Heater intermittantly stops working.

[tmaxx]

I have a 2010 Ford Fusion Hybrid. I live in Indiana, so a heater is essentially during the winter months. A few days ago my heater stopped blowing heat. There was a very small amount of heat coming out of the vents even on max setting. I tried swapping out the heater blower relay with the rear defroster relay in the engine compartment relay box. When I swapped the relays, the heater fan started working agan. I then swapped the relays back to the original configuration and the heater was still working so I wasn’t sure what to conclude. I drove the car for a few more days and the heater worked fine. This morning, I started my car for work and the heater turned on momentarily and then nothing except for a very small amount of heat on max setting. I started off to work and about half way into my drive (20minutes), the heater came on full and worked for the remaining drive. So it seems the heater fan is intermittently working. Any ideas on how I could troubleshoot this or what I should look at replacing? It’s going to get very cold here in Indiana soon, so I don’t want to end up losing heat again! Thanks.

[lolder]

I believe the heater won't blow air in "Auto" climate control until the ICE has warmed up enough to heat the heater core. Taking the system out of "Auto" improves nothing in either heating or AC mode. When you start pushing buttons, the system can get confused for a while. Leave it in "Auto" with the temperature set where you want it and see what happens. On cold days it may take several minutes for the heat to start.

[tmaxx]

I believe the heater won't blow air in "Auto" climate control until the ICE has warmed up enough to heat the heater core. Taking the system out of "Auto" improves nothing in either heating or AC mode. When you start pushing buttons, the system can get confused for a while. Leave it in "Auto" with the temperature set where you want it and see what happens. On cold days it may take several minutes for the heat to start.

 

I never use "Auto" feature. I just adjust the dial to max temperature since it's been so freezing cold here.

[srogers]

Have the coolant levels been checked? If it is low the heater core may be empty.