Chevrolet Repair: Trailblazer fan clutch, fan clutch, driving condition

Question
Hi Wayne,
I drive a 2004 Trailblazer L6 4.2L 4x4 with 74 000 miles. I noticed during the last summer that the AC needed about 5 min to start cooling when start the vehicle with +90 degrees outside (note I live in South Florida. Now with 70 degrees outside, when I am stopped in heavy traffic (stop and go) the engine temperature rises close to the red line (260) it gets worse with the AC on. Under normal driving condition (speed above 40mph) and at highway speed the temperature remains normal, in the left half of the thermometer. I did my researches and could be the the fan clutch, if so can I use an electronic one or has to be thermal (the autopart sells both). I've also read the electronic need the computer to be reprogrammed.
Please advise and thank you in advance.
Pavel

Answer
Hey Pavel,

  The fan clutch is not a terribly common repair but it does happen.  You may find it quite a bit easier to replace the clutch itself as opposed to installing an aftermarket electric one and probably less expensive.  I can assure you the mechanical viscous clutch is much more reliable than the electronic ones.  The electric one will enhance fuel economy and engine performance but not by a huge margin.
  One thing to check before you do though is to make sure there is no obstruction in front of your condenser.  The condenser is mounted in front of the rad and when you look at it note the aluminum fins and make sure they are not all bent over or filled with leaves and debris.  This lowers the condensers ability to radiate the high pressure refrigerants heat and the ac system actually accentuates the overheating problem.  PUll the top rad cover off and look down in between the rad and condenser as well.  I have seen everything from plastic bags to animal homes in there causing overheating problems.  Its -15c where I am right now but our summers get plenty hot for lots of overheating and AC repairs.  The corrosion levels around here due to electrolyis and road salt give us plenty of AC work to do.
  When inspecting the clutch fan grab it (with the motor off!) and try to move it side to side.  There should be no lateral movement of the blades and look for a stain of fluid illuminating around the clutch itself  .



Wayne