Cheryl,
70 degrees in the tank would be OK. Take a bucket into the room with you and purge the hose before you start cleaning. Unless the hose is draped down the outside of a building on a cold wet day this will give you about the right temperature at the jet, and slightly less at the carpet.
If the flow is interrupted for a few minutes (moving furniture), re-purge the hose to clear the solution that has been sitting in the hose cooling.