Heater Blowing Cold Air Only

[waynep0]

Please can anybody help me please, I have got a 1997 2.8 ghia galaxy and the heater only blows cold air. The fan motor is working fine but its just cold. the temperture gauge goes to the normal position ( half way ) Please any ideas on what it could be before i freeze!!!

[Nige F]

Please can anybody help me please, I have got a 1997 2.8 ghia galaxy and the heater only blows cold air. The fan motor is working fine but its just cold. the temperture gauge goes to the normal position ( half way ) Please any ideas on what it could be before i freeze!!!

 

Had exactly the same happen other day. Topped the water up a little and it has been fine since.

[waynep0]

Thanks for the fast reply, just checked water leval and its fine, any other ideas?? anybody

[kertrats24]

i suspect this could be many things but i would check aux water pump its a small electric pump on the bulkhead behind the expantion tank you should hear it after you turn the engine off it still runs on for a few mins.

its main function is to pump water round the heater matrix.

[Bigjeeze]

i suspect this could be many things but i would check aux water pump its a small electric pump on the bulkhead behind the expantion tank you should hear it after you turn the engine off it still runs on for a few mins.

its main function is to pump water round the heater matrix.

 

I disagree - it's main function is to keep the water moving to prevent hot sapots. In any event the run on pump will not cause this problem. It sounds more like an air lock.

[chrispb123456]

Hi there

Some things to check.

 

When engines hot and running do the heater pipes running through the bulkhead get hot, you may have to remove the bulkhead extension (scuttle plate) to do this.

If they are cold then you either have an air lock as BJ suggested or the matrix is blocked.

 

If they are hot then the air control doors are not working or jammed

[waynep0]

thanks for your help, whats the best way to get rid of an air lock in the system?

[davewill]

I had this on my Mkll

 

Turned out to be the impellor had failed in the water pump

 

I drove around for around 3 days then suddenlt the temp gauge hit hot and the engine overheated

 

Check the water pump impellor is still in situ

[cyborg]

Hi there,

 

Suggest you get Vag com Or borrow it.

 

As your Automatic climatic am afraid its Eletric's and motors .The systems with dials, its easier mostly cloths wire control.

 

So in meantime Suggest stick on rear heater, open all roof vents, turn off front heater and use heated window control to get you by.Oh and put on your heated seats.

 

There's a number of things it could be

 

Sunlight sensor centre of dash faulty, making system switch to cold air .

Flap motor failure behind dash.

 

 

While you wait for lead check

Fuse Failure Check

F29,5A Electrical system,aircon,wiper relay, Aux heat ,heated front screen

F34,25 Heater blower

 

F15,30A cooling fan

F16,30A Thermo,cooling fan 1

F18,5A Thermo Switch cooling fan 2

F28,10A Abs,Thermo Switch

 

Relays

128

Edited November 10, 2010 by cyborg

[john1doherty]

hi this has happened to me as well and as the above post said it turned out to be the impellor in the water pump my car overheated as well and the water bottle was full and there was no air locks either, check out the water pump before you cook your head and do more damage. the water pump impellors are plastic but the pump can be replaced with one with a steel impellor these can be picked up for around

[waynep0]

Thanks for everyones help, drained system today and refilled so no airlocks but still no heat!! so how easy is it to change the water pump?? any tips or list how to do it? thanks

[waynep0]

Also to add i could not hear the run on pump going so took off the pannel under the wiper motor but for the life of me i could not see the pump!!! imust be blind but to my defence it did chuck it down with rain so put pannel back and went inside. Where can i find this pump because i can not hear it running at any time, would this not working make the heating blow cold only??

[chrispb123456]

Also to add i could not hear the run on pump going so took off the pannel under the wiper motor but for the life of me i could not see the pump!!! imust be blind but to my defence it did chuck it down with rain so put pannel back and went inside. Where can i find this pump because i can not hear it running at any time, would this not working make the heating blow cold only??

Hi there the run on pump usually on bulkhead but on V6 may be on bracket on rear of cylinder head see no. 9 on picture

 

Gives you an idea what your looking for.

