Odd heater behaviour

[gords]

Now that's a bit cold, I've started to use/want the heater straight away.

As usual, it doesn't chuck out heat immediately ... but the car warms up (temp guage to normal) and still it's blowing out completely cold air. Drive for 10-15 minutes and all of a sudden, out comes hotair, I mean straight away, not that it starts to blow out warmer and warmer air :?

So, any ideas? The last time it was in the garage they reckoned that the heater matrix must be blocked because they had trouble getting the cooling system filled. If so, why does the (full on) heat start suddenly?

I'm assuming that it's a pig of a job to get the matrix out?!

[Wanderer]

Dash out :(

[TimM]

Could it be filled with anything to remove the blockage, and then drain it out?

(I'm only guessing here)

[Wanderer]

Gords,
Is the thermostat working ok?
I can't see that a blockage would clear quickly and reappear each time whereas the thermostat sticking or an air lock might cause it.

Take the hoses off and try back flushing (gently) the heater and see what comes out.

[beast5680]

the recirc air thing isnt getting stuck is it? would that cause a problem maybe?

[hobbit]

I got another heating prob, the opposite of youra, pleanty of heat, no blowers. The result is the same though dash job.

ALthough been thinking of working out a way of blowing air into the intake on the top of the motor

[gords]

Is the thermostat working ok?

The engine warms up normally, going by the temp guage, and sits a smidge below the middle. Doesn't that indicate that the thermostat is OK?

The temp gets to normal way before any heat comes out of the heater :roll:

[petergalileo]

Thermostat test,  Start engine, then go open the bonnet.  Keep hold of the top rad hose.  It should stay cold until just before normal operating temoerature, then it should get hot almost instantly.  If it warms up slowly with the rest of the engine the thermostat is stuck open.

It could be an air lock.  I dont know whether discoveries suffer from this but on some cars, the hoses to the heater run down to the matrix then the matrix sort of points upwards creating an airlock.  When the engines warm try sqeezing the top hose loads of times, this normally cures that.

If its a blocked matrix, Going by the other replies you are going to have to take the facia off the car to get to it :(

Peter