Blue's_Z28

iTrader: (2)

I experienced an odd problem yesterday regarding my a/c blower motor. I was on a road trip and after about an hour my blower motor volume degraded to a small fraction of what it is supposed to blow. Even on the 4th speed setting the volume of air coming out of the vents was very small. The air was definitely cold but the amound of air coming out was only a small fraction of what it's supposed to be.

Got to my destination, had lunch with the family, and 2 hours later I'm back on the road the a/c blowing like normal. Again, after about an hour, the volume greatly decreased. Turning off the a/c had no affect while driving, it only returned to normal after the car sat for a couple of hours.

Blow motor regulator? Thoughts?

Thanks in advance!

fleetmgr

Take a look at all vacuum lines - especially where it comes of the back of intake. This sounds like the heater box doors are slowly going to some intermediate position rather than being fully one way or the other. My 95 S-10 does the same thing, but cycling the control valve on the dash puts things back to where they are supposed to be. By control valve I mean the **** that selects heat, vent, A/C etc. All it does is port vacuum.

wssix99

iTrader: (5)

+1 You'll have the same power coming from the motor. The question is more about where that power is being distributed.

For example, if you have the **** set for the forward vents only and you detect weakness - check the other vents and see if air is coming out. If so, you'll be able to trace the vacuum system issue to the diverter that controls those other vents.

2001NBMZ28

If the temp diminishes a little at the same time might be the evaporator freezing up.

MikeG

iTrader: (33)

Another vote for freezing up. Make sure your freon level is right.

fleetmgr

The only way the evaporator could be freezing up with the symptoms he describes is if the air box drain line was plugged. If it built up enough water in the air box to freeze up to the degree that it impacts air flow, it would be all over the inside of the car.

Blue's_Z28

iTrader: (2)

Yeah I don't think it's the evap. Let me clearify: the RPM of the B.M. is what drops off. Even at the 4th speed selection the B.M sounds like it's at the 2nd setting. Temp of the lower volume of air is still cold, I don't feel a temp drop off at all.

Thanks for all of the replies so far. Right now I'm leaning towards a B.M. regulator and/or pushbutton/switch assembly.