Engine Over Heating Problem

[ksdst1]

So I have managed to check the fan by connecting the high speed and low speed leads to the positive battery leads. The fan works at both speeds. I also checked the fan relay by connecting from the battery negative lead to the yellow and yellow/white pins of the relay. The fan works at both speeds.

I read another post with an almost identical unresolved problem where there was talk about the ecu and ect. I don't much about this and am not sure if it's important.

I'm not sure what to check now.

[ksdst1]

Ah, the joys of car problems So the update;

Again, I jumped the fan and relay to make sure the fan and relay worked. I then recharged with two cans of 134a. The compressor stopped cycling quickly and I was getting cool (not cold) air but the fan never cam on. I am nervous to overheat. While running the a/c the temp gauge got to about 2 o'clock but the fan did not engage ever. I thought it was suppose to run as soon as the a/c compressor starts?? bad switch of some sort maybe??

So my bad luck. I'm not sure where to look. Hopefully not a new ecu b/c i think they are mucho expensive.
kevin

[ksdst1]

So today i decided to muck around with the ect thinking maybe when i replaced the rad a while back, i connected the ect male to female leads in their opposite order. Unplugged then replugged and no fan when turning on the a/c. Unplugged and replugged in the original positions and the fan engaged when i turned on the a/c....great! BUT, after letting the engine run to a higher temp and with the a/c off the low speed fan did not engage when the temp gauge started to move above 3 o'clock.....turned on the a/c quickly and again no fan..hhmm....so i banged the top of the fan housing and slowly the fan started making a slight rubbing noise...same situation w/o the a/c when the temp gauge moving higher.

Seems its slight resistance with the fan. I assume these fans don't take oil to loosen them up. If so i need to replace the fan. Great that at least i know the problem!!!

Tnx all for the input!

[FCPEURO]

After all that, I would not have thought the fan was the issue. You can get a used fan on ebay or your local pick and pull.

[henryhyva]

Hi.

All you may need to do get; Cooling fan relay ($30.00), (top of the radieidor), crey & black, super easy to change. I had problem to have AC always keep cooling (trafic red lights) and working when driving, until quit completely & over headed. I worried as, it may have head gasket gone, NO ITS this silly a little part...since that, cooling fan works as it should be and AC. Very a little known thing. Even my friend AC professional was not aware of...there you see, what these guys know...they will change every part in your car for & a lot of money, for almost nothing! I hope this will help & people read this very usual tip for the problem!

[kurts850]

Great thread. We only recently had our first 70 degree day and my coolant boiled. I had a shop install a new coolant temp sensor and thermostat and radiator hoses while there and asked for electrical troubleshooting on fan not coming on. They said the fan has no low speed, need new one at ~$500. I read-up here and after testing, it turns out my 5-year-old aftermarket fan only turns on with 12v applied to the high-speed female lead from the fan assy. Nothing happens when 12v is applied to other female lead instead. I suspect this mean my fan assy. is still good and I should fix it, not throw it away, but I need some suggestions on where to go from here. I have yet to cut into the wiring harnesses but I can only suspect that I have a broken wire on the low-speed circuit, yes? Are there other things to consider/test? I am a beginner at this kind of thing so any advice on theory as well as test strategies would be greatly helpful. Thanks all.

--Kurt

[kurts850]

Turns out to be a bad low-speed circuit on the fan. High still works fine. Not sure why the low circuit is bad. I suspect that the whole fan assy could be easily repaired by someone with better electrical skills.