940 hpt heater blower- later model with a/c cold until max?
 

I am really hoping this is not what i suspect.

The heaters have been so so since we got the car but my lovely lady has been testing them more as she likes to stay warm. She as noticed that the heaters blow cold until the top setting. The vents actually blow cold right up until near 26 and around the top settings (25 plus) it will be hot then cold as it settles.

The max max setting stays hot.

The car is a/c like our old 940 so could this be simply the temp switching system not working on the vents?

Or could this be the matrix ? No water loss however

Really hoping its not a big issue as the car has plenty of little bits to sort already and some bodywork.

Thanks
Mick

It would be worth checking the heater valve in the engine bay below the distributor is actually moving first, if it is an original steel one it might have rusted quite badly and not be moving properly.

It's more likely to be a dry joint on the valve block that operates the various functions by vacuum such as the heater valve, direction flaps within the hear box etc.

https://i.postimg.cc/TwJrz5vp/IMG_20..._114737103.jpg

https://i.postimg.cc/tTzV70TT/IMG_20...233945_HDR.jpg

https://i.postimg.cc/ydXvBYSr/IMG_20..._141536495.jpg

https://i.postimg.cc/rmCq5Wvy/IMG_20...641244_HDR.jpg

It could also be a lazy temperature sensor in the interior lamp.

Without the vacuum system being functional, the temperature can still be changed but it only has three gimped settings.

26° to the red mark will be full hot.

18° to 26° is the same 'medium' setting.

18° to the blue mark will be full cold.

With the ignition on 1 you can faintly hear a motor moving when you go past these thresholds.

I say gimped because the system defaults to the airflow being rather **** without the vac flaps operating. Stupid design. The old mechanical sliders on 740s were better.

Thank You for the help again guys. I am much happier with dry solder joints over matrix change :cool:

Ill lubricate the bulkhead unit over the weekend too

Wonder if there is any spare units around to repair before fitting

Even if there were, chances are they wouldn't be far behind so it's more cost-effective and also time-effective to pull the one you have and repair that then refit. At least then you know if you've got the fault. :thumbs_up: