mysterious defect in the heating system

A mysterious defect in the heating system in a Freelander (2.5 liters, 2000).
I apologize in advance for English, I translate using an automatic translator.

A mysterious defect in the heating system in a Freelander (2.5 liters, 2000). I apologize in advance for English, I translate using an automatic translator.
There is a strange heating defect. When the car is standing still, idling, the stove heats up, hot air is coming. But at speed, instead of hot air, room temperature air (about 10 degrees Celsius) comes from the grates. Naturally, such air cannot heat the car.
What is the problem? The car mechanic and I can't figure it out. The radiator of the stove is installed new. There is no antifreeze leak. Has anyone encountered anything like this?

If it is cold outside (and seeing your location I bet it is cold!) I would say you have a faulty stat.

lynall said:

If it is cold outside (and seeing your location I bet it is cold!) I would say you have a faulty stat.

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'Stat' will not cut it through the translator

He means you may need to change your thermostat ...

Dippypud said:

'Stat' will not cut it through the translator

He means you may need to change your thermostat ...

Click to expand...

The thermostat has just been changed

don.vertigo said:

The thermostat has just been changed

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I have had the same fault on a scania truck, I did not believe it was the matrix, but everything else was new, new matrix fixed it.
The old one had been flushed more than once, and whilst it was slightly better afterwards it soon faulted back to cold again.

Don't you just love how Google translate makes understanding an issue interesting.

I'd suggest that the heater matrix needs bleeding. There's a bleed valve in the heater supply hose, which needs to have the air removed, or water can't flow through the heater matrix.

Nodge68​

lynall​

If the radiator was clogged, it would not heat under any circumstances. But it still warms up.

If there was a bad thermostat, the motor would not heat up for a long time (cooling would go in a large circle), and the motor quickly heats up to normal and stably maintains a normal temperature. We checked the hoses of the car stove - they are very hot at the inlet and outlet.

don.vertigo said:

Nodge68​

lynall​

If the radiator was clogged, it would not heat under any circumstances. But it still warms up.

If there was a bad thermostat, the motor would not heat up for a long time (cooling would go in a large circle), and the motor quickly heats up to normal and stably maintains a normal temperature. We checked the hoses of the car stove - they are very hot at the inlet and outlet.

Click to expand...

No, you misunderstand

He means the heater matrix, the small radiator part of the heater

or, as Nodge said a bleed valve in the heater supply hose to let air out to allow water to flow

Dippypud said:

No, you misunderstand

He means the heater matrix, the small radiator part of the heater

or, as Nodge said a bleed valve in the heater supply hose to let air out to allow water to flow

Click to expand...

There's no need to bleed a Freelander heater matrix - they corode and let all the air (and coolant) out.

If the inlet and outlet are hot, then there is a partial blockage, either air or sludge.

If it goes cold while driving and hot while standing still, then, turn the fan to maximum, after a few minutes is it still hot?

don.vertigo said:

Nodge68​

lynall​

If the radiator was clogged, it would not heat under any circumstances. But it still warms up.

If there was a bad thermostat, the motor would not heat up for a long time (cooling would go in a large circle), and the motor quickly heats up to normal and stably maintains a normal temperature. We checked the hoses of the car stove - they are very hot at the inlet and outlet.

Click to expand...

This is not normal, see post 10