HVAC fan speed is weak

[Guest Stormbringerut]

Morning guys. My 1988 has always had weak HVAC fan speed. I can hear the motor running on high but I do not get out nearly as much speed/pressure out of the vents. The defrost does come out plenty fast. Any ideas? Does the HVAC system have a filter that might be plugged some? The vents do work just at high speed they are comparable to my other vehicles at low.

Mike.

[Guest Mc_Reatta]

There have been articles here in the past about cleaning the front of the evaporator by going thru the blower control module opening or the blower fan opening with an array of brushes and home made vacuum cleaner wand modifications. Lots of debris can build up in there over the years.

Would seem this would also affect defrost mode also, so you may have a weak vacuum operated flapper valve that doesn't close off the other air channels and diverts all the air out of the dash vents.

Do you feel air flow from the other vents when you are configured to send the air out of the dash vents?

It's hard to get at that valve, but by switching between all the delivery modes, you might be able to exercise that valve and get it to work more freely.

[Barney Eaton]

I posted some photos of a coil with crap covering most of the front 2-3 week ago but cannot find it. I suspect you have the same problem.