Hello, I am having problems with the heater on my 240 Z. The hot and cold valve functions correctly, but the TEMP slider only reaches halfway through its range when attached to the valve lever. The valve lever does move through its full range when attached to the cable.

Edited September 2Sep 2 by keijz

I don't like the look of the bends (kinks) in the hot-cold control cable at the end where it ties into the inside end of the control lever. That typically indicates that the water control valve is (or was) partly seized. The cable bends when the driver (or passenger) pushes too hard on the outside end of the control lever in an attempt to get more heat. Once the control cable deforms, it tends to bow out whenever it encounters too much resistance. When it bows out, the fore-aft motion of the cable becomes compromised.

You will never be able to restore the shape integrity of the control cable by trying the straighten out the bends. I recommend that you replace it. If you can't find an OE replacement, you can make one using tempered steel wire (aka 'piano wire'). The step at the end that fits into the control lever can be easily formed in a bench vise. Early Z's (until ~ July 1972) used 1.0mm wire, with straight-end finishes that were secured with pinch screws. After that, the system was redesigned with 1.2mm wire and looped ends that fit over pegs. I suspect that your car's system uses the 1.0mm wire.

Make sure that your water control valve is free over its full design range-of-motion (I suspect that it isn't). Try soaking the control valve in a household de-liming chemical (e.g. 'C-L-R') for 2 or 3 days. A more reliable strategy will be replacing the valve with a new one ($$$).

Thanks, Namerow, for your help.

I will take a close look at the potential problems, you mentioned, and order new parts, if necessary.

Regards, Piet.

Quick test is to disconnect the cable from the heater valve and see if the temp control can move through its full motion. This will prove the valve is faulty and lets you see the distance the cable core moves at the valve to let you understand how far the valve arm has to move.

Another issue might be a sync issue. You have to position the valve in full open position by hand first, then position the temp control lever in the full hot position, THEN tighten the set screw on the core at the valve. (Can also do this in closed/cold position). If the lever was half way when the valve was fully open or closed, then the lever movement would be restricted to less than full motion

I understand. Thanks zKars.