Engine Size: twin cam
I recently replaced a/c compressor,condensor,accumulator,orrifice tube,flushed remainder of system,charged.worked great for about 2 weeks.now the cooling fans wont come on.is there one sensor for both fans?is there a relay?i checked the fuses.what about wiring them so they are on when the key is on?you guys helped me before with my a/c questions,i know someone out there has the answers.it's a 200 focus zts,twin cam 4 cylinder.thanks in advance for the help.
Cylinder temperature sensor
Engine coolant temperature sensor
Engine cooling relay
High speed engine cooling relay.
All flow to both fans.
so,is there an easy way to have them on when the key is on?
Don't do that, the motors will wear out needlessly.
Next thing to check for fan problems after the fuse is to check the motors. Yes both can be bad at the same time because the car owner might not have noticed that only one was working for a while. Unplug them and jumper to a battery.
Also does the A/C still work while driving at highway speed? If not you have other problems than the fans not coming on.
Edited: Mon April 14, 2008 at 10:11 AM by mk378
You never stated why your fans were brought to your attention, engine overheating or poor AC performance can be two major reasons. Ironically with 85% of your fuel cost going up into wasted heat, fan and fan control seem to be major issues in the automotive industry, have them and use them as infrequently as possible when in the overall picture, the energy these fans use is only a drop in the bucket. For cooling, the fans don't even come on until the cooling system is ready to pop it's cork and that is if they are operating correctly..
Fans use to come on the instant you switched on the AC, now they wait until the high side is just about ready to pop it's cork as well. Make sense? Probably if you work in marketing where you pick on the least significant parameter to claim better fuel economy. The law of physics is against FWD vehicle electric fans, you require the most cooling when the alternator is least capable of providing that extra energy.
Best bet is to only drive at highway speeds, but tell that to the guys that are planting a traffic light at every corner that stays red even without any cross traffic or to your highway department for letting 50 years go by without upgrading the interstates, but still managed to increase the gas tax from a nickel a gallon to over 50 cents.
One vast aftermarket improvement is a thermostatic switch mounted to your radiator tank to switch on the fans when the coolant temperature exceeds 160*F that corrects that constant thermal cycling between 195 and 230*F with the cheap ass ECT method of controlling the fans. This really stresses out aluminum heads on cast iron blocks, but you will also have to upgrade your alternator to have sufficient electrical energy to run them longer. Would be nice if they made these fans so they can be lubricated, but hey, they are lubricated for life!!! The life of a mosquito?
I wouldn't even attempt any fan troubleshooting without the aid of a circuit diagram, get an alldata.com subscription not only to see the circuit but for the parts location, that will save you hours as none of the parts are even identified and all these modules pretty much look all alike, especially relays.
Have no idea what they were thinking with these fans or fan control circuits, but maybe they weren't even thinking.
Edited: Mon April 14, 2008 at 10:51 AM by NickD
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