Hi I have been reading lots of threads regarding this problem but just don't know what to try first.

I have a 2004 GSI with ECC.

Car seems to heat up fine so I guess no problems with thermostat.
When car is up to temperature, I left the car running and had the heater on HI and fan on 7, just lukewarm air came through (doesn't matter where i have air blowing, foot well screen or face).

The 2 pipes going into the matrix, the one on the right was extremely hot to the point where it was burning my hand, but the left one was cold/lukewarm. Would this lead you to believe there is a blockage in the matrix.

I am contemplating trying to flush the matrix through but on this engine access is very tight to get the pipes undone from where they come out of the engine, any tips?

Would it be easier/possible to get to the matrix inside and touch that to see if its hot before i try to get these pipes off?

Could it be a problem with the servos instead, what exactly would i be looking for?

Cheers in advance