I am in Siberia, Russia with a 2004 Toyota Corolla. It blows heat but not much. The temperature gage shows normal operating temperatures. The defroster is a real problem. It only defrosts 1/3 of the windshield when temps are below -20C. At -30C with 4 passengers, there's only about 20% of the windshield defrosted. Heater does not do a good job of warming either. I almost had frostbite after a recent 200km drive in -35C temps.

Sounds like piston blow by, as the gap increases and diesels have such high compression. When the turbo kicks in, the pressure is restored.

https://www.google.com/search?q=Toyota+Corolla+2+Litre+diesel.+Why+loss+of+power+at+low+revs+when+warm

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Check the heater hoses at the engine firewall are they hot? If so then the air temperature control blend door is either jammed or the motor that operates it is defective or both.

Heat is blowing on passenger side, but cold air ... - RepairPal

repairpal.com > Questions > Dodge > Ram 1500 > 2002 Dodge Ram 1500

Dec 7, 2009 - When I turn on the heat, the passenger side is receiving warm/hot air but ... blow hot air on the drivers side and it would get cold right away. about a week ago... I have a 2008 Dodge Ram 2500 SLT. ... Regardless of the settings cold air blows from the left vent and on the floor on driver and passenger sides.

Temperature Blend/Recirculation Doors May Fail and ...

repairpal.com > Problems > Jeep > Grand Cherokee

2008 Jeep Grand Cherokee143,000Visitor. I get cold air on driver side and warm air on the passenger side. Upvote (29) ... right side air is always at the coldest. no heat on the right side and air temp will not change, left side works good. .... Models: · Honda Accord; ·; Toyota Camry; ·; Honda Civic; ·; Acura TL; ·; Toyota Corolla ...

Heating and AC Temperature and Air Delivery Mode Do

Check thermostat .

Check out related help links with solutions to troubleshoot the problem:---
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http://howtobyme.blogspot.in/2012/05/2004-toyota-tundra-oil-gauge-and-temp.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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These details will help.
Thanks.

if the car is at normal operating temperature and the car does not over heat and the air is cold you possible have a bad heater core.

This might be a problem with your tempeture sending unit for the gauge the other part might be your heater core.

Hello, and welcome to FixYa.

The normal operating temperature for a 2000 Corolla is 192 degrees F.
The cooling fans should be operating whenever the AC is requested, and the compressor energizes.

Thanks for choosing FixYa for assistance today.

check your in cabin air filter located behing the glove compartment. see your owner's manual for directions.
When this filter gets clogged air flow is restricted. You can blow the filter out with compressed air or replace. make sure you put in right side up.

check the coolant level, I had the same problem low coolant level.....no hot water to the the heater coil.