HEATER PROBLEMS

[ANDKAT]

Hi all,

Been a while since I last posted on here so I hope everyone is well.

Been having heater issues and i'm a little confused.

When I run the vans engine (1.9 watercooled) and get it up to temperature then put on the heater blower it only blows cold air, no matter what the setting, until I start to drive the van. When it's moving it will blow warm. Again until you stop moving then it blows cold again.

All the cables etc appear to be attached so does anyone have any hints as to what the issue could be.

Thanks for your time

[California Dreamin]

When I run the vans engine (1.9 watercooled) and get it up to temperature then put on the heater blower it only blows cold air, no matter what the setting, until I start to drive the van. When it's moving it will blow warm. Again until you stop moving then it blows cold again

The heater system in a car/van relies on the water pump and it's impellor (fan) to circulate the hot coolant around the engine, to and from the radiator AND around the heater matrix inside the car.
Without the engine running the heater matrix (small radiator inside the car) will not recieve the hot coolant it needs in order to blow warm air into the cabin.
The way it works is to blow normal ambient air through the fins of the matrix which imparts heat to the air as it travels into the cab.

It is possible I've not understood your question and you are saying 'even with' the engine running but this was not my interpritation of your original post.
If this is the case you may have an air lock in the system or the heater valve isn't working correctly (variable coolant control valve) not allowing the hot coolant to the matrix. There is also the possibility of a broken heater control cable or flap.

Martin

[ANDKAT]

Hi Thanks for the reply, I should have made it a bit clearer, the engine is running all the time, when the vehicle is moving the heater blows warm and when the vehicle is stationary the heater blows cold.

The cables all look ok and the flaps sound as if they are okay, if its an air lock whats the best way to try and clear it?

I was wondering about the heater valve, but surely this would not make a difference whether the van is moving or not?

[California Dreamin]

...so are the three speeds working on the blower motor as this sounds like natural air movement (when the van is in motion).

Martin

[ANDKAT]

Yes the blower works fine on all speeds.

When the van is stationary with the engine running and up to working temperature, if you turn the heater blower on it only blows cold air not warm, no matter what settings the levers are on.

As soon as you start driving it blows warm air.

This is without altering anything.

[California Dreamin]

Gotta be some kind of air lock in the system...sounds like the cooling system needs bleeding.

Not wishing to ring alarm bells.....but this is also a common indicator of head gasket failure.
First things first, bleed the cooling system from the radiator, it might help to have the front raised slightly aid bleeding the air out to the front.
Check fan belt tighness.

Martin

[ghost123uk]

A bit odd this but I have to agree with Martin, the only thing I too can think of is an airlock that is sitting in the heater matrix until the revs get up (during driving) forcing the air lock out of the matrix. A test would be to sit stationary with the blower on but hold the revs at a fast tickover (simulating driving at say 40 MPH in 4th) for a few minutes. If this then produces warm air we are likely on the right track. If not, err, well I don't know...

[ANDKAT]

Hi Guys
Thamks for your replies.

I have tried revving the engine this morning and it does blow warm, so I'm guessing this is an airlock.

Is it possible to bleed the system on your own?

I've had a go by revving the engine quite high and then running around and retightening the bleed bolt but i'm concerned air will get back in.

Would it be better to park on a hill if i'm doing it myself?

Sorry for such sill questions.

[ghost123uk]

I have tried revving the engine this morning and it does blow warm, so I'm guessing this is an airlock. Agreed- E D I T = or possibly a weak flow of coolant around the system caused by a blockage, a duff water pump (unlikely) or even a slipping fan belt ?

Is it possible to bleed the system on your own? Not ideally no, you need one person to rev the engine and one to control the bleed valve. Don't forget about the slightly delicate bleed valve on top of the stat housing too (assuming later type plastic stat housing).

I've had a go by revving the engine quite high and then running around and retightening the bleed bolt but i'm concerned air will get back in. Yes it might

Would it be better to park on a hill if i'm doing it myself? In my opinion yes, but some say not required.

Sorry for such sill questions = No worries

Take care not to undo the bleed nut on the rad right out when engine is hot.
Reason = hot water and expensive coolant will shower all over you and you cannot get it back in easily under those circumstances (ask me how I know !!)
Read the coolant bleeding procedure in the wiki ^^^^
Check it again after a day or so to make sure you do not have an underlying problem causing air to get into the system.

[California Dreamin]

All god stuff ^^^^^^^^

I would also say under normal circumstances there would be no need to raise the front of the vehicle to bleed the cooling system but in your case: we know the issue is with coolant circulating around the front heater matrix. Therefore, it makes sense that the air is likely trapped somewhere towards the front section of the cooling system.
As a consequence, raising the front of the vehicle a little is likely to aid the purging of trapped air.

Be careful not to overtighten the front rad bleed screw (soft brass)

Use a rag in hand over the screw just in case it sprays.

So it sounds as though the matrix is recieving coolant but it is not properly circulating.
By this we can deduce both the coolant valve and heater flaps are allowing correct operation (coolant and air flow)
The intermittant nature of the heater blower hot air operation does indicate stagnent flow and the most obvious cause to be an air lock but don't discount: water pump impeller issues (turning on shaft)/blocked system/slipping fan belt/head gasket issues.

Martin

[Oldiebut goodie]

Isn't the heater pipework separate from the rad hoses? The heater usually receives heat before the radiator by design. In which case raising the nose will have no effect on bleeding the heater (only the cooling system). My money is on semi - functioning thermostat or impeller on water pump disintegrated.

[California Dreamin]

One bit of important info that we haven't been given yet is: what the temperature gauge is doing? and when?

With an imprellor fault poor circulation would cause high temperatures.
Faulty thermostat (staying closed) also overheating.
Failed open: very slow temperature rise....not going much past a quater on the gauge and only rising after long driving periods.

I suppose another possibility is that a previous owner has removed the thermostat in which case the heater is going to take a awful long time to get warm especially now the temperature has dropped outside.

Martin

[Graham81]

Its flow related, if it works as it should: ie normal hot air from blowers then i would suspect the water pump and how much pressure it is producing.
It could be air, the only way to clear that would be with the engine cold so the stat is closed and forcing pump pressure through the matrix, high revs and the expansion cap off.
Possibly blocked matrix even,
Plumber by trade.

[ANDKAT]

HI Guys

Thanks for the replies

The temp guage is fine, it moves up to halfway which is the normal operating temp on my van, It's not overheated, however the other day I did notice that after I topped up with coolant and started the engine the temp guage went right up off the scale until I started to move and then it dropped all the way back down to cold, it then increased as normal to normal working temp.

[Graham81]

Sounds like water pump, lol just seen your location