Warm air from dash vents but cool air from defrost

As per your problem mentioned. There are few solved help links to troubleshoot these problems. Go through the list and Click the link below:----

2000 Toyota Avalon: No heat on Passenger Side?

http://whatisbyme.blogspot.in/2012/05/2000-toyota-avalon-no-heat-on-passenger.html

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No heat on Oldsmobile Silhouette?

http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.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

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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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Temperature gauge does not move and no heat when heater is ON?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.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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Ford F150 Ac only blows through defrost vents?

http://technoanswers.blogspot.com/2012/01/forf-f150-ac-only-blows-through-defrost.html

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Dodge A/C come out of defrost vents only?

http://technoanswers.blogspot.com/2012/01/dodge-ac-come-out-of-defrost-vents-only.html

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Ac vacuum line on dodge cummins?

http://technoanswers.blogspot.com/2012/01/ac-vacuum-line-on-dodge-cummins.html

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Ford ranger AC blows cold through defrost vents instead on cabin vents?

http://technoanswers.blogspot.com/2012/01/ford-ranger-ac-blows-cold-through.html

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2005 Chrysler PT Cruiser: A/C Blows Warm?

http://whoisbyme.blogspot.in/2012/06/2005-chrysler-p8t-cruiser-ac-blows-warm.html

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2009 Mercury Grand Marquis: A/C blows Cold From Defrost Vent Only?

http://whoisbyme.blogspot.in/2012/06/2009-mercury-grand-marquis-ac-blows.html

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AC not blowing through Vents on 2007 Chevy Trailblazer?

http://schematicsdiagram.blogspot.in/2012/04/ac-not-blowing-through-vents-on-2007.html

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Passenger side temperature is warm air out of dash vents?

http://schematicsdiagram.blogspot.in/2012/04/passenger-side-temperature-is-warm-air.html

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These will help.

Thanks.

CHECK FOR LOW COOLANT,NOT ENOUGH COOLANT IN THE SYSTEM.IF COOLANT LEVEL OKAY.THERMOSTAT NEED CHANGING STUCK OPEN.IF THERMOSTAT BEEN REPLACED.CHECK BOTH BOTH RADIATOR HOSES AND HEATER CORES HOSES THEY ALL SHOULD BE VERY HOT.IF ALL HOSES HOT AND BOTH HEATER CORES HOSES GOING INTO FIREWALL IS HOT.HEATER DOOR NOT OPEN ALL THE WAY OR STUCK.IF ONE OF THE HEATER HOSES GOING INTO FIREWALL HOT AND OTHER HEATER HOSE COMING OUT OF FIREWALL NOT HOT.MORE LIKELY HEATER CORE PLUGGED NEED TO FLUSH OUT COOLING SYSTEM.FLUSH OUT COOLING SYSTEM IF NOT BEEN DONE IN A LONG WHILE.

Thermostat.? if you haven't? Do it first then try it. While the car is running for a while touch the heater hoses that lead to the firewall. if one is cold and one is hot? You have a blocked Heater core. Follow the hoses back to the engine. Unconnect them both. By using a garden hose flush out the heater core do one side and then reverse by doing the other hose Lots of junk will come out so be care ful. Mistake people make is "Flushing the system" That doesn't mean your flushing the heater core.
Seeing that you have done everything else it could be the thermostat which you didn't list or the heater core being clogged. When you finished installing the thermostat and flushing the heater core out. Replenish the coolant system . If you have a bleeder on the thermostat housing? use it . loosen it and top off the fluid until you see fluid comeout of the bleeder. The system being air bound would cause no heat..

your heater core bad.

Check these three possibilities: One, car has a bad thermostat. Two: Car has a bad heater control valve and three: Car has a vac leak under the dash that controls the heater Flap Valve. If this flapper isn't closed completely, cool outside air mixes with the warm inside (recirculating) air and cause a lukewarm air mixture at the vents.

Feel of the heater hoses going to the heater core,if they are not getting hot,then remove the heater hoses and flush the heater core out with a water hose.Also be sure to bleed all the air out of the cooling system.

you may need to flush directly through heater core hoses...disconnect hoses and flush through both ways until runs clear...you may have to remove heater core to accomplish this...if clogged bad replacement may be necessary

Check the coolant level.Feel the heater hoses going to the heater core to see if they are warm,or hot.If one of them is warm,or hot,and the other is not,remove the heater hoses,and flush the heater core out with a water hose.Bleed the coolant system,and you might want to install a new thermostat while you are at it.

The heater core is probably clogged. The best method i have found is to remove the heater hoses, and blast compressed air into one side or the other in short bursts. This will tend to launch a clump of sludge out of the other side, and is very messy. Once the heater core is unclogged and reconnected, it is a good idea to chemically flush the entire cooling system, then flush with clean water and refill with universal coolant.

feel the two hoses going into and out of the heater core. they both should be hot. if one is cold the heater core is likely plugged. you can try flushing it out to see if you can restore flow to the heater core. if they are both hot the thermostat may be sticking open tho you should have a limited amount of heat. also confirm that the vents are operating as they should be.

robert