renault megane 1998 s regscenic heater

[domscams]

my heater does not work, i have flushed it out the matrix is getting hot water to it and back out, the therm is ok , what do u think

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[auldyin]

Sounds like the core of your matrix is gunged up and the water is simply flowing round the edges of the matrix and back out. I used to remove the matrix, unsolder the head and use a dipstick or similar to unblock the narrow passages in the core, resolder the head back on and "hey presto" a nice warm car again. You could visit a radiator repair shop and they may confirm it is a blocked core and offer you a recon replacement! I never have found any 'flushing agents' from the accessory shops that could clean out a heater matrix successfully.

[domscams]

Thanks for the reply, coup[le of questions though, i took the two hoses off the engine side and blasted out with a hose both ways and the water flowed well and quick as if there were no blockages, When you sorted yours, how easy was it to get to?

thanks

[auldyin]

the reason that water flows well and quick through the heater matrix is because it bypasses the blocked core, and simply runs in one pipe, across the top of the matrix and out the other pipe. If the core is good then hot water will fill the tubes in the core enroute thus giving you your heat. Sorry, but I've never done this job on a Renault but it has always been a frustrating job to do on various cars that I have done. The actual overhauling of the matrix is simple enough, but getting it out fom under the dash without accidently disconnecting some wire or cable, then finding when you put it all back together, the heater works great, but your instrument panel no longer illuminates. Saying all that, you have job satisfaction plus save a few bob!