AC fault My AC once turned on does not either blow cold or hot air! What should i do to rectify this problem?

check for a fault in the climate control module that is affected by a power surge/ depletion from the brake circuit. It would appear that the ac compressor is being switched off by the fault and switches on again when you recycle the switch( could be a relay to the ac compressor.)

bmw 5 series on 2005 2.5 diesel when i put the heats on hot air it blows cold air.

Check to see if the radiator fan is coming on & the AC fan comes on when the AC is turned on. AC Freon may be low too.

Sounds like a blend door problem under the dash.

As per your problem mentioned.There are few solved help links to troubleshoot these problems.Go through the list and Click the link below:----
Air conditioner blows air but not cold air http://repairhelpcenter.blogspot.in/2012/07/air-conditioner-blows-air-but-not-cold.html

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Car overheats and Air blows hot at idle? http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

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Heat blows cold on drivers side and hot on passenger side? http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html---------- Hot air on the driver's side vents only? http://repairhelpcenter.blogspot.com/2012/01/hot-air-on-drivers-side-vents-only.html

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2005 Chrysler PT Cruiser: A/C Blows Warm? http://whoisbyme.blogspot.in/2012/06/2005-chrysler-pt-cruiser-ac-blows-warm.html

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1992 Toyota Camry: A/C Control light Flashing and A/C not Blowing Cold? http://technoanswers.blogspot.in/2012/04/1992-toyota-camry-ac-control-light.html

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No heat, blower blows only cold? http://technoanswers.blogspot.in/2012/02/no-heatblower-blows-only-cold.html

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These will help.
Thanks.

you say it will blow cold and hot air for only a few minutes. You don't say but I assume you mean will blow cold a few min. when turned on AC max , blow hot only a few min. when turned to heater hot. Assuming thats the situation and you say AC charged and shows good on the low side -you should charge the AC to a full charge on the low side will cause problems with the AC air compressor kicking on and off. I suggest while the engine is running and turned to AC cold max watch the AC air compressor clutch to see if it does indeed kick on and off if so charge completely. As far as the heater make certain you coolant is all the way to the top and the best way to do this is when engine is completely cold remove radiator cap and fill completely and completely close cap then fill overflow container just to the cold level. That should fix your problem.

Your heater core may be clogged

sounds like u guessed right blender door is getting stuck motor is weak or mount is cracked

if it is the same thing that is wrong with my frontier. check to see if the compressor is turning on when you use the ac. if not you might have a bad connection that is intermittantly preventing the compressor from getting the signal to turn on. get a service manual and a voltmeter and you can fix.

Turn your AC off. Turn the car off Crank the car turn ac on drivers side to 60 passenger side to 90 press auto wait 1 minute turn AC off (very important) turn car off turn car back on switch driver's side 90 passenger 60 press auto wait one minute turn AC off( very important) turn car off turn car on AC 70 both sides press auto your ac should be blowing cold If not, you have an expensive problem