Is it time to change heater core?

[edzha90]

Hi there,

I took my VW passat b5, 2000 year, 1.9 diesel to local garage. They done flush for cooling system (including, heater core and cooling radiator etc.) changed thermostat. But the heat is really poor and when I am driving fast above 100km/h it slowly gets colder and colder.

Is it plugged heater core?



Also I checked temperature with VCDS lite, sometimes it showed 98C, 93C and then 90C(when car was not driving)


What could be a problem ?

[Flash2]

Did you check for faults in the heater/aircon system with VCDS? Perhaps the stepper motor that controls the temperature flap on the heater box is faulty.
You can check operation of the control motors via the measured values too but I don't remember what the value blocks are.

Jim.

[edzha90]

Did you check for faults in the heater/aircon system with VCDS? Perhaps the stepper motor that controls the temperature flap on the heater box is faulty.
You can check operation of the control motors via the measured values too but I don't remember what the value blocks are.

Jim.

I haven't checked the heater/aircon system in VCDS, where exactly do I need to check ?

How do I know if the temperature flap is faulty ?

[Flash2]

The heating is at diag address 08. Check for trouble codes there. There will probably be a measured value that will display output from the flap position motors feedback sensor. I don't know what the value block number is, you'll just have to play around a bit. You can use that to check that the motor is moving through it's full range. Monitor the reading in the measured value while operating the temp control (slowly across it's full range) and make sure the value changes with the control.

You could also try using basic settings which will operate all the flap motors across their full range to store the end stop positions in the ECU. In fact, I'd try the basic setting first and see if the temp output from the heater changes while it's in progress. Get the engine up to temperature first obviously.

Jim.

[edzha90]

I was checking with VCDS but cannot understand which one I need to check. I have found 07 all of them were about temperatures, not sure what temperature needs to be there.

also I went to another garage, they told me that it could be bad waterpump, thermostat or big radiator. Because the pipe what goes to radiator (the front one) bottom side it's cold, isn't event warm. So that pipe is full of junk or something.. he said that may occur a heating problem, any ideas how to clean, do I need to take off the whole front ?

[zollaf]

in the engine bay are 2 small pipes going to the heater matrix. they disappearinto the bulkhead somewhere behind the engine.after a run, do these get hot.

[edzha90]

They got warm. The pipes what goes to heater core on right side are warmer than the left side pipe.

The pipe what goes from engine into the cooling radiator (the big radiator on the front of the car) is cold, is not even warm when engine temperature is 90C when I done some bending(squeezing) on that pipe, my heating temperate has improved, I had warm heat.. so I think the big radiator might be faulty, because the bottom side of radiator where the pipe goes in it's cold.

I would be happy to have that heating for longer period, because once I am on motorway the warm heating goes away..

is there any option that I can check on VCDS-lite about heating ? like faulty codes etc. ?

[martin1810]

Buy a cheap infra red thermometer and check the radiator and pipe temperatures. You may just have an airlock.

[danoid]

Did they bleed your system?

Sounds like they didn't, as that can be a cause for no heat out of the vents.

Check the last photo and the last paragraph of text at the bottom, follow this and see if it improves Coolant flush and bleeding - VW Passat TDI B5 | VW TDI forum, Audi, Porsche, and Chevy Cruze diesel forum

[edzha90]

I got heating but not the best, but it's okay for current outside temperature. I changed cooling tank lid (thought it can be something wrong with that, also someone told me that)


I did found out that if I drive in high rmp my heating is getting warmer and warmer... what could be that ?