Hi guys,

new to this forum but not to the cars. I am Vincent from Germany, Cologne, 35 years old and own a 2008 TDV8 3.6. Nice meeting you guys!

I kindly ask for your help regarding a heating issue with my car. I searched through all the WWW but couldn't find a solution yet.

Issue: the car doesn't blow any warm air through the front and back vents with temperature at 28 degrees and dial to red. It doesn' t matter if it is on "auto" or manual.

What I already have changed:

1) heater core (original part)
2) heater control valve (original part)
3) thermostat (original part)
4) electric coolant pump (NRF)

My car doesn't have a remote for the fbh, hence no changeover valve. The car gets to temperature and the gauge stays in the middle. The pipes to the heater matrix get boiling hot when I turn the dials to 28 degree and cold when I turn them to 16 degrees. I bled the system I believe like a thousand times and am having no issues with coolant loss. If I pressurize the system it doesn't loose any pressure at all.

What's really interesting, is that if I turn the dials in the front from hot to cold, the back heaters (turned to hot) are blowing steaming hot air! If I turn the front to hot and the back as well, I only get cold air.

Right now I have taken apart the dashboard to see if the motors are working fine, but I really can't find any issue with them. The flaps are moving manually.

Questions:

1) which blend motors are responsible for the temperature regulation? (it's a LHD car)
2) do you have any other ideas where to look?
3) could it be the hvac control unit itself?

I have an IID tool but don't get any hvac faults. The live values are as following:

- evaporator temperature if set to cold (3.7 degrees), if set to hot (32.5 degrees)
- coolant temperature 92 degrees
- cabin temperature readings are plausible

Sorry for the long thread, I hope you guys can help me out.

Thank you very much in advance.

Best,
Vincent

Hi Vincent, I don't have much to offer you, buut have a similar issue. 2010 5.0 N/A. My 5th L322, no trouble codes present. 215k miles

I had been chasing some coolant loss and have swapped a couple of pipes, the coolant distribution valves and the water pump, which, fingers crossed, seems to have addressed the coolant loss, but my heater still behaves strangely.

Only in the drivers corner of the car though. Passenger front, passenger rear, drivers rear behave normally, but drivers side front will deliver heat normally for a short while after startup, then go completely cold, unless I crank drivers side heat up to very maximum, when I get some, but low, heat. Anything less than full on the dial is ambient coold.

Following, hopefully we can get some help!

I keep having issues with my hvac as well. I have posted a thread on my troubles.
After replacing the heater control valve again I now have better control of the temp in the cabin but it's not as good as it was originally. The after market valves are considerably smaller than the originals, I'm wondering if this is responsible for the lack of fine control.
I also had bizarre control issues with the rear fan suddenly going to full blast whilst I was under the steering wheel fiddling with the FSR. Manipulating the wiring to the rear fan has cured it for now but I'm still worried that I'll find a flat battery one morning.
I looked at replacing the heater controls but am loath to spend money when I don't know the cause of the problem. For now it's working.
Sorry not much help, keep your expectations in check. 80% is pretty good, perfection will blow your mind with these great cars. 2007 3.6 TDV8
1979 Mini Special
1988 Yamaha FJ1200
!952 BSA Gold Flash