater on, you can put a finger on the top of the valve and feel it click on/off every few seconds.
And, the hoses should get warm. They are pretty easy to fix, there is a kit.

Check the vacuum to the climate control system. Easiest way to confirm is to shut the engine off, then turn on the key and adjust the climate system hottr or colder, or turn on the recirc button, you should hear the doors move behind the dash if you have good residual vacuum.

If you are hearing a clicking sound from near the radio, it's probably the vacuum switching valve manifold, trying to control the air doors. This could be an indication of a faulty controller, or one of the solenoids in the manifold could be out.

Try a couple of things and get back with more symptoms.

The monovalve is the #1 culprit in the heating system, so check it out first.

DG

I stopped driving the car for awhile. I took it the other day to get tree and the air was hot again. Went to take to work the other night and absolutly nothing - no fan or anything. Ok this is what i noticed whenever the ambient temp outside is below 20-25f then i have nothing but above 35f everything works.
If the mono valve is rt in front of the battery then its getting hot water when warm - didnt feel any clicks tho. My other merc is fine in cold weather, is this a common thing for the 124s?
thanxx

No, it's not. Look in the DIY Links by Parts section "Climate Control" for more help.

I had the same problem last year. It was weird. The recirc light would be on and there was a clicking noise just like you described. I replaced the climate control push button unit with a used one from e-bay ($40) and everything has been fine since. It takes about 15 minutes to swap out the control unit.

Pete

Another place to check is the blower regulator.

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