Heater Blowing Only Cold Air.

[savage1889]

Hi I have a 52-Toledo 1.9TDI, just recently the blower has started blowing only cold air. I was told that the matrix may be blocked and to remove the two pipes that go to the matrix put a hosepipe on one and see if the water came out of the other, water came out of the pipe as fast as the hosepipe was putting it in the other. Then i was told it may be the thermostat, which i have replaced and not solved the problem. When the engine is warm one of the pipes that go through to the dashboard is really warm while the other one is quite cool, because of this i am thinking that ther is a fault with the matrix somewhere. Just wondering if anyone can shed any light on anything else i could try before having to dismantle the dashboard to rteplace the matrix? or tell me how i can definitely tell that it is the matrix?

 

[Muttley]

Do you have climate control or just manual heater controls?

The heating matrix should be working all the time, the heater system controls the temperature of the cabin air by mixing hot and cold air.

There is a temperature control flap in the system which is attached to the temperature dial on manual systems, and is motorised for cilmate control. It is possible that this has failed in the cold position, either the cable has come off or the motor has failed.

One other possibility is an airlock in the heater matrix pipework.

 

[savage1889]

It has climate control. Would an airlock in the matrix system not be cleared by forcing water through using an hosepipe? Is the motor easier to get to than the matrix or is this also a case of taking the dashboard out?

 

[Viking]

I'm guessing it's the water pump. After a drive, pop the bonnet up and check the hoses to the radiator. If they're rock hard, top one hot and botom one cold, then it's the water pump I suspect.

 

[Muttley]

Hmmm. If it was the water pump I'd expect to see the temperature gauge sounding the alarm first.

There is another point though - is your coolant up to the right level? Low coolant affects the cabin heater matrix first, it't the highest set of pipes.

Airlock is not very likely, to be honest. The pipework is not complicated and there isn't really anywhere one could form.

I've never needed to get at my heater system, but the diagrams I can find show the heater flaps are behind the central console, with the lever arms underneath the ducting.

I'd recommend VAG-com to look for any fault codes associated with the airconditioning system first.

 

[savage1889]

The alarm hadn't sounded before but ive been out in the car today, drove about 20 mins and the temperature went right up to 120 with the light flashing and alarm beeping. does this make it sound more like the pump?

 

[meltonlad]

could be the blades on the water pump are broken. if thats the case you be better off to replace cam belt at the same time. when you are driving it does the temp go sky high ? but then you are just at idle the temp sits at 90 ? then i would say water pump.

 

[Viking]

The alarm hadn't sounded before but ive been out in the car today, drove about 20 mins and the temperature went right up to 120 with the light flashing and alarm beeping. does this make it sound more like the pump?

Yep, water pump mate. As said, time for a cam belt and kit at the same time, as it all has to come off to get to the water pump.

 

[savage1889]

yes at idle it sits at 90, after driving 15-20 mins its up to 120 flashing and beeping. Water pump is only £35 just sounds like a pain to do. Thanks for the help.

 

[Muttley]

Water pump. Pump costs £30, but you need the cambelt off to change it, thick end of £200.