Carrier weather maker 9200
 

Having a problem keeping the heater on. light blinks showing a vent problem. checked the vent and it was ok. unplugged the elec. and to let it reset which I had to do several times and it would come on and heat but not for long but some times days and then it would shut down and blink a vent problem again. Can someone give me an idea on what to check next? this unit has been in the same house for 10 years. Thanks

It could be a heat exchanger issue. Call a pro.

for sure call in a pro on this one as mentioned it could have a cracked heat exchanger...don't take a chance...:yes:

I would check that all the pressure lines are in good shape, no split ends or holes.
Make sure none of them are filled with water.
Make sure that there isn't a build up of crud just inside the vent motor assy where the pressure line attaches to it. Try a staightened paper clip to test or clear it out.
Make sure that the electrical connections are secure on all the pressure switches.
In addition to a possible exchanger failure, other common causes could be a failing vent motor, pressure switch or a partial vent line obstruction.
Let us know what you find.