Many HVAC systems operate with vacuum supplied from the engine. If the vacuum supply is cut off the system goes into default position which is floor and defrost. Look under the hood for a small vacuum line from the engine leading into the firewall that is damaged, cracked, pinched or disconnected.
Could be a vacuum problem--either broken or disconnected hose or bad vacuum motor under dash or coming in through firewall Defrost is the default position for this system
ihave a 1986 chevette that when i turn defrost on it blows out heat and when i put heater on it blows out only cold air? ihave a 1986 chevette that when i turn defrost on it blows out heat and when i put heater on it blows out only cold air?
You have vacuum line leaks somewhere.
You either have a bad controller or a bad actuator.........
The 1984 Buick uses vacuum lines to change air flow from defroster to ac vents. Check the entire vacuum system for leaks.
Because your battery terminals are rusty. Have your dad clean them, and then check it again.
Central Air Conditioners are installed into your house to provide cooling air in every room using a duct system. They are very refreshing on a hot day.
blower motor resistor
An air conditioner blows out heat
Check under the hood for a broken or disconnected vacuum line.
Most likely a bad or disconnected vacuum hose to the defrost/floor selector in the heater ducting.
Most of the ones that I have seen have dirty condensor coils. That's the coil you see from the outside. They get dirty on the inside of the air conditioner where the fan blows air through it.