Heat Temp Adjustment Issue

[hazzac181]

Next on the list while I wait for seals to arrive to (hopefully) resolve my fluctuating idle issue with my M103: the heating system.

The issue is, unless I "click" the manual temperature adjustment dials into their max heat (all red position) I have cold air. Once "clicked", I have very hot air. At the dial's highest temperature before the click, I have only cold air.

Any leads on what to test/trace first? I can only assume this is vacuum related, however I have very limited understanding of the system.

Also, does anyone (pref. Melbourne area) have a functioning fan speed switch? Mine only activates the blower motor in positions 3 amd 4; 1 and 2 do not engage the heater.

Kind regards,
Harry

[John Green]

My guess would be that the dials have failed. They are a potentiometer from 0-99 and then last bit is a traditional off/on switch. So the potentiometer bit is broken, but the switch works. I read them two days ago and nearly posted the above theory, but then thought maybe not as what are the chances of both failing at once. But, this morning I realised that the same feed signal most likely goes to both switches, hence they both act the same.

I would see if you can "borrow" a control module to test the theory.