We’ve got our 64 Dodge 880’s heater core out to take to our radiator guy, becuase it appears to have a small leak. We’re trying to solve the problem of not enough hot air in the cabin. The main radiator has been checked, cleaned, and flows well. The engine comes up to 180 degrees nicely, per the thermostat. And all the vacuum-powered duct actuators and doors are working properly. (That took some doing a few months back.) We were wondering whether the heater control valve might have a blockage, so we took it out to check. Can someone explain the theory of operation of the control valve? It’s not just a simple valve. The factory manual is sorely lacking in heater system information. There is some sort of thermostat function as part of the control valve assembly. A copper coil inside the heater duct leads to a little piston that appears to bias how much the main valve opens. There is an adjusting screw which can be adjusted to remove slack. The question, of course, is what position should it be adjusted to at ambient temperature (say, standard temp of 59F). Or perhaps there is supposed to be slack before the control arm starts opening the main valve (?). Looking forward to learning more about this heater functionality. Dan Davids Seattle -- -- -- Please address private email -- email of interest to only one person -- directly to that person. That is, email your parts/car transactions and negotiations, as well as other personal messages, only to the intended recipient. Do not just press "reply" and send your email to everyone using the general '62-'65 Clubhouse public email address. This practice will protect your privacy, reduce the total volume of mail and fine-tune the content signal to Mopar topic. Thanks! 1962 to 1965 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html and http://www.1962to1965mopar.ornocar.com/general_disclaimer.html. -- You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group. http://groups.google.com/group/1962to1965mopars?hl=en. --- You received this message because you are subscribed to the Google Groups "The 1962 to 1965 Mopar Mail List Clubhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to 1962to1965mopars+unsubscribe@xxxxxxxxxxxxxxxx. For more options, visit https://groups.google.com/d/optout.