2003 taurus starts over heat with a/c on

My 2003 Taurus over heats when the a/c is running.
Turn the a/c off and it cools down within a minute or so.
Also my blower blows cold air which is just as cold as my a/c.
every time i take it to a garage the car wont over heat on them. But they put the a/c on and just leave the car running and it doesn't over heat for them.
anyone with any ideas thanks.

When the car overheats for you, is it only when you are driving it or is it only when the car is not moving? If not moving, check for operation of the radiator cooling fan. Maybe you have an intermittant radiator cooling fan that for some reason doesn't have the problem when you've taken it to the shop.

Does it happen 100% of the time for you in that condition, or only sporatically? If you can cause it to fail 100% of the time on a certain drive, see if one of the technicians will go for a ride with you to see what's happening.

In addition to check the operation of the radiator cooling fan, you may want to have the radiator cap pressure tested.

Also, make sure your defininition of "overheat" is consistent with what the shop expects. Does the heat gauge just get above the halfway point but you never experience boil over?

-Rod