Formula too long - Nested IF statement with VLOOKUP

I have written a formula using a nested IF excel function. It tests a cell for a particular string and returns a "looked-up" value according to that test.

This works fine BUT.... i need to add more testing conditions to the IF statement.

Can anyone give me a clue how to condense this formula or do something like a CASE statement which will not restrict the number of IF tests that i can perform?

=IF((ISNUMBER(SEARCH(" LS",A3))),VLOOKUP("LS",AR1:AS9,2,0),IF((ISNUMBER(SEARCH(" NLS",A3))),VLOOKUP("NLS",Sheet2!$A$2:$B$12,2,0),IF((ISNUMBER(SEARCH(" TQ",A3))),VLOOKUP("TQ",Sheet2!$A$2:$B$12,2,0),IF((ISNUMBER(SEARCH(" KS",A3))),VLOOKUP("KS",Sheet2!$A$2:$B$12,2,0),IF((ISNUMBER(SEARCH(" DB",A3))),VLOOKUP("DB",Sheet2!$A$2:$B$12,2,0),IF((ISNUMBER(SEARCH(" LD",A3))),VLOOKUP("LD",Sheet2!$A$2:$B$12,2,0),"900x1900mm"))))))

Data in the Sheet2 array is:
Size Name Dimensions
LS 900x2030mm
KS 1070x2030mm
TQ 1070x1900mm
NLS 760x2030mm
DB 1370x1900mm
LD 1370x2030mm
QU 1520x2030mm
KG 1830x2030mm
DQ 1520x2030mm
DK 1830x2030mm
KC 1520x2030mm
QC 1830x2030mm

An example of data in the cell being tested is:
FHC321 LS
FHC321 NLS
FHC321 KS
FHC321 LD
FHC321 QU
FHC321 KG
FHC321 DQ
FHC321 DK
FHC321 QC
FHC321 KC
FHC321C LS
FHC321C NLS
FLE321 NLS
FLE321 LS
FLE321 KS
FLE321 LD
FLE321 QU

So, I need to add tests for QU to QC in my lookup table.

Your help is much appreciated.

Regards, FurniKing