Cooling fans refuse to work right

[aaron_t_graham@xxxx]

I've read all the posts I can find about fixing cooling system 
problems, and I've replaced everything of any significance in the 
cooling system in the last 6 months:

About 4 months ago, DMC Houston diagnosed and repaired a problem with 
the wires running to the cooling fans. That was the beginning of my 
cooling system problems. About 2 months ago, the water pump started 
making a lot of noise. I also had that replaced.

About two weeks ago I noticed that when I sat idled for a long time, 
the temperature got dangerously high, and the cooling fans would not 
come on. Thinking I had the infamous air bubbles in the water pump, 
I bled the air from the water pump and promptly installed the self-
bleeder overheat protector kit. This didn't solve the problem.

I know coolant is circulating through the system, because if I take a 
2 hour drive on the interstate, the engine stays cool. However, if I 
sit in stopped traffic for 5 minutes (poorly designed traffic systems 
make Urbana-Champaign a perpetual traffic jam), the temperature 
quickly rises above the 220 mark.

The cooling fans come on when the A/C compressor is on, and when I 
short the fan switch wires together, the fans are on constantly. 
Thinking the fan switch would be the only thing left to replace, I 
installed a new one. This, also, did not solve the problem.

I have now hit a brick wall. I figured I could bleed the entire 
system, but I'm not convinced that will do anything. I know coolant 
is circulating past the fan switch. The fan switch is on the 
*bottom* of the radiator pipe, and the pipe gets extremely hot when 
the engine is running. The pipe and adjacent hose, like in most D's, 
I assume, are inclined slightly so any air bubbles in that pipe would 
propagate up to the water pump.

Or I could order *another* cooling fan switch...

If anyone has a clue what I could try next, please let me know.

Aaron
#1506