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[jeff]

HI, 97 4.0l xj  lpgd kenlowe fan converted, As title said when i put ac on and electric cooling  fan kicks in it robs jeep of power also when temp rises enough and kenlowe fan comes on, the same result, jeep really struggles to tow caravan ,Tried it on petrol the same lack of power when either or both cooling fans are on, battery new last
year ,fitted kenlowe fan 18 months ago , Any ideas would be appreciated as cant get my head around this one the only thing i can think of ,is that the alternator is not pushing out enough power would that cause it ? any ideas!! 

[The Transporter]

Is it the running of the fan or the aircon compressor that is causing the increased load on your engine? The aircon can be felt cutting in and out on smaller engined vehicles but I would say that this should not be the case with a 4 litre jeep... Try pulling off the wire off the ac compressor, if this fixes the problem then your problen lies with the aircon compressor and is mechanical rather than electrical... what current is the cooling fan drawing?

[captain cavalier]

Carefull that second fan also cools your auto box so dont dissconnect it

[Dave69]

Carefull that second fan also cools your auto box so dont dissconnect it

the water flows through the whole rad so it's not sectioned into two parts with the aircon fan only cooling the right. The main cooling fan is sufficient to cool the whole radiator and the internal cooler for the gearbox is very efficient thus keeping the gearbox the same temperature as the engine coolant. I have ran my engine for over a year with only the main fan running with no issues, apart from the past couple of weeks where i have now reconnected it just as a precaution.

in what way does it lack power ? do you mean nothing happens when driving and you accelerate ? then this might not be electrical based and could be temperature related with some engine components.
 for electrical load if it is that, have the engine running hot in neutral (handbrake on) and then switch the electrical components on. this will give a load on the alternator causing the engine then to compensate by increasing the idle speed for a short period of time. or you could just measure the load across the battery or alternator but that takes two people.
 on some smaller engine vehicles it is possible to stall the engine when evey electrical item is switched on together

[jeff]

THanks for your replies, Dont think it is the aircon compressor as it happens when my kenlowe cooling fan comes on which i have set to come on a few degrees before the oem /ac cooling fan comes on, kenlowe fan is 13" heavy duty 25amp,when the kenlowe fan comes on at just over 100 on temp gauge the jeep is guttless just no real power wont pull in top at all, engine speed increases when idling and fan comes on ,Hope all that makes sense , jeff

[Dave69]

what do you use to set the temperature for the fan ? i assume it's adjustable. As for setting the right temp for the fan to come on, personally i would have gone for 90 degrees, this will mean that the fan is on for a shorter length of time plus when stuck in traffic the fan will start working force cooling the water sooner so reducing the heat soak from the engine and surrounding air especially in this weather. At 100 degrees the coolant temperature rise will be quicker when stuck in traffic after a good run and it only leaves 10 degrees to play with before you start to get worried about overheating. If the kenlowe shifts more air than the std fan then you should be ok.
 
With the engine altering for when the fan cuts in shows that it is responding to the initial ampage drain which is good but that shouldn't have an effect on the running of the engine. A basic check to see if it is the fan is to wire the fan via a manual switch so when you are driving as before but with the engine warm and not hot then turn on the fan and see what happens. if the jeep drives normally then that simply takes the fan out of the equation and the problem is elswhere.

[jeff]

dave69 The normal operating temp of jeep is 87 if i remember correctly, if i set my fan to come on at 90 wouldnt that mean that the fan would be on almost constantly?When at motorway speeds the temp is on one digit below 100, The oem fan comes on at just over 100 so i have set my kenlowe to come on just before it .What sort of output should the alternator be producing?

[jeff]

The kenlowe has a dial under bonnet to adjust it and a temp probe in top hose.

[Dave69]

as a general rule the alternator pumps out around 12.5volts at idle with no electrical load and when the engine is revved to say 1500/2000rpm the output should rise to around 14v. there are probably more specific information for each jeep but this gives agood idea for most car alternator output.s

[Mike Pavelin]

Why not disconnect the AC compressor and see what happens.

[jeff]

Dont think it is the ac compressor because it happens when the kenlowe fan is on and the ac oem fan /compressor is off.

[The Transporter]

In which case, I'd stick a clamp mter on to the positive wire to the fan and see what it is really drawing... There is no way that it should put such a strain on your alternator, surly!

[Mike Pavelin]

If the fan were to draw enough current to significantly slow down a 4.0 (which is highly unlikely) the fuse would blow, or if not fused the wiring would melt. I wouldn't have thought it draws more than 20 amps when running, which would only account for about 1/5 horsepower of the 180 odd available. Of course, if it was connected to something it shouldn't be it could be screwing up the electrical system I suppose.