I have read many of the threads regarding low cold water pressure, but haven't yet found one that specifically applies to the bathroom sink. The house was built in the early 1900's, but was renovated in 2005 so it has copper pipes which cant' be much more than 2 or 3 years. The sink has separate knobs for hot and cold. I think that the problem was relatively sudden. The pressure was fine until I had to have a plumber come and flush out a very backed up pipeline. Soon after he did the work the cold water started coming out very slowly. I thought it might be something simple that I can fix myself instead of calling him back out.

There is a shut off valve underneath the sink... separate ones for hot and cold. And the Faucet Connector is a Brass Craft Engineered Polymer Braid (B1 12AF).

Aside from being able to read and observe what information was asked for in the other posts I saw, I know NOTHING about plumbing, so please give detailed instructions if you can.

Thanks!

The plumber should not have disturbed your cold supply by cleaning out a backed up pipe, I'm assuming a drain. However, you never know and it doesn't matter at this point, you need to fix it. Your cold valve stem or cartridge is getting plugged with debris and there are two ways to fix it, both start with closing the cold supply stop under the sink. Remove the bonnet packing nut under the handle and then opening the faucet and keep turning until the stems comes out in your hand. Remove small bit of debris and flush it. Before reinstalling put a towel over the opening and have someone else open an close the stop, this flushes the line a bit. Reinstall and you should be good to go. The other solution is something a plumber would not do but it works in most situations. Shut off the stop and disconnect the line from the stop that goes up to the faucet. Hold a bowel of water under the spigot so it is under water. Take shop vac to the open end of the supply line and suck the bowel of water backwards through the faucet and valve. You may need to cup your hand over the vac/supply line connection.

Thanks for your response. I'll give it a shot.