It has been a while since I have written code for this type of thing. Back in the day, printer drivers only spooled a few file types, eg Raw and Prn. I can't remember all of the details but I believe it is a two step process. Convert the file to prn or acceptable file format and then spool it. I think what I did was use the printer driver to do the conversion to prn and then used the FileSystemObject's copy method to spool. Here is some code from one of my DB's.
Code:
' ' Use the copy file method to send RAW files to a printer device
'Print a RAW file
Dim FSO As FileSystemObject
Set FSO = New FileSystemObject
FSO.CopyFile strMapFile, strPrinter
Set FSO = Nothing
Did not find anything on the conversion process yet. You might be able to simply copy the PDF directly to the printer.
Edit:
I was able to use adobe reader to send a pdf to the default printer using Shell and Command Line
The trick here is to close the new window after Adobe launches. This code opens the window maximized so I can see what is going on. After you get it working to your liking, you could use minimized.
Code:
Dim stAppName As String
Dim strPrintSwitch As String
Dim strPath As String
stAppName = ""
strPrintSwitch = ""
strPath = ""
strPrintSwitch = "/t "
strPath = "C:\Test\test.pdf"
stAppName = "C:\Program Files (x86)\Adobe\Reader 10.0\Reader\AcroRd32.exe " & strPrintSwitch & strPath
Call Shell(stAppName, 1)