nhangel

I have a 1990 Toyota Camery that the heat works crazy. When the car is running it works just ok but not real hot. then if I stop at a red light for an example the heat runs cold. this happens no matter how warm or cold it is outside. I know this sounds strange. Can some one please give me some idea's Thank you.

JOET/CAMRY

Hello nhangel,
your car could have a thermostat that is stuck in the open position. another possibility is the valve that allows the coolant to flow through the heater core might not be opening all the way when you adjust the hot/cold temperature lever in your car. does your radiator and coolant overflow container have the proper amount of coolant in them? these are things that you might want to look into. anyone else have any ideas?
Good luck.

JOET/CAMRY

nhangel

Thank you I will try those things and let you know.

RIP

Something else to consider. Not sure this is the case but on many cars the ventilation system doors in the heater unit are vacuum actuated. When you're at idle at a light, vacuum produced by the engine increases. When you accelerate, vacuum decreases. When you take your foot off the gas to slow down, vacuum increases. Does your heat and cold tend to change with your accelerator pedal movement or close to it? Could be a vacuum leak or a bad regulator. Let us know.

Brian R.

Another possibility is that you have some air trapped in your heater core and it moves when your water pump is running fast and settles back in the core when it isn't.

You could try parking the car with the radiator uphill from the engine/heater core and start the car cold and let it warm up with the radiator cap off. Let it run at 1500 rpm for a few min after the thermostat has opened and the radiator is hot and see if you get a drop in the coolant level in the radiator. Add some antifreeze to make up for any loss and cap it off.

Your heater core may be plugged up also. You can try reverse flushing it and see if that helps.

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JOET/CAMRY

The 1990 camry doesn't have vacuum actuated ventilation system doors for the heat or air conditioning unit. I know because I own a 1989 camry. the second generation camrys were made from 1987 - 1991. I think the newer camrys have this type of setup. I'm not sure.

Regards,
JOET/CAMRY

RIP

JOET - thanks for the feedback. Cheers!

Mike Gerber

You may also have a leak somewhere in the cooling system and the car is low on coolant. When you rev the engine, the water pump is pumping faster and a bit more coolant circulates throughout the cooling system; this includes the heater core. This is when you will get the most heat in this case. When you are stopped and the car is at idle, the water pump is turning slower and may not be pumping coolant throughout the cooling system. If there is no coolant flowing through the heater core, you will get little or no heat.

When the car is cold, check the coolant level in the radiator and the overflow tank. If it is low, add the necessary amount of a 50/50 mix of antifreeze and water and bleed all the air out of the system as Brian described. Then see if the heater is back to normal. If it is, then check the system for leaks or have it checked and repaired by a professional.

Mike