The most common issue is the heater / climate control valve. This can usually be tested in dual mode and checking for change in air circulation.
Where is the heater control valve on a 1994 Buick Regal
were heater control valve for 1996 buick park avenue
How to fix heater in Buick there is cool air ,fan is work .but no warm air
To fix the heater in a 1992 Buick LeSabre, start by checking the coolant level in the radiator and reservoir, as low coolant can cause heating issues. Inspect the heater core for leaks or blockages and ensure that the heater control valve is functioning properly. Additionally, check the thermostat and replace it if it’s stuck open. If the problem persists, consider examining the climate control system and the blower motor for any electrical issues or malfunctions.
Thermostat stuck open or heater core clogged. Bad radiator cap or small hole in cooling system.
possibly when the a/c is not needed to cool the air temperature you set. The A/C control module has failed, as revealed on a diagnostics check.
take one end of your heater hose off the heater core and run it back to the intake port.
There is a fellow on Ebay that repairs these controls. It is easy to remove from the car and he will repair your control and ship it back out in 24 hours. He repaired mine 15 months ago and it still works perfectly. His eBay username is "musclos1" The title on his current ad is "1998- 2000 Buick Regal Century Climate, Heater Control" His current price is 36.95 including shipping.
To reset the climate control on a 1994 Buick Roadmaster, start by turning off the ignition and disconnecting the vehicle's battery for about 10 minutes. This will reset the climate control module. After reconnecting the battery, turn the ignition back on, and the climate control system should be reset. If issues persist, consult the owner's manual or a professional for further troubleshooting.
If the sensor is blocked or has mud on it, the readings will be inaccurate, and give completely false readings.
may be your heater control valve
Low freon