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[Kevin Wood]

Yep, pump is driven from climate panel directly. No relay, on the facelift, at any rate.

The pump not running wouldn't result in the heater not working. I can't remember if it even runs at all except when using the "residual heat" when parked up. IIRC, it runs constantly when not configured on the climate panel, too.

Sounds to me like the heater matrix or HBV is blocked, especially if you had no water in the loop around the winter pack pump. I know you've checked these, but what about vacuum feed to the HBV?

I think the matrix can block but still allow water to circulate around it, if that makes sense?

[allen25]

I can see that you are getting some very experienced attention to your post. I had the same issue with no heat in the cab but could be for a completely different reason. I took my V6 off the road for a while whilst finding time to replace the oil cooler. The coolant system was clogged with 'goo' as you might expect. After O/C replacement I had no heat in the cab and I was expecting to have to change the HBV (not unusual and I know you've changed HBV). I chose to flush/run the system for a good many miles with detergent, regularly draining and refilling. I used non-bio washing powder (many on here have used different flushing agents). I did 'rod' some of the coolant pipes too whilst the engine was stripped down. The heating did come back to life and no HBV change (lucky for me). No doubt you'll sort it. I did this in the summer with no freezing risk!

[robson]

I was about to ask about the pump in the heater circuit when I saw this post. I assume that the pump is the one on the left hand side of the engine bay looking from the front. My car temp indicator takes  a long time to warm up but I notice that the heater pipes get hot even with no heater switched on should the pump be idle with the heater switched off and therefore no heat in the pipes Can any experts describe the action of this system.

[TheBoy]

Just do a test, pop the vac pipe off the top of the HBV. Does it heat up then?

[m.ian]

Have removed vac pipe from HBV and no difference 

Still only get hot air in cabin when engine is revved above 2000rpm

Winter pump has NO power to it (only 0.3v)?

I am will now to pay somebody to get this sorted.

Any takers???
PLEASE

[TheBoy]

As a quick test (wondering if pump is blocked), can you get a suitable sized elbow, and plumb it in in place of the pump?

I can't help but feel the pump is a red herring TBH...

...looking at wiring diagrams now.

[TheBoy]

As Kevin Wood says, directly powered from ECU.

[m.ian]

Ok thanks
Looks I need to get some Tech2 help?
Anybody close to me?

[TheBoy]

Think Marks DTM is closest to you, if he's got any time.

[m.ian]

OK will PM him and hope that he can help especially as it is getting colder

[m.ian]

Update.
Remove Vac pipe from the HBV and there is no vacuum either with heater on or off?
Any ideas?

[Kevin Wood]

No vacuum means the heater is enabled, so you should have heat. I think it only blocks the feed to the HBV when the climate panel is set to "LO" for maximum cooling.

Is the pipework to the pump and back getting hot?

My money is on a blockage in the system somewhere, so should be resolvable without a Tech 2, IMHO.

[m.ian]

Ok understood and I will check for vacuum with heater on LO to check.
Yes pipes get hot but they are not full of water and when return pipe from heater removed very slow flow of water from the pump when engine running.
As stated before have flushed matrix and replaced HBV but not getting any heat in cabin unless engine revved above 2500-3000rpm.
Any suggestion on where to look for the blockage would be great!

[allen25]

You may have done it, but it could be worth trying the bypass suggestion to start ruling thing out?

[Kevin Wood]

If you remove the aux. pump you can see into the ports to the impeller housing. You could check it visually for any leaks, I'd have thought. At the same time, you could exchange it for a 90 degree elbow to see if that improves matters.