Search for AD User without AD module 
# search based on SamAccountNamer
$strFilter = "(SAMAccountName=$username)"
$objDomain = New-Object System.DirectoryServices.DirectoryEntry
$objSearcher = New-Object System.DirectoryServices.DirectorySearcher
$objSearcher.SearchRoot = $objDomain
$objSearcher.PageSize = 1000
$objSearcher.Filter = $strFilter
$objSearcher.SearchScope = "Subtree"
# Add additional properties to return here
$colProplist = "name","SAMAccountName"
foreach ($i in $colPropList){
    $foo = $objSearcher.PropertiesToLoad.Add($i)
}
$colResults = $objSearcher.FindAll()
# formation output results
[System.Collections.Generic.List[PSObject]] $results = @()
foreach ($objResult in $colResults){
    $properties = @{}
    $objResult.Properties.GetEnumerator() | ForEach-Object{
        $properties.Add($_.Key,$_.Value[0])
    }
    $results.Add([pscustomobject]$properties)
}
$results
Details
This snippet will allow you to search for an Active Directory user without needing to install the Active Directory PowerShell module

Example
PS C:\> $username = "*svc*"
>> $strFilter = "(SAMAccountName=$username)"
>> $objDomain = New-Object System.DirectoryServices.DirectoryEntry
>> $objSearcher = New-Object System.DirectoryServices.DirectorySearcher
>> $objSearcher.SearchRoot = $objDomain
>> $objSearcher.PageSize = 1000
>> $objSearcher.Filter = $strFilter
>> $objSearcher.SearchScope = "Subtree"
>> $colProplist = "name","SAMAccountName"
>> foreach ($i in $colPropList){
>>     $foo = $objSearcher.PropertiesToLoad.Add($i)
>> }
>> $colResults = $objSearcher.FindAll()
>> [System.Collections.Generic.List[PSObject]] $results = @()
>> foreach ($objResult in $colResults){
>>     $properties = @{}
>>     $objResult.Properties.GetEnumerator() | ForEach-Object{
>>         $properties.Add($_.Key,$_.Value[0])
>>     }
>>     $results.Add([pscustomobject]$properties)
>> }
>> $results
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