Sounds like a stuck thermostat to me. Air or another obstruction in the heater core would lead the hoses to be dramatically different temperatures, and air would likely work its way out of the heater core.cthomasparr wrote:I survived the winter with interior heat only about 2500 rpm or over. Would blow cold air at idle. I suspected a clogged heater core but noticed that both heater core hoses by the firewall seemed to be at the same warm temperature. I was hoping to do a reverse flush but I wonder if I might have another problem. In the event where I may do the flush which hose flows into and out of the heater core?
I remember at some point one member here was able to purge a stubborn air pocket out of the heater core by reversing the heater core hoses, where they connect at the firewall. They are the same diameter, and the core doesn't really care which is in or out.cthomasparr wrote:I survived the winter with interior heat only about 2500 rpm or over. Would blow cold air at idle. I suspected a clogged heater core but noticed that both heater core hoses by the firewall seemed to be at the same warm temperature. I was hoping to do a reverse flush but I wonder if I might have another problem. In the event where I may do the flush which hose flows into and out of the heater core?
On the Vibe, at least the 03-08's, the temperature control pushes/pulls a mechanical wire cable that actuates a flapper door. There was a common issue in the early ones where the cable wasn't adjusted properly, and setting the temp control to the cold left the door still partially open, resulting in warmer AC than desired viewtopic.php?t=1004 Unless that cable was disconnected, I don't think it is likely to cause a problem with low heatChiadog wrote: I had the identical problem on my 05 Chev Uplander mini-van. After much flushing, etc. the problem turned out to be electronic control module which the climate control knobs attach to. A crude test for this is to turn ignition on, engine off, in a very quiet place and see if you can hear the temperature flapper door actuate when you quickly spin the temp control knob from cold to hot and vise-versa, pausing to listen each time. I have another test if you need it.