[DaveN]

Here's an odd one that exists in my S2 and I am trying to compare it to my 968 for funtionality but can't quite reason out what is going on. In my S2 I have to turn the knob up to 27.5 to get heat on a 15 degree day, turn it down to 26 and the heat goes off even though it's still cold in the car. I have swapped the head unit out with my 968 and it functions the same. There is a new <acronym title='heater control valve'>HCV</acronym> and it operates via the "suck" method just fine.

I have watched the <acronym title='heater control valve'>HCV</acronym> and it doesn't appear to move whether the temp is low or high. Did the same thing on my perfectly operational 968 and the <acronym title='heater control valve'>HCV</acronym> never appears to move either <img src="/forum/images/smilies/968/wacko.png" class="smilie" alt="" />



Anyone hazard a guess as to what I might try to get the heater to start regulating at the correct temp?

Search just reveals a lot of no heat or full heat solutions.

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[tamathumper]

According to Clark's Garage, "A problem with the heater control valve opening may also be caused by the vacuum solenoid valve going bad. Remove the solenoid and apply 12 VDC to valve to see if it opens and closes properly."

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[banditsc]

The temp sensor in the car?

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[DaveN]

I would assume the temp sensor is in the head unit fed by the little breathing window and hose behind the dash. I have replaced the whole head unit with no change. It's just odd it's migrated to a higher number but functions properly. I'll chase the vacuum solenoid as the <acronym title='heater control valve'>HCV</acronym> operates just fine. Tks guys.

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[tamathumper]

Bad relay (type 53 from memory)? Swap it with one of the other type 53's?

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[kwikt]

Have you checked to see if the little fan at the end of the temp tube is actually working? In my case, I used compressed air to blow out the dust and lint that was lodged in the miniature fan. This actually fixed my temp control knob problem.

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[DaveN]

Cool, a litte fan? I thought it was just convection. Will check that out as well.

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[kwikt]

Trace and Pull the rubber tube off and you will see a very small electric turbine fan that sucks in the cabin air temp and is controlled by the panel climate control knob.Could be the tube isn't even attached. Very strange setup. After cleaning mine there is a very distinct temp click sound when the knob is changed to a different temp. It's worth a try and doesn't cost a thing.

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[DaveN]

WIll have a look. I know the tube is on as I have chased this before and made sure it was making contact when I reassembled it the last time after swapping the control head with my 968.

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