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The coolant was changed today but still the heater blows cold air out, Warm air only blows in when fan on low speed, Radiator okay no leaks. The two pipes which go into the car, looking from the front, the left one is cold the right is hot. The air distribution is not balanced as the passenger side starts to blow warm air whilst the drivers side blows cold, I compensate this by using Dual Zone and reduce the passenger side by at least 4 degrees. The above problems are only obvious when the outside temperature is below 5 degrees.

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The coolant was changed today but still the heater blows cold air out, Warm air only blows in when fan on low speed, Radiator okay no leaks. The two pipes which go into the car, looking from the front, the left one is cold the right is hot. The air distribution is not balanced as the passenger side starts to blow warm air whilst the drivers side blows cold, I compensate this by using Dual Zone and reduce the passenger side by at least 4 degrees. The above problems are only obvious when the outside temperature is below 5 degrees.

hi mate

the circuit is blocked by an air pockets, so you have to escape the air more + add more coolant.

Cheers/Igor

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Excuse my ignorance but how do you get rid of the airlock

ok you ve stated the coolant has just been changed - it is presumed the air was not escacped in full giving an air pockets unfilled by coolant - in other words no solid coolant flow available to transfer an engine heat towards.

Cheers/Igor

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Excuse my ignorance but how do you get rid of the airlock

Get the engine running and start squeezing the main pipes that come in and out of the radiator. That should get the air moving.

Let things cool off (shouldn't take long at the minute!) and then top up the coolant.

You might need to repeat this a couple of times.

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Hi folks,

I have a similar problem with my 2004 T3-S Avensis following a water pump and coolant change. I suspected it was because some air was trapped in the system but didn't know how to remove it. I will try theoilburner's suggestion and let you all know how I get on. Thanks

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Hi,

When filling the cooling system with new cooling fluid, you normally proceed as follows.

- Leave the radiator- and expansion vessel caps off

- Set the heater regulator to maximum temperature

- Fill the radiator

- Replace the radiator cap

- Fill the expansion tank

- Start the engine and let it warm up

- Keep an eye on the level in the expansion tank and keep filling to maximum

- Rev the engine a bit, to make the water pump push the remaining air out of the heater.

When the level in the expansion tank no longer drops, feel the temperature of the ingoing and outgoing hoses to the interior heater.

They should both get warm.

If not, close the expansion tank and with the heater still at maximum hot, go for a good drive.

You should now be gradually cooked. :)

- Check the fluid level in the expansion tank again and fill as required.

- Checks for leaks.

- Done.

And as Theoilburner wrote, squeezing the warmest of both heater hoses helps to get the circulation going and to push the air out of the heater and towards the expansion tank.

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Hi,

When filling the cooling system with new cooling fluid, you normally proceed as follows.

- Leave the radiator- and expansion vessel caps off

- Set the heater regulator to maximum temperature

- Fill the radiator

- Replace the radiator cap

- Fill the expansion tank

- Start the engine and let it warm up

- Keep an eye on the level in the expansion tank and keep filling to maximum

- Rev the engine a bit, to make the water pump push the remaining air out of the heater.

When the level in the expansion tank no longer drops, feel the temperature of the ingoing and outgoing hoses to the interior heater.

They should both get warm.

If not, close the expansion tank and with the heater still at maximum hot, go for a good drive.

You should now be gradually cooked. :)

- Check the fluid level in the expansion tank again and fill as required.

- Checks for leaks.

- Done.

And as Theoilburner wrote, squeezing the warmest of both heater hoses helps to get the circulation going and to push the air out of the heater and towards the expansion tank.

:thumbsup:

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Hi all,

Just to update you on this; I spent about a half an hour on this today and I think I might have cured the cool air issue. I did as you suggested (Theoliburner and Thermal) and ended up putting almost another litre of coolant into the system (making it about 4 litres of coolant in total). I was amazed at how much coolant it took! I also squeesed the upper (hot, return) heater hose and saw plenty of air bubbles in the expansion tank. I think I have finally removed all of the air from the system. I then ran the car for about another 30 mins and had consistent hot air from the cabin heater.

So thanks again folks for the advice :thumbsup:

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Hi,

Thanks for the feedback, and glad to see you fixed it before the winter starts.

Above, I explained the procedure for filling and bleeding the cooling system.

Now that I'm at it, I might as well add draining the cooling system.

With respect, but you seem to be surprised about the cooling system's content.

It's in the Owners guide, and you should have checked how many liters came out when draining it, to check that none has disappeared (which could be an indication that the Head gasket is going.....)

Buy the pink Toyota stuff, it's pre-mixed, not overly expensive and contains an anti corrosion additive.

Draining:

- Look in the owners guide how much coolant to buy

- start the engine

- set the interior heater to max hot (important, to also drain the heater radiator)

- switch off the ignition and put the key in your pocket (..)

- have a large enough bucket, pan or whatever, ready to collect the old fluid

- open the expansion tank cap

- open the radiator cap

- open the drain tap on the bottom of the radiator.

- allow all fluid to drain and check how much came out.

- close the radiator drain tap

- go to "filling and bleeding the cooling system" procedure and fill the new fluid.

Start with filling the radiator and fill slowly, to enter as little air into the system as possible.

Just for the record, while you have an empty cooling system, it may be an excellent opportunity to replace the thermostat, as "preventive maintenance".

Thermostats only cost a couple of €/£ and replacing it now is one thing less to worry about for a couple of years.

(Replacing a failing thermostat requires draining and refilling the cooling system.)

One more thing: bring the old fluid back to where you bought the new.

It's "not so nice" stuff. :huh:

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I have a similar problem to this...got some heat..but not much and better on the passenger side than driver. Which hoses should I be checking for air locks? There is a huge one coming out of the top of the radiator passenger side, then behind the air filter box there are 2 alongside each other leading to the dashboard, all these appear to be working correctly and Coolant level high. Could the air be trapped elsewhere if so can someone send me an annotated engine diagram. No fun in this freezing weather

Many thanks in advance

Regards

aabrass53

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