I am having air flow problems as well as loss of heat. The blower seems to work well on vent and provides good flow of air but when you put on heat you lose air flow by 50%. When on heat you get short spans of heat (30 seconds) and then blows cold.

We also noticed in the summer that you would lose air flow after 30-40 minutes of AC operation. If you turn the AC off for 10 minutes you would have good cold flow for another 20-30 minutes. Is the condensor freezing over and thawing while the AC is off and if so is this caused by a low charge? Are the heat and AC flow problems related?