heater controls stopped working after heater valve replaced

[philipdart]

Hi, I've finally got around to replacing the heater valve, which went OK. But in getting system back up to temp after the coolant refill, the hot/cold dial worked for a while, then stopped working and now stays hot (but never really went fully cool anyway (hence why I replaced the valve), then the directional dial stopped working as well, but a while after the temp dial stopped. Sounds like it could be the vacuum system more generally - any ideas please? Does the vacuum reservoir tend to fail? Thinking I may have overloaded the vacuum system with the new heater valve? Would be grateful for your thoughts please...

[Fredjohn]

Firstly make sure you have correctly attached the operating link/vacuum tube to the valve, or it hasn't come off.
Secondly look at the workshop manual for your heating system: 4 or 6 position as appropriate.

I suspect a pipe has become detached from either the control knobs or perhaps from the reservoir. It doesn't usually fail. Remove the nearside (UK) wheel arch liner and you will see the reservoir. Should be 2 pipes attached. One from the inlet manifold the other into the interior to a control knob. Check all these connections.

It is fiddly and inaccessible. You may need to remove the radio for easier access. So good luck in tracking it down. The WSM gives a very good schematic of the vacuum system which should be of great help.

[philipdart]

Firstly make sure you have correctly attached the operating link/vacuum tube to the valve, or it hasn't come off.
Secondly look at the workshop manual for your heating system: 4 or 6 position as appropriate.

I suspect a pipe has become detached from either the control knobs or perhaps from the reservoir. It doesn't usually fail. Remove the nearside (UK) wheel arch liner and you will see the reservoir. Should be 2 pipes attached. One from the inlet manifold the other into the interior to a control knob. Check all these connections.

It is fiddly and inaccessible. You may need to remove the radio for easier access. So good luck in tracking it down. The WSM gives a very good schematic of the vacuum system which should be of great help.

Cool, thank you! Didn't think I'd disturbed any piping when I replaced the coolant, but when I tested the old heater valve after I'd taken it out, it wasn't fully sealing shut so I guess the new valve could well have forced a pipe off somewhere else in the system. Will take a look!

[robertverhey]

I achieved reasonable visual access by taking out the glove box lid (right hand drive like UK) and using a torch, enough to see that the micro switch wasn’t being fully engaged when I turned the knob. A bit of minor fettling got it working again.

[philipdart]

I achieved reasonable visual access by taking out the glove box lid (right hand drive like UK) and using a torch, enough to see that the micro switch wasn’t being fully engaged when I turned the knob. A bit of minor fettling got it working again.

Thanks, have been in through there and the hot / cold rod had come away from the mechanism that opens and closes the microswitch. So that's fixed the hot / cold but not the fact that I can't now change the air distribution between screen, face and footwell vents. All the pipes are connected on the back of the dial and I can't see anything else that's off.

[Simon_P]

Have you checked all of the connections in the engine bay? Including the ones unrelated to the ventilation system?

[philipdart]

Have you checked all of the connections in the engine bay? Including the ones unrelated to the ventilation system?

I seem to have found the problem - one of the vacuum pipes from the reservoir was attached to a nipple off the side of the plenum that I wasn't convinced was the right place for it. Moved it to a nipple with a rubber outlet at the top - back of the plenum and it now seems to be working. Think it was wrongly attached to the EECS feed.