A4 B5 TDI AFN Lack of Heat from matrix

[quattro101]

Heads up guys!....I am getting only luke warm air from my heater whilst on 'Hi' setting. Have checked the flap motors and all seems well!.......im guessing that the system was neglected at some stage in the vehicles life as there is a brown coolant stain below the coolant temp sensor flange on the side of the block and the reservoir was also stained inside when i got the car, Its covered 160k. I am reluctant to do a full dash strip down and rebuild to change the matrix and was wondering whether anyone has attempted filling the matrix with a good rad cleaner...leaving it a day or 2 and then blasting the crap out with an airline!??....experiences and ideas greatly appreciated as Winter approaches!

Cheers ....Steve

[towcestervag]

get some cooling system cleaner from your local motorist shop and flush several times

[quattro101]

Thanks for the speedy reply....yes i will be giving that a try!.....anyone got a diagram of the coolant flow on this vehicle. I want to know which heater stub the hose from the back of the cylinder head connects to......not sure if mine are connected correctly.

thx

[towcestervag]

the hose to the heater matrix with small bleed hole in top goes to the drivers side hose on right hand drive and this hose goes to the back of the head

[Zenerdiode]

the hose to the heater matrix with small bleed hole...

...and if not bled correctly the matrix won't get any hot coolant. The top of the matrix is actually slightly above the coolant reservoir. There are two methods for successful filling/purging. A VW tool exists that is a tube about eight inches long that screws into the reservoir so you fill beyond the max, up the tube above the top of the matrix. You then back off the hose-clip on the hose with the bleed hole; withdraw the hose until the bleed hole is beyond the matrix stub (but don't pull the hose off all the way) and purge all of the air out of the system.

Without the special tool, unscrew the two or so mounting screws and have a helper raise the reservoir as far as the hoses will allow. This also gets the level above the bleed hole.