[waynep0]

Latest news, checked all fuses, all ok. Took off the aux pump and got it working, can hear the electric heater flaps opening and closing and guess what STILL no bloody heat from the heater!! also when hot the top pipe on the expansion tank yhere is only a small trickle of water coming through. All pipes are getting hot. Please any ideas? could it be the water pump? how easy is it to change the pump? thanks

[sotal]

My guess would be air lock (still) or blocked heater matrix.

 

When you refilled did you let the car run for 10 mins without the coolant cap on? This usually helps get rid of any air.

 

Next thing would be to disconnect the two pipes that go through the bulkhead and put the hose (mains pressure) into one side and direct the other side into a bucket, this should clear any blockages and prove that water is flowing through the matrix. Have a look for brown sludge or flaky bits in the bucket. If it does have quite a bit of muck in then it may be worth using a descaler type product as well.

Reconnect the pipes and see if that sorts it.

 

The aux pump helps circulate water to the rear of the car and keeps water moving around after the engine is switched off - it won't make any difference to normal heating when the engine is up to temp.

[waynep0]

yeah run the car for about 20 mins with no cap on.will try flushing out over the weekend.thanks

[chrispb123456]

Latest news, checked all fuses, all ok. Took off the aux pump and got it working, can hear the electric heater flaps opening and closing and guess what STILL no bloody heat from the heater!! also when hot the top pipe on the expansion tank yhere is only a small trickle of water coming through. All pipes are getting hot. Please any ideas? could it be the water pump? how easy is it to change the pump? thanks

Hi there

Have you just bought the car or has this occurred over time.

 

In all your posts you have never mentioned about any overheating or water loss, as that is the engine water pumps function to circulate water around the engine and radiator and also through the heater matrix, if all pipes are hot after a run and no signs of overheating I would say the engine pump is working.

I think what you need to establish is the water actually flowing through the heater matrix.

 

On the diagram I sent you, you will see flow and return pipes no.11 & 16 you need to remove 16 from the electric run on pump, plug or hold finger on pump inlet, get an assistant to top up water bottle and than start engine, water should then be pumped from the hose you disconnected.

 

If nothing comes out remove hose 11 and connect a garden hose and turn on slowly, you should be able to send clean water through matrix, if nothing comes through matrix is blocked.

 

The purpose of the run on pump on your car is to prevent hot spots when engine is turned off the pump continues to run for a few minutes then switches off.

What was the condition of the water which you drained out, ie was it rusty, just clear water, or water with coolant/antifreeze.

 

As for the small trickle on the water bottle return pipe that is correct.

Edited November 12, 2010 by chrispb123456

[waynep0]

Yeah just got the car, havnt been on a long trip yet so no over heating. its not losing any water, water was a crappy brown colour. how would i know if i had an air lock? and how would i get rid of it? thanks

[sotal]

If water was a crappy brown colour then you probably have a build up of crap which is blocking or restricting flow through the matrix. If it's like other cars I've had it blocks up first as the holes are quite fine.

 

If it was my car I'd be emptying it and flushing everything through, matrix radiator etc until everything is free flowing and clear, then refill with fresh coolant

[chrispb123456]

Yeah just got the car, havnt been on a long trip yet so no over heating. its not losing any water, water was a crappy brown colour. how would i know if i had an air lock? and how would i get rid of it? thanks

Oh dear that don't sound good the brown colour could be endless amounts of radweld or the outcome of running with no coolant/antifreeze, or has boiled up at some point and loosened up sediment laying in the cooling system.

 

You need to get off as many hoses as you can and ideally remove thermostat housing and flush out with a hose or careful use of pressure washer.

When your done clear water is all you should see.

 

Following the procedure in my previous post ie removing hose 16 etc will expel any air in the heater although this shouldn't be necessary if the matrix is clear

Edited November 12, 2010 by chrispb123456

[waynep0]

Just a quick update, had today off work so took all the matrix and radiator hoses off and flushed it all through so it was running clear water, took out the water pump to check, it was ok but it was the one with the plastic impeller so whilst it was out i got a new metal impeller one and fitted it, refilled system with antifreeze/ water and ran car for 20 mins with the cap off and guess what HEAT lovely Heat!!!! I would just like to thank everyone for their great help, could not have done it without you.