Mercedes Benz repair: mercedes 280 se climate control, mercedes benz 280se, mercedes 280 se

Question
I have a mercedes 280 se 1979 and my climate control is acting up. When I warm up the car in the winter the heater will kick in ...but after driving and shuting off the car and starting it up again the climate control will always stay cold.  

Answer
Best guess:
#1. Auxiliary Water Pump failing after it warms up.
#2. Heater core plugged with sludge.

Climate Control:
http://www.mercedesshop.com/shopforum/showthread.php?t=142408


PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1979 Mercedes Benz 280SE
Part: Auxiliary Water Pump
 Note:  
This unit has 12" lead wire. Bosch 0.130.002.070     
G3050-12429 Auxiliary Water Pump Bosch IN STOCK $173.86  

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc...