Thanks for the Interest,
The problem is not when I am on the highway but when the car is in the driveway and it is cold out and I want to defrost the window before I go anywhere the heat will not come into the heater core to warm the car or defrost the window until I drive down the road and bring up the rpms to overcome the fact that the booster pump located in the engine compartment on the firewall above the engine does not run, I pulled it out and tested it was OK but is not powered when idleing as it should, that is why I am thinking that there is a sending unit somewhere that tells this pump to turn on initially to get heat fast to the heater core then turns off when you are going down the road as if it did not the motor wouls surely wear out after a long trip being a brush type DC motor, I hope this makes snse to you, Thanks, Don