I have a 2005 STR with 72K miles. The DCCV was changed at 54K miles because of a small seep, coolant also changed. The A/C and heat have always worked fine. Car temperature runs perfect and has never over heated. I have a thermostat but have not swapped it out yet. Not sure it's causing any problems??

Now I have zero heat of any kind. All vents are the same. I have run the automatic climate control up and down to exercise the DCCV with no affect at all. Coolant looks great and the level is stable and full. Have not had time to check if the DCCV outlet hoses are hot or not.

Could it be a burned trace on the RCCM? Brutal has stated that he has never had a car with navigation burn out the RCCM so maybe I am grasping at straws here?

Thanks for a great list!!
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If the DCCV fails it is usually one side. If you have no heat on either side rule out the DCCV. If the RCCM fails it doesn't close off the coolant so you would have heat on both sides so rule that out.

You changed the DCCV so check the fuse, connections and the wiring harness. The thermostat would have nothing to do with it but change it anyway. I couldn't believe the difference on my STR when I changed the thermostat.

This advice is worth exactly what ya paid for it...

 

Fuse and power seem to be OK. I am leaning towards the AUX coolant pump right now. Since both sides vent temperatures are fine and the A/C is good I don't think the DCCV is causing my problems?

Thanks for the RCCM tip!
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I know this vehicle has a lot of "smart" stuff on it, but I'm sure it still has the good ol'fashion heater core right? Just a thought.

Edit: Oh and also the switch tends to fail on some Volvo's and Fords... A tech buddy said they are little plastic "catch" switched that can fail. Not sure if that's the case here or not due to it being electronically controlled thought, and now that I think about it, disregard that last idea... lol.

 

I have considered the heater core but I have had the car since 32K miles and have flushed and changed the coolant. I also had two small pin hole leaks in heater hoses after that that required draining the coolant to fix. Everything was very clean and I flushed it several times.

It's possible but unlikely??
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A little more information. The AUX coolant pump is run off a relay so no fuse. The relay (Number 7 if you want to know) is in the front power distribution panel under the hood. I have 12V going to the relay. I swapped it with one beside it that had an identical part number. No change. So I think I need to check if the pump is getting power and is the pump running. Hope to get to that this weekend.

I also dropped down a few gears and drove the car at 3000 RPM for about 7-8 miles. Hoping the mechanical water pump would push coolant better into the heater core. But no change. I have read when you have no heat to operate the engine at a higher RPM to get heat.

The hoses going to the DCCV are warm/hot and seem to be different temperatures. So still not sure about the DCCV.

I wonder if a blend door is stuck??
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I have cycled thru all the different vent positions and all the blend doors are working correctly. So I think it rules out any blend door problems. On to the AUX pump itself.
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I had a problem like this with one of my other cars! it turned out to be a air leak on one of the sealing o-rings on the engine which was not leaking fluid but letting air into the system, which in turn would not let the system build pressure 5 cent o-ring $600 bill. they tried radiator, water pump, thermostat before they finally pin pointed the issue. So maybe a pressure check? Paul

 

Thanks! That would explain all the symptoms. A good idea and I do have a pressure tester. A word of warning from some prior posts. Jaguar recomends to not go above 14.5 psi when testing the cooling system.
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Well worth trying a pressure test.

However, I get heat even with the radiator cap loose (so, no pressure).

 

As I mentioned earlier check the connections on the auxilary and DCCV pump and the wiring harness is known to chafe where it slots thru a frame member down below. You will have to take off the front valance by taking off the engine valance first and then the front valance.

Check the connections on both ends of the harness.

This advice is worth exactly what ya paid for it...

 

An update. I think I have found the problem and it's the AUX coolant pump like I thought.

If you have no heat try this. Drive with the engine at 5K rpm with the heat on max. I got roasted by the heat!! Backed off on the rpm and the heat died.

Looks like the AUX pump part number is C2C6517. About $170. I wonder if the Lincoln LS part is the same? It sure looks like it from looking at my wife’s 2003 LS.
When I change the pump I will report back on what happened.
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I have same problem of no heat& replaced the dccv on my 2004 s-type. Where is aux coolant pump located?
Thin advance esipp

 

Well if you changed the DCCV you had your hand on the AUX pump. It's right in line with the DCCV. Now be careful because only the V-8's have this pump. The 6 cylinders do not.

Again no car information so I am guessing again.
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Hi, esipp.... Wow, another Akron neighbor! Probably a good idea to update your signature with at least your year, model, and engine. Others on here have more elaborate signatures...

About the heat... could also be air in the system from not bleeding it after changing the DCCV, as well as a thermostat, and what "clubairth1" said.

We really need more details...

 

The last post was from my iphone which doesn't allow for adding a signature - sorry about that .

 

Essentially, I have no heat in the 2004 S-type 3.0. The a/c blows cold both sides. I have replaced the dccv. I am going to replace the thermostat and have the coolant flushed and bled today. Hopefully, that works. Any advice short of replacing the module would be helpful :-)

 

Jeff are you from Akron/Surrounding area?

 

Do you feel heat in any of the pipes to from the DCCV?
The two pipes from the v/v to the heater element run up the right side inner wing and you can get a hand on the inlet pipe fairly easily.

 

yessir.... live in Forest Hill (that little triangle in North Hill)..

Yes, get it bled before you start to fret about the CCM... But may want to look at that as well.