Too much heat!

Greetings all great early 911 Knowledgebase,

The other day I decided to use the heater in my newly-purchased '73 S coupe, and was thoroughly impressed with the amount and temperature of heat produced by heat exchangers. I was less impressed when I couldn't get the heat to stop and it all but melted my left shoe!

Basically, the entire system works extremely well...I just can't get hot air from seeping out of the vent above the driver's left foot. My first thought, simply based upon my readings, was the flapper just after the heat exchangers...but I'm hoping to hear that it's less complicated than that.

Thanks in advance for any help you can provide.

Tony

Tony,
It sounds like the left heater control valve (under the car at rear) needs to be adjusted. The interior lever controls a cable that mechanically opens and closes the heater valve. With the valve "closed" (no interior heat), all heat from the left heat exchanger should be diverted to atmosphere.

Try spraying the offending cables and heater valve pivot with WD40 or Kroil and see if this frees up the range of motion. If this doesn't work, loosen the cable adjustment and verify the valve can open/close; lube it if necessary, then adjust the cable.

Hope this helps,
Early 911S Registry web

You nailed it, the driver's side heater control valve was indeed the problem. During my troubleshooting, I noticed that the large air control valve - accessible from the "trunk" - on the same side of the vehicle is cracked and needs replacement. And let me tell you...I'm really looking forward to re-adjusting all of the control linkages! <sarcasm>

Thanks for the help!

Very best,
Tony