I have a 2003 Grand Caravan Sport with 3.3l. Since last winter the heater stopped blowing except on the hi fan speed, and no heat. I replaced the blower resister and the fan is now working on all speeds, but no heat.

I checked the hoses going through the firewall, and the top one is cold, but the bottom one is pretty warm. Not too warm to hold onto, but very warm.

Do I need an "air blend door actuator"?

Any other troubleshooting tips? Thanks.