You know what this means, right? You are now the expert on the subject. In the future, all heating inquiries will be routed directly to you...

 

Hooray!

I think the system does it (if in Auto).

By way of example, it doesn't put heat into the cabin on a cold day until the coolant has warmed, then puts as much in as it can. So, that's DCCV shut to open.

The underlying problem is that the (Bosch) valve fails. The next problem is that the CCM/RCCM cannot cope with a short circuit. (I suppose I could mention the hose life or lack of, too.)

Now, in the summer (what's that?) it might still be worth cycling the DCCV by turning heat UP briefly now and again.

 

Are you sure about the sequence? I tried this on my '02 but no joy.

 

I'm not sure. I read about it but actually never had to try it since I have IDS...

I just ran down and tried it and...nada on screen, just normal temps on screen and all the servo motors running/calibrating maybe?

Maybe it only works for the LS ACCM's... 06+ MY for sure per the document I attached earlier in the thread. I read about this self test being performed on the 00-02 LS also.. (coolant above 120 deg, key on, cabin temp between 32 - 90 deg F) if no codes stored screen will remain blank but you'll hear the servos recalibrating... If codes they will show on screen.

Press defrost to erase and blue cooler button to exit test but retain DTC's.

 

Any thoughts on what brought the aux pump back to life? The relay sockets? Or fixing everything else (failed thermostat and DCCV) restored some input required to command the pump on?

 

Here's my thoughts:

Mainly I think it was a loose R5 relay socket spade terminal. (I think spade #2 seemed to have the biggest gap)

Second thought is just maybe the aux pump commmand is not sent unless the ACCM senses the car is in motion and is fully warmed up.

Who knows, could also be the new DCCV/thermostat replacements as you pointed out.

All I know is I have nice toasty heat, even at idle when driving (I saw the temp bump up on my digital gauge in the vent when car is stopped at red lights) and with 252K miles on the clock I consider that a big, big win!

The wife was in the car last night and lowered the passenger side to 75 as she said 85 is too damn hot!

 

Hi Guys,
Just like to say thanks for all the info on this thread as I've been having/am still having problems with my V8 not giving any heat out in the cabin.
But like you, I've got the DCCV out and will bench test it, also got no voltage at the aux pump, but after reading everything you've done I'm pretty sure I'll have it sorted shortly.
Thanks again for a great thread.