1970 Deville A/C Help / Advise Please

[Tim120]

Need some help on understanding my 1970 Deville A/C ( Climate control ). I notice that when I place the control level to "normal" ( vs low or high ), the a/c blows at one speed only. However, if I set the temperature higher ( say 72-75 degrees for fall / spring ) the warmer air will automatically vary with more or less force to maintain the proper temp. in the "normal" setting. My point here, when I have the temperature set say at 65 in the summer, the blower does not seem to vary within the setting of Low, Normal or High. It will blow on HIGH when set to HIGH, but there is no variation when set at "Low or Normal". Make sense? Is my issue "normal"? If not normal, what component in the a/c controls this and well, how expensive would it be to fix? Thanks in advance for the help.

[bill henry]

my guess is that the temp never gets down to 65 in the car, turn the dail up in summer and see what happens

["Cadillac Kid" Greg Surfas 15364]

Tim,
What Bill says is true.  The system will go to "high" fan speed when the temperature dial setting is far (10 to 15 degrees) from what the actual temperature in the car is.  If the system modulates the fan speed during heating mode then, unless someone has modified the wiring or the cooling side of the programmer's circuits, it seems as though the temperature control system is functional.
Yos said that the fan seems to be at a constant speed regardless of the position of control lever (i.e. Low, Auto, High).  If in fact this is true it seems that said modification (of some sort) has been done for who knows what reason.
Your particular system (1970) is a transitional one and the best suggestion would be to follow the factory shop manual in as far as the system's reactions (outputs) to the control settings.  There are several matrixs in your manual which should give you enough information to narrow your analysis down quite a bit.
But, going back to what Bill said, the system, if working precisely as designed will not be able to attain a 65 degree cabin temperature in hot and humid conditions.
Greg