A few weeks ago I flushed out my heater core to my '98 Grand Cherokee (a lot of crap came out, and I thought that was it). This seemed to help the problem with my heat not blowing through the defrost, or vents. But It didn't fix the problem. I tried it the other day, still cold! When I don't use the blower, the heat seems to build up enough to blow hot for a few seconds when I turn on the blower fan. But goes right back to cold in no time. I checked the two heater core hoses to see if they were hot. They are, so flow is not the problem. I seem to remember something about the heater doors not working correctly or a vacuum not doing it's job. Anyone able to help me out here?
Thanks'
M