2001 Chevy Astro not blowing hot

Hi kcfchi. Welcome to the forum. Do you have a temperature gauge on the dash? If so, is it reading in the normal range or is it lower than normal? If it's low, suspect the thermostat.

If the gauge reads normal, or if you don't have one, feel the upper radiator hose after the engine has been running for ten to twenty minutes. It should be too hot to hold onto for very long. If not, again, suspect the thermostat. Next, feel the heater hoses. They should be just as hot. If only the heater hoses are cool, suspect as plugged heater core. They can often be flushed out with a garden hose.

If the heater hoses are hot but you're still getting cool air, there is a problem with the controller in the van or with the temperature door actuator.

Caradiodoc

Do you have electronic controls or mechanical slide levers? If you have levers, you can follow the cable to the door to see why it isn't moving. Can I assume the heater hoses are hot? If they are not, moving the temperature control door won't help.

Caradiodoc

It is more likely there is a problem with the HVAC computer controller. If you look under the dash you might be able to see some of the motorized actuators. (They could be electric or vacuum motors). You might be able to disconnect their linkages and move the door manually to see what changes. You can also try disconnecting the battery for a couple of minutes to see if that resets the computer. That is always one of the suggestions for solving a locked up computer but it doesn't actually solve the problem very often.

Caradiodoc