So, a few years ago i changed out the heater core in my 1993 civic. I put it all back together but was never able to get the hot/cold lever to slide just right. It always felt like it was binding before reaching either end of the slider. Everything works (AC doesnt work anymore, long leaked out) though. I continued to drive as is but always felt like there was always a "little more" heat coming out of the vents than i remember in the cold position. Can someone give me the procedure for adjusting this thing again? Which side of car will i be working under the dash? Thanks.

 

I tend to think the cable that goes from the bottom of the heater core flapper box through the firewall to the coolant valve for the heater core in the engine bay might be a bit off.

If I recall on the 92-95 series, that cable has a hold down on the bottom of the flapper box. If the cable moved or is out of the sweet spot and locked down, it would affect the valve position in the engine bay. As well I think it can adversely affect the flappers in the box itself. I can't remember if the white slider arms are connected together. If they are, the restricted motion of the one would affect the other just compounding the problem.

 

I am sure you are correct. Is there a write up or procedure to adjust all this?