it is a heater. heat. it blows heat. warm air
its happen because heater core have too much durt insaide and you can clean it with some blowing thing or replace
Because you don't have enough coolant in your radiator.
You should check the thermostat and the fuse for the heater.
Most likely a replacement heater core
Assuming the heater works fine, you have a short, probably in the AC compressor clutch.
you need a new thermostat and possibly some anitfreeze
Check the wiring on the starter. Also check all grounds
check the coolant level, or, possible stuck thermostat.
It could be the heater valve which is located under the hood to the passenger side down below the radiator and fan units.
If the heater in your 2000 Volvo S40 is blowing cold air, it could be due to low coolant levels, a malfunctioning thermostat, or a clogged heater core. Low coolant can prevent the heater core from receiving enough hot fluid to generate warmth. A stuck thermostat may not allow the engine to reach its operating temperature, resulting in cold air. Finally, a clogged heater core can restrict airflow and heat transfer, causing the heater to blow cold.
One of the reasons a 2000 Jeep Cherokee heater would randomly blow cold air and then hot air and then cold might be that there is a problem with the hot/cold duct. The air or a vent might be inadvertently blowing periodically.
is a slow running fan heater going to give same heat as a fast fan heater if both 2000 running at