a/c stopped on '89 300E

appreciated previous response. Knowing a bit more now I notice the following:
- a/c clutch engages and stays engaged

- the 'fuel-economy-gauge' suggests that there _is_ a load on the engine. One can also hear rpm change a bit etc. when engaging a/c

- climate control appears to work (blower, vent changes, etc) except the air coming out isn't cold.

- fuses are OK

- failure of a/c wasn't slow but occured
between turning car off at night and starting again in the morning.

- very puzzled, guenter. any help appreciated!

p.s. Is a sruck valve reasonable? do I then need to rebuild the compressor?