Ryan, it could be your switch in the dash.  I have had them be flakey.
Sometimes, after sitting for a while, I just wiggle the switch around a bit
and it starts working on the other speeds.  Or you can buy a new switch and
try that.  Or you can take the switch apart, clean the contacts, and put it
back together.  Just sitting contacts can get just a bit more corroded.

The other part I have had lots of problems with is a relay that has the
number 13 on it that is located in the rear driver's side corner area of
the van (to the left of the rear hatch).  If this relay fails it will cause
all kinds of strange problems.  If your switch checks out, that would be
the next thing I would check.

Most likely it will be either of those.

Ken

On Tue, Feb 19, 2019 at 4:50 PM Ryan Cresawn <jrcresawn@gmail.com> wrote:

> My 1991 Vanagon Westfalia Camper has a 4-position fan speed selector for
> the air conditioner. The 2.1l engine is stock, but the air conditioner
> compressor was replaced years ago with one compatible with R-134a. In
> November I replaced the condenser and pulled a vacuum on the system for
> five days. Then I disconnected the A/C gauge set and vacuum pump. Last week
> I took my Vanagon to a local air conditioner repair shop. They charged the
> system and added oil. The air conditioner cools well, but I discovered on
> Monday before sunrise that my only working fan speed is 4. All four fan
> speeds worked prior to November of last year when I stopped using the air
> conditioner. Should I take it back to the shop to ask them about the fan
> speed selector or try to identify the cause of the problem and repair it?
> Any suggestions on where to begin the troubleshooting?
>
> Thanks,
> Ryan
>

--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com