Heater Core or Heater Valve?

**aleccolin** · 10-27-2008 01:56 PM

'01 S4, everything is normal except that I get very little heat in the cabin. It blows luke warm at best.

I'm thinking either a mostly blocked heater core or a bad heater bypass valve. I haven't found anything on these two being a common problem, but maybe someone has had the same issue.

Any help is appreciated.

**hans j** · 10-27-2008 10:58 PM

I have seen a few heater cores get clogged with junk. You can try flushing it out but in the end you may need a new core. We are trying a couple things at the shop to see if we can get them cleared because... basically they suck to replace.

**aleccolin** · 10-28-2008 06:20 AM

Yeah I thought about disconnecting the lines and running some sort of solvent through on a loop, try to get most of it out, but if I'm not sure that's actually the problem I'd rather not go through all the trouble first.

**s42k5b** · 10-28-2008 08:03 AM

it could be ur Thermostat or your coolant temp switch. Try changing the CTS first.

**aleccolin** · 10-28-2008 07:53 PM

Originally Posted by s42k5b

it could be ur Thermostat or your coolant temp switch. Try changing the CTS first.

If it were my thermostat I would expect my coolant temps to be doing some weird shit. A faulty coolant temperature sensor would throw a code, or at least cause some kind of abnormality. So far everything is normal except for the lack of heat, which makes me think warm coolant is not flowing through the heater core in a normal fashion, so either malfunctioning heater valve or partially blocked core.

**rms-s4** · 10-28-2008 08:30 PM

find the two hoses that go to the heater core on the fire wall. let your car warm up good and touch both of them. if they are both the same temp (to the touch) id say its something else. if one is hot and one is cooler the core could be clogged. i had a problem with a customers a4 but that flush stuff in it but ended just puting one in. and if it that. it freaking blows to do.

**aleccolin** · 10-30-2008 07:15 AM

Originally Posted by rms-s4

find the two hoses that go to the heater core on the fire wall. let your car warm up good and touch both of them. if they are both the same temp (to the touch) id say its something else. if one is hot and one is cooler the core could be clogged. i had a problem with a customers a4 but that flush stuff in it but ended just puting one in. and if it that. it freaking blows to do.

Yeah I intend to do just that, haven't had the time yet. Do you recall seeing a heater valve, or does it just circulate through the heater core ALL the time?