air conditioner problems

My air conditioner compressor went and broke the belt along with it.
My husband replaced them and tried to charge the compressor, but it wouldn't work so he brought it to a shop and they said the seals are leaking.
The car is running very sluggish when you step on the gas - the shop said that it will run better when the compressor is fixed - is that true?
Also, the service engine soon light is on - is that also due to the compressor?
Thanks.

The shop is right about the car running better with the compressor. But the light, thats a problem that a lot of GM's have. Its nothing to worry about. As long as its bring it in for relugar tune ups and oil changes your car is in no danger.

Help - I brought it to the shop to replace the air compressor and they wanted to charge me over $500, not including the price of the compressor. They said I needed a new receiver/drier - that it was bone dry - is that a part that usually needs to be replaced?
Also I hear a rattling noise under the car when I step on the accelerator and the car starts off sluggish. Any ideas?
Thanks.

The sluggish condition you describe is usually an indication of a clogged catalytic convertor. You can check this by disconnecting the exhaust system just in front of the convertor and test driving the car to see if acceleration improves. If acceleration improves you will need to change out the catalytic convertor. Check with Auto Zone for a price lower :2cents: than a Cadillac dealership and it may even come with a lifetime warranty. You may want to change out the oxygen sensors at the same time which will pobably improve your fuel mileage.
As for the A/C problem; it is best practice to change out the reciever/dryer when a compressor fails. There is a low cost needle valve that usually is replaced at the same time. Check with Auto Zone.