Mercedes: Overheating, number search results, radiator hose

Question
I have a 1991 300TE and as soon as the weather turned hot this year my car continues overheats and boils out all the antifreeze when using the a/c.  The 2 electric fans do come on but only with the temperature having risen real high.  I would prefer to have the electric fans kick on when the a/c turns on.  I have removed the thermostat and installed a new radiator cap.  One interesting thing is that as the temp rises, I try to cool it down with a garden hose directly on the front of the radiator through the electric fan openings but I noticed the temperature gauge does not come down.  Could this be a water pump problem.  I have 240,000 miles on this car.  Could it be a radiator problem?

Answer
Answer:

Stop driving it or the engine will be wrecked.

This sounds like a failed water pump, common on your model.

The thermostat MUST be installed for correct coolant flow.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1991 Mercedes Benz 300TE Wagon
Part: Water Pump
 Note:  
Models prior to indicated engine cut-off require (1) 104 203 08 02 drain line. Water pump does not include 110 200 05 15 thermostat or 103 203 07 74 thermostat housing cover. Earlier versions of of 103.983 engines require (1) 103 200 14 52 return line and (1) 124 501 33 82 lower radiator hose.     
 Engine: 12-268716-
G3000-28256 Water Pump    IN STOCK
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You may also have issues with these two switches.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1991 Mercedes Benz 300TE Wagon
Part: A/C Temp. Switch
 Note:  @ receiver drier
Located on receiver drier for auxiliary cooling fan. Identified by 2 spade terminals on short pigtail with red base.     
R1055-29376 A/C Temp. Switch   IN STOCK   
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PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1991 Mercedes Benz 300TE Wagon
Part: A/C Pressure Switch
 Note:  
2 bar low pressure and 30 bar high pressure binary switch. This switch is designed to be compatible with R-12 and R134a refrigerants. Located on receiver-drier with 2 spade terminals. Used for compressor cut-out.     
R1054-178181 A/C Pressure Switch   IN STOCK  
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