Climate Control Problem- no heat at all MB 280 CE 1979

[hansintheusa]

Hi Guys,
Recently my heater stopped blow warm air a couple of weeks ago. I have read a lot of threads here in the forum but nothing seems to fit my problem.
It does not blow ANY warm air at all, not even in the defrost mode. I had the climate control servo changed to a refurbished one, since my old one was dead ( didn't make any whirling noise at all when you turned the key on). The new one is making that whirling noise, but still NO warm air...
I have the wheel for adjusting the temperature and the 5 buttons on top of each otherand the on/off button for the A/C.
Just had a new thermostat installed, and it works fine.
Thanks
Hans
MB 280 CE 1979, 145.000 miles