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[JamesV6CDX]

Changed my HBV today, hasn't made a difference though.

Here are my symptoms:

I ONLY get heat into the cabin, when I remove the vacc pipe from the top of the HBV. If you remove the HBV vac pipe, there is plenty of heat.

As soon as you pop the Vacc pipe back onto the HBV, it takes all the heat out of the cabin.

With the vacc pipe off.. the temp reduces a fair amount when it's set to LO, but still fairly warm through the vents.

Question is - why can't I get any heat into the car, when the Vacc pipe is on the HBV?

I don't think it's a problem with the vacc pipe configuration, because Mark gave them all the once over not long ago, and I've not altered anything since.

I'd really appreciate any advice, bit stuck on this one and it's driving me totally mad.

Cheers
J

[sounds2k]

seeing as I've not had the dubious pleasure of replacing a HBV (as yet), what are all the connections to and from the HBV?

I expect to see:

main coolant in & out
heater matrix in (possibly out or maybe that connects to one of the other coolant hoses)
vac feed
... and possibly some sort of electrical connection?

there must be some sort of switching, so if there is no electrical connection to the HBV then the vacuum must be switched instead, somewhere between the HBV and the main vacuum feed off the servo - in which case I'd be looking there ...

[TheBoy]

With the current high temps, and your a/c not working, it will not blow cold. However, see my reply in your other thread.

[Jay w]

the HBV has three water pipes attached to it and a vac hose, this controls the heat/cold.

Having had issues with my miggy when i first got it i found that the HBV is controlled by a vac unit inside the car, when you select a cold temp it creates a vacumn and so i would imagine causes the diaphram to open/close and so control the flow of water into the heater matrix.

Have you looked at the controls by the heater box in the car James, IIRC the one for the heater control is on the passenger side and is the one nearest the bulkhead, they are a PITA to get to and do anything with.
All i did with mine was to suck it an see, literally, suck on the end of the pipe gently and see what happened, hot/cold up/down ect

HTH

[Matchless]

Have you synchronised the servos? Auto & Off for few seconds, then you should hear the servos cycling round.

Otherwise sounds like a vacuum pipe disconnected on the cabin side of the bulkhead grommit

[Kevin Wood]

What about the solenoid valve that controls the vacuum to the HBV? Could this have failed causing continuous vacuum to the HBV and therefore no heat?

May be worth locating this and see if it clicks when you apply 12v. May well be able to deduce if it's working by sucking and blowing on it at the same time.

Kevin

[TheBoy]

Reason I said check the sampling fan, is I had exactly same issue. In my case, it was where I had temp rigged up a new phone mount on vent mount, and it covered the sampling fan....