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Discussion Starter · #1 ·
Multi Message for Heaters not working etc.

Checking cooling systems
Checking you cooling system for overheating etc, theory is the cooling system is sealed and coolant is checked through radiator or header tank cap, essentially as the engine warms up the coolant in the cylinder block and head rises, and goes up the top hose to the top of the radiator, it goes down through the radiator tubes and is cooled by incoming air and fan control, the radiator is a heat exchanger, the circulation is by the water pump, that has an impella so the coolant goes to the middle of the pump and the impella throws it out centrifugally back up to the engine, also the heater radiator feed comes from top of the head and returns to water pump area...the temp is controlled by a thermostat, usually located at the engine end of the top hose...


The Radiator cap is also quite important as it has two valves on, a pressure relief valve and a vent valve, problems with the system are coolant leaks, thermostat faults, radiator blocked or leaking, heater radiator blocked or leaking, air locks, fan problems and water pump, the electric fan usually comes on when the temp gauge is well over the middle of the normal..to test the fan run the engine up and wait until the gauge gets pretty high, if it gets too high or in the red the fan isn't working, you can normally join the fan switch terminals together to test fan, if not working check fuses and relay, can also hot wire the fan motor to see if it works, check to see if you can turn the blades with your hand, the thermostat sometimes might get stuck open or shut, if it's open it will not get hot enough, check gauge, if it's stuck shut it will boil up, run the car up, when the engine gets hot the thermostat should open and the top hose and radiator should get hot, the top of the radiator will always be hotter than the bottom...check all hoses getting hot to make sure coolant circulation...i have known the water pump impella to fall off stopping the circulation...make sure the right radiator cap is fitted, their are different pressures..make sure you have anti freeze in the winter, in fact all year round as it contains inhibitor to reduce water corrosion of the head and block etc...
Coolant boils at a higher temperature at higher pressure, so if it's pretty hot and you take the cap off it can gush our as you have reduced the pressure and caused it to boil, be very carefull taking cap off if it's hot...if you find a load of gunge in the radiator it might just want flushing out, or head gasket problems, especially if there is oil in the water, or indeed water in the oil, a chemical test can be carried out for head gasket problems...the cooling system can also be pressure tested for leaks etc....i have know a cooling system to boil up due to the airways in the radiator being blocked, if you have an air lock so the coolant wont circulate try running it up with the radiator cap off and squeezing the hoses etc to try to get rid of it.

If the heater blows out cold air, its usually the thermostat stuck open, the matrix blocked or an airlock in the heater hoses. feel the heater hoses when the engine is hot, they should both feel the same, if one is hot and one cold the matrix is either blocked or you have an airlock in the hoses. May have to carefully undo the outlet hose, ease it off and let the air out, do it when radiator /header tank cap off. If the Matrix is blocked take both the hoses off and try to flush it out with a garden noise. Also check under dash see if there is a water valve and its working properly, also check operation of heater controls, look under dash and see there doing what they should, by turning and watching.

If the heater blower doesn't work, check fuses and any relays that it might use, the circuit usually is, ignition feed to fuse, fuse to motor, motor to resistor pack and from resistor pack to switch, switch to earth, so with a circuit tester you can check for power at various points. if the motor only works on fast speed suspect the resistor pack. Test circuit before wasting money on new bits.

If the heater motor sounds noisy it's usually a sign it wants a new motor, they can get clogged up with leaves etc..if you see and signs of anti freeze up under the dash or on the carpet etc, it's either the hoses leaking or more likely the matrix is leaking, which can be a big job. also its worth checking the heater vents, like pour water in the grill in front of the windscreen and it should run out usually behind the front wheels on both sides, if it doesn't the drains are blocked, and some water could find it's way inside the car
Well i hope this helps someone out there from Fred in Essex. 2016.


g4vvq1983, Yesterday at 2:06 PM
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Hi Fred
Bought my daughter a corsa c six back in may previous owner said heater didn't work but only now she is obviously complaining my fault I should have looked at it during the summer
So today I drained the cool and took the 2 hoses off matrix inlet and outlet and flushed through expecting a blockage but flushed through fine from dirty rust coloured water til it ran clean
Built back up and replenished cooling system with clean water and some Wynns flush ran up to temperature bleeding system with cap off squeezing hoses noticed inlet and outlet to matrix both warm to hot but still no heat
Left it running for the flush to work still no heat let it cool down and drained replenished with new antifreeze mix bled back up and run up to temp still no heat from blowers etc
Think I will change stat as all system seems warm temp gauge fine but no heat possible stat stuck open?
 

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Discussion Starter · #5 · (Edited)
Well you can flush it out in situ, just take the hoses off it under the bonnet and put a garden hose on it, flush it both ways, i would only change the matrix if its leaking...regarding the temperature well if the temp gauge goes up to the normal place i wouldn't worry about thermostats...you dont tend to get much heat out of heater with engine idling...

If you want to change the matrix i would personally look under bonnet see which sides the pipes go in, i think its passengers side, in which case i would take the n/s glove box out and have a look in there where the heater is, you might be able to take some screws out up there and pull it out, depends how the pipes that go through the bulkhead are fixed to heater...worth a try....make sure all the controls are working properly, especially the temp one....

Ah right i read message again, looks like you done most of it, well if both the heater pipes are fairly hot and temp gauge shows normal i would suspect the controls not working properly....have a good look at the temp control......Fred.
 

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Discussion Starter · #7 · (Edited)
Well i would just look where the cables go on the heater and turn them and see what happens, you might even find the outer cable has come out the clip or something, pay most attention to the temp control, i think all it does is move a flap, i dont think there is a water valve on it, might want to look at the cabin/pollen filter, if the air cant get in it cant get out, but i assume it does blow out cold air.......Fred.

Hi Fred I will have a look at temp dial on control anal admittedly don't know what I'm looking for other than it must move a cable and move a heat flap?
Thanks Jon
 
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