69 CADDY DE VILLE CLIMATE CONTROL PROBLEM

[1969cadillac]

Hello - i have a 69 deville with a climate control problem

basically heat wont come thru the dash vents on the auto setting until the car has been driven for an hour - parked - then when you get into it again - it starts working

sounds like a sensor problem - i have replaced the one in the right kickpanel - but made no difference

system works ok otherwise - vent - ice - defog - work almost straight away ( dont have to wait nearly an hour for it to work!)

any ideas ?

murray mules

["Cadillac Kid" Greg Surfas 15364]

Murray,
First of all in a correctly function ATC (auutomatic Temperature Control) system, when the system is in heat mode, the air is intended to come out of the lower vents. If in fact the heat does finally come on, and if the AC is fully functional, I would suspect the delay might be caused by a leaking vacuum line or lines or connections.  I would check them first. Where in the world are you uusing heat now?
Greg Surfas

[cadillactim]

Murray

So the fan comes on in Vent and Ice with no delay?  Check for a bad ground in the Auto circuit.  Just behind the alternator is a sensor in the cylinder head with a single wire going to it.  Unplug that wire and ground it.  See if the fan comes on.  If so, you have a bad engine ground sensor, and possibly the dash sensor is bad also, as it completes the ground above 75 degrees.  Tim

[Steve W]

Greg is correct. Heat is not supposed to come out of the vents in the dash. Heat comes out of the floor level vents only. (Seems odd that heat DOES come out of the dash vents after an hour! Hmmm...)
There is a water control valve on one of the hoses that goes to the heater core in the fire wall. There are two or three vacuum lines that attach to the valve...one is a sort of timer. One of the other ones opens and closes the valve to control hot water going thru the system... make sure that valve is working. Also...you ARE running a thermostat, right?