2003 Ford Taurus: A/C Fan not Coming On Time?

AC blower/heater fan is running and starting up.But its not coming up on required time.

You will notice that it comes up when pressure gets too high like 320psi or 350psi or even more then that.

This is most likely a faulty ac dual pressure switch. If it fails, the fan wont come on at proper time and the compressor wont kick off when pressure gets too high, which 350psi is.

As per wiring diagrams if you see:-----
The  fan operation is controlled from the pcm, when the pcm turns the ac clutch relay on it should also turn on the fan relay but isnt. The fan kicks on when high side pressure reaches more then  300psi , and in this condition  compressor  stays engaged as well as pressure then drops and this is not good for compressor.

The pcm gets 2 signals for fan control - one from the ect sensor and one from the dual pressure switch:---
See the wiring diagram shown below for your help:-----




So if the dual pressure switch is acting up the pcm dose not recieve a signal to trun fans on for normal operation.

If dual pressure switch is not working properly, two things happen - head pressure goes up too high as the pressure switch should cut the compressor off when pressure gets too high and fan doesnt cut on when it should to help keep the pressure lower.

And this explains that the signal to the compressor and the fans is not correct due to the dual pressure switch not functioning correctly which is causing the pressure to rise too high and your fan not to turn on until pressure is at 350.

This details will help.

Thanks.

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What is AC pressure and Temperature sensor ?

If you need dis-assembly or replacement instructions for any other auto/car part, or you want to ask question related to your car/truck jeep problem then please leave the comment with your details, so I can provide you the required instructions and solutions.




A/C Temperature Sensor or Pressure Sensor Operation:An electrical or mechanical sensing device that sends information relative to some physical property such as temperature or pressure to a gauge or light. Also known as sensor unit.


This is how this Sensor looks:---

You can easily buy this part from Autozone service center.

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This details will help.

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Also if you have better understanding of other car AC cooling system parts,then it will help more to troubleshoot the problem.

Check the list below or more help.

Its always advisable to know the AC components working and testing procedure,before replacing any part.

For more details regarding cars AC components.Check out the list of links below:---

How to Perform Car AC Leak detection Test?

http://repairhelpcenter.blogspot.com/2011/11/how-to-perform-car-ac-leak-detection.html

How to Perform AC Pressure Test?

http://repairhelpcenter.blogspot.com/2011/11/how-to-perform-ac-pressure-test.html

How to test Cars AC System?

http://repairhelpcenter.blogspot.com/2011/11/how-to-test-cars-ac-system.html

How to inspect Vehicles A/C Compressor and Clutch?

http://repairhelpcenter.blogspot.com/2011/11/how-to-inspect-vehicles-ac-compressor.html

How to Troubleshoot Vehicles AC Cooling Problem?

http://repairhelpcenter.blogspot.com/2011/11/how-to-troubleshoot-vehicles-ac-cooling.html

How to Replace Vehicles A/C Compressor and Clutch Components?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-vehicles-ac-compressor.html

How to inspect Vehicles A/C Condenser?

http://repairhelpcenter.blogspot.com/2011/11/how-to-inspect-vehicles-ac-condenser.html

How to Service Car AC Condenser?

http://repairhelpcenter.blogspot.com/2011/11/how-to-service-car-ac-condenser.html

How to Replace Auto AC Condenser?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-auto-ac-condenser.html

How to Replace Vehicles A/C Evaporator Core?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-vehicles-ac-evaporator.html

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For car AC related and Heater related solutions. You can refer the options mentioned below:---

Car AC Blows Warm Air ?

http://technoanswers.blogspot.com/2011/10/car-ac-blows-warm-air.html

How to test AUTO AC pressure?

http://howtobyme.blogspot.com/2011/10/how-to-test-auto-ac-pressure.html

AUTO Air Conditioning Troubleshooting?

http://technoanswers.blogspot.com/2011/10/auto-air-conditioning-troubleshooting.html

AUTO A/C COOLING PROBLEM?

http://technoanswers.blogspot.com/2011/10/auto-ac-cooling-problem.html

Fixing refrigerant leak?

http://howtobyme.blogspot.com/2011/10/how-to-fix-refrigerant-leak.html

How to locate Car AC Refrigerant leak?

http://technoanswers.blogspot.com/2011/10/how-to-locate-car-ac-refrigerant-leak.html

CAR AC INTERMITTENT COOLING?

http://technoanswers.blogspot.com/2011/10/car-ac-intermittent-cooling.html

What causes INTERMITTENT COOLING on Car AC system?

http://technoanswers.blogspot.com/2011/10/what-causes-intermittent-cooling-on-car.html

Car AC making Noise?

http://technoanswers.blogspot.com/2011/10/car-ac-making-noise.html

BAD ODOR ON CAR AIR CONDITIONER?

http://technoanswers.blogspot.com/2011/10/bad-odor-on-car-air-conditioner.html

How to Recharge Car's Air Conditioner

http://repairhelpcenter.blogspot.com/2011/10/how-to-recharge-cars-air-conditioner.html

For details regarding:--

How does Vehicles Engine cooling system works?

http://repairhelpcenter.blogspot.com/2011/11/how-does-vehicles-engine-cooling-system.html

Engine cooling components working?

http://repairhelpcenter.blogspot.com/2011/11/engine-cooling-components-working.html

How to flush cars radiator?

http://repairhelpcenter.blogspot.com/2011/11/how-to-flush-cars-radiator.html