On a 94 Explorer, with the fan speed control **** set on its highest setting, should there be a further increase in fan rpm when the other control **** is moved into the "max" position from one of the other positions? Please only respond if you know for sure. You guessed it, my fan turns the same speed as when the unit is not on "max". Thanks.

 

Max means that it recirculates the (cold) air in the vehicle making it colder and colder as opposed to using outside air. It is more "efficient", the only drawback is you cannot use the hot/cold blend **** with max ac, of course why would you want to..

 

So there is no RPM boost for the blower motor like on my Suburban?

The reason for my question is it seems like the fan is going slower than it did five years ago ( I know I am). I do get a speed change at each incremental fan speed setting, so maybe its my imagination. I took out the resistors from near the firewall and they looked ok. I peaked in the resistor hole and the visible side of the accumulator looked clean, although I vacuumed out a small amount of debris.

Could the fan just be going slower, but still have all its speeds?

 

Possible I guess, were basically at the limits of my knowledege on this topic. I do know for sure that max means "recirculate".

 

When the air reciculates, the fan will sound like it's going faster, because there is less air resistance and the airflow will increase. Thus the fan may sound like it's going faster (and may be going a little faster) but it's because of the reduced airflow resistance, not a different votage to the fan motor. That being said, sometimes the door will hang up and it will not truly recirculate on some of the older Explorers. I noticed on my '92 the other day it hung up for about 5 minutes until I hit a bump in the road. This can be because of a vacuum leak or just plain old sticking in a 10 to 15 year old car.

 

True, max is "louder".

 

The blower pulls air from two places, in normal mode it pulls 80% outside air from the cowl below the windshield and 20% from inside the cabin, when in "max" a door opens on the inside to increase in inside air intake to 80% and only 20% from outside. The recirculate door is on the passenger side behind the dash, when in Max you hear the air intake which sounds like an increase of blower speed.

 

Thanks. Since I get no change in sound, your advice seems to be to check the blower diverter door. I'll do that next time my son comes home from school. I guess there are some good posts out there on the blower door problem.

 

From earlier in this thread - the motor itself has no speeds. It just runs faster with the more votage it gets. The switch on the dash runs through resistors that reduce down resistance, increas voltage, with each click - down in this case since that's how the switch is positioned on early Explorers. If you still have the owners manual, it tells you about the MAX AC recirculating the air inside the cabin.

 

Note that many of the "Blend Door Fix" posts refer to a different issue with 2nd Generation Explorers. Your's is a 1st Generation, and the door works differently. The most likely problem is either a vacuum leak, the vacuum actuator on the door has a problem, or the door is sticking.

 

max A/C just closes the vent.

 

Wow, I always wondered about this too!
What a great site this is!

 

Thanks All. Great help.

Someone mentioned the resistors that reduce the fan speed. This I do know something about. They are on the inside of a little "hatch panel" on the side of the evaporator chamber under the hood, near the passenger firewall. If your fan stops working at a low speed, but still works at high speed, these are your culprits. Very easy fix. The hatch also gives you a peek at the evaporator. You can clean out any debris with a vacuum and a fexible hose.

 

Yeah Craig - that was me. I have not had to either find or clean these but thanks for the advice. I only knew of this since that is how a basic reostat works and that is also what is shown on the vehicle schematic.

 

Yes....it just recirculates...BUT.....

That will generally provide COOLER air (I'm figuring) thus, the justfication for "Max" - I assume. Why? I reason that the system only has to cool air that has already been cooled. When pulling from the outside, it has to cool the air from whatever the outside temp is down - continuously.