SleeplessEyes, thanks for your expert explanation on this. Really appreciate this. Yeah, I would definitely prefer to be able to figure out what is the root cause and the culprit and fix that, rather than finding an easy way out and tweak other stuff. Well, bypass looks good, but I hope I don't have to do that

I'll send my car to a different workshop and see what they got to say about this. This time will focus on hose, plastic joints (where are they, I don't see any?) and whatever other connections.
All of you have been very helpful - thanks!!
Added on June 12, 2007, 9:11 amJimmy, I do notice that when it jams, the temperature rises, and then the fan kicks in, and subsequently the temperature goes down slightly.
However it looks like the fan doesn't turn long enough. It probably turns less than a minute. Then it shuts off. Then the temperature goes up again.
You see, if this keeps happening, eventually it goes beyond the 1/2 mark and 2/3 mark. I just feel that the fan is not turning long enough or probably not fast enough. The car just unable to cope with the "stress"

thats the good reason why i always use my aircond to unload the stress. Is the car setup of when the fan should turn. is not faulty.