Heater not working

[Gerry Attrick]

Hi. After hours in the garage, I cannot find out why I can't get the heater on my Saab 9-5 working.

My radiator sprang a leak on Boxing Day. I've fitted a new one but I cannot get the heater to blow hot air. I assumed it's an air lock problem. I've drained and refilled the system a number of times according to the Haynes manual. I've checked for climate control problems by pressing 'auto' and 'stop' and got no codes showing. I've disconnected the hose to the matrix to let any air out. I've taken it to a local garage so they can put a vacuum thingy on it to suck out the air, and they say there is still air in there which won't come out. I've held a bucket of coolant in the garage roof and connected it in turn to the feed and return lines from the top tank. None of these appear to make any difference.

Has anyone got any suggestions?

I'm wondering now whether the water pump is shot. If it were not pumping, could this explain it? If it were not pumping, could this be the cause of the radiator failure (engine boils and pressure blows a hole in it). Or am I just clutching at straws?

[Pumaracing]

Fill the system and let the car idle for a couple of minutes with the expansion tank cap off. Any air ought to come straight out. Top up, put the cap back on and run the engine until the coolant is up to temperature. Are the pipes to and from the heater matrix hot? If so then it's not an air lock. It could just be the heater flap not moving.

[Gerry Attrick]

Pumaracing said:

Fill the system and let the car idle for a couple of minutes with the expansion tank cap off. Any air ought to come straight out. Top up, put the cap back on and run the engine until the coolant is up to temperature. Are the pipes to and from the heater matrix hot? If so then it's not an air lock. It could just be the heater flap not moving.

Thanks for the suggestion. I have tried that, at some stage over the past couple of weeks. No bubbles appear. Both pipes are hot, but the climate control self check says there are no problems with the flaps etc. There is plenty of air coming out of the blower, but it's cold. I'm assuming that although the pipes to and from the matrix are hot the water is not circulating, and once the blower has extracted the first bit of heat from the matrix it stays cold. Hence my current theory that the water pump is shot. What do you think?

[HRG]

Crack one of the matrix pipes open a bit with the engine running and the heater control to full heat. That should allow the air to bleed away. Usual disclaimers about burns apply.

[Gerry Attrick]

HRG said:

Crack one of the matrix pipes open a bit with the engine running and the heater control to full heat. That should allow the air to bleed away. Usual disclaimers about burns apply.

Thanks for the suggestion. I've also tried that. I disconnected the return line from the matrix. I got plenty of water from the engine side but nothing from the matix side.

[HRG]

That begs the obvious question, what happens if you disconnect the other side?

[rev-erend]

Perhaps the matrix is blocked or has an air lock.. you could try a pressure flush with a hose pipe (remove both hose from engine and put garden hose in one side and hold your hand over it so no pressure escapes..

You should see water emerge from the other hold else it's really fubar'd.

[Gerry Attrick]

HRG said:

That begs the obvious question, what happens if you disconnect the other side?

I haven't tried that one yet as it's such a pain to remove these silly bits of spring metal they call hose clips. I'll try that tonight.

[HRG]

Could be the heater control valve, common enough failure on the Griff.

[Gerry Attrick]

rev-erend said:

Perhaps the matrix is blocked or has an air lock.. you could try a pressure flush with a hose pipe (remove both hose from engine and put garden hose in one side and hold your hand over it so no pressure escapes..

You should see water emerge from the other hold else it's really fubar'd.

Thanks Rev. Something else to try. I doubt it's furred up too badly as the heater was working fine till I replaced the radiator. I was hoping that pressure flushing the system with a couple of gallons of coolant hanging from the garage roof would have done the trick. Perhaps 6 bar of pressure from Thames Water will give it something to think about.

[Pumaracing]

Gerry Attrick said:

Pumaracing said:

Fill the system and let the car idle for a couple of minutes with the expansion tank cap off. Any air ought to come straight out. Top up, put the cap back on and run the engine until the coolant is up to temperature. Are the pipes to and from the heater matrix hot? If so then it's not an air lock. It could just be the heater flap not moving.

Thanks for the suggestion. I have tried that, at some stage over the past couple of weeks. No bubbles appear. Both pipes are hot, but the climate control self check says there are no problems with the flaps etc. There is plenty of air coming out of the blower, but it's cold. I'm assuming that although the pipes to and from the matrix are hot the water is not circulating, and once the blower has extracted the first bit of heat from the matrix it stays cold. Hence my current theory that the water pump is shot. What do you think?

If the water wasn't circulating then the pipes wouldn't be hot! Or at least they wouldn't stay that way long with the heater fan turned on as the matrix cooled everything up and downstream of itself. I'm sure it isn't an air lock or the water pump. It's a coincidental problem with the flaps or climate control system since you changed the rad. You need to check visually that when you select for hot air the flap moves as it should. How you get under the dash to do that on that car god only knows. Maybe a well trained ferret would be a wise investment. You can't have my little Verity though.

[Gerry Attrick]

HRG said:

Could be the heater control valve, common enough failure on the Griff.

I'm not 100% sure how the system works on the 9-5. As best I can see, there is no heater control valve as such. All the coolant appears to go to the matrix, and cabin temperature is controlled by flaps which direct or by-pass air over the matrix. The only valve I can see in the engine compartment is one which is activated when the aircon system is trying to cool the cabin. In this case, the coolant by-passes the matrix completely and all the hot coolant is circulated under the bonnet. This appears to be OK as the by-pass hose is cold and the supply and outlet hoses are hot. There could be a heater control valve buried somewhere under the dash that I've not yet come across - does anybody know? I assumed I was checking the operation of any such valves when I activated the 'self check' and got no problems.

[megane225]

sometimes fins from the pump are rusted and cut off the propeller, and the flow minimizes but that will lead you to overheating, depents again on the weather and driving conditions. a blocked elbow or hose again might be the reason .

[Steve_D]

How are the air flaps driven?

Some systems use the linkages as you move levers but I suspect yours may use vacuum. In a Range Rover they are moved by vacuum bellows but these are controlled by an electric valve in the vacuum line.

Do you have a vacuum leak or a blown fuse in the control circuit. I would not believe what the computer says, untrustworthy blighter them.

Steve

[Gerry Attrick]

Still can't sort the b1##dy thing!!! I've looked in the footwell, and the system uses levers to move the flaps, but these, I assume, are just to direct air to the footwells, screen or face. This part appears OK as I can feel the changes and can hear the motors runing. The fan speed also changes with the control switches on the panel, and with the temperature difference between the setpoint and the cabin temperature.

I've noticed that when the car is started up, it takes long time for the inlet hose to the bypass valve to heat up and even longer for the return hose to heat up. This suggests to me that the water flow through the system is slow. Does this mean that there is an air lock - my original diagnosis - or is there another valve buried under the dash somewhere that limits or by-passes the flow to control the temperature? It was this that made me consider a broken water pump, but there is no sign that the engine is overheating even when left idling for half an hour.

The other thing I've noticed is that it doesn't appear to be reaching pressure as it's quite easy to squeeze the various hoses. I'm asuming that this is because there is an air pocket inthe system and I'm squeezing air not water.

I've got to get this sorted soon. My wife has resortd to wearing a blanket over her legs: more like a 1902 De Dion Bouton than a 2002 Saab.

[megane225]

check ytha thermostat.if it stays open then the car needs long time to reach working temp.if there was mud in the rad then clean the system.try to put o hose in the heater matrix and put some water in it to see if its free. if you dont have a flow then its the pump or blocked hose going to the heater.is the car on straight roads cools down? from where the problem began?