Heater fan works in warm weather not in cold - DeVille Cadillac Cars & Trucks

What is happening here is that the faster the heater blows air through the fan, the more it cools the liquid in the heater core, and so heat output is reduced. The root of the problem is either the engine is not warming up enough, or the heater core, and/or heater core lines, are plugged up, not allowing the water to circulate properly in the heater core. Here is what I would try.

1. Top off the radiator and overflow.
2. Is the engine warming up properly? Is your temperature gauge showing normal temperatures? If it is not, then replace the thermostat.
3. If steps 1 and 2 do not solve the problem, get the vehicle in a shop, locate the heater core lines, take them apart and flush out the heater core. Look for blockages in the fittings. Do a flow test on the core. It may be clogged and need to be replaced.

Bad news ,nothiong worse than a cold car so iam assuming this is a 16v job and the thermostat is behind the timing belt which is a summers day type job ,so as a temporary fix put a sheet of cardboard in front of the rad till the weather warms up this will make the engine run hotter and the cars internel heater radiator will be all the cooling it needs in the cold weather

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.

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Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.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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No heat on car? http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.html

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Heater blows intermittently and temp gauge goes erratic? http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html------------Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html
---------Car heater blowing warm, but not hot air? http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html-------- Heater/AC blower motor not working?

http://technoanswers.blogspot.in/2012/02/heaterac-blower-motor-not-working-on.html

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A/C, heater, defroster fan, not working? http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html Heater problem? http://technoanswers.blogspot.in/2012/02/heater-problem-on-isuzu-trooper.html---------

This will help.Thanks.

sounds like the fan bearing is is going out and it is wore you might have to replace the fan it self warm weather it goes cold it gets stiff no lube

could be the thermostat if it was just stating to go bad,could also be a vacume problem not letting the door for the ac/heat close all the way for a few min.and if its really cold out like below 35,then its going to take longer to warm up,my jeep takes like around 20 min at idle to warm up.yours could be a case of over cooling in cold weather too ie(electric fans on before it warms up)that would be the thermostatic sensor.

For this types of problem,i suggest you to check this help links:----Car heater blowing warm, but not hot air?http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html
---------A/C, heater, defroster fan, not working?http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html
--------Heater problem?http://technoanswers.blogspot.in/2012/02/heater-problem-on-isuzu-trooper.html
---------Engine Overheats and heater blowing cold?http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html
-----------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----------------This will help.Thanks.

did you install correct temperature thermostat? also is the temp guage in the car working and what does it read, if it reads a normal reading then the fan may be working improperly.

Put a heater inside the motor compartment with a fan so you can warm the engine up. throw a piece of plastic over it so the battery will warm up too, after about an hour it should get warm enough to start then buy a in line heater for the engine at any parts store and leave it plugged in at night so you can start it in cold weather. hope this helps.

sounds like the thermostat stickng as when engine gets cold the choke will start workin again, causing the over reving or your electric fan is on all the time "over cooling" the engine

impeller is made of plastic on teh water pump and its slipping and spinning on the shaft renew before weather warms up as engine will overheat