Over the last couple of weeks I have noticed a couple of instances where the air coming out of my vents seems extremly restricted.  There is a little bit of air coming through is not normal.  As I move the fan speed switch I can here the blower motor speed up and slow down accordingly. The vent selection makes no difference as it will vent air where Ihave it selected.  Cold or Hot, no difference there either.  It didn't work all weekend, but when I got in this morning the air blew very strong??  I assume that the problem will come back.  It has been cold and wet here, but nothing record breaking.  Could this be a symptom of a bad blend door?

 

Any feedback would be much appreciated.

I would think it would be the resistor. Either that or you have some sort of physical blockage in the system.

Actually this is a sign of plugged up evaporator core.

 

 

As you can see no matter what the air must flow through the evaporator first before the blend door which is just to the firewall side of the heater core.

Does the air come out of the defrost openings at the same time the vents are selected? If so then you need to look for a vacuum leak (which is more common than the evap plugging AND a whole lot simpler),  BUT thee is always that possibility of a plugged evap.

This is kind of a long shot.... Did you have someone riding with you over the weekend? One time, I had a very tall buddy with me and he was trying to find more room. He ended up shoving his feet up under the blower motor and must have pushed on it just right because it stopped working. Thought my motor went bad. As soon as he got out it started working again.

If you have blower running & varying speeds...  then the motor & resistor are good.  I would suggest dropping the motor in the passenger's foot well.  I have found a mouse nest in the "bird cage" blower wheel...  I've also found mouse fluff clogging the evap.  If you find mouse sign...  you should clean the resistor housing where it sticks into the air flow of the heater duct...  mouse fluff will hold the heat in & cause the resistor to fail from over heating.  It's annoying to get the heater back but only 3 screws. You'll know a lot more after this basic investigation.

If mice are getting in, use SS steel wool (pot scrubber) & shove up under/behind the hood hinges where the cowel drain is.  The water can still drain but the mice can't get through.

 

It could be a blend door issue but lets find out if there's a clog first.