02 No Heat

O2 mountaineer 4.6 awd. After warming up for about 5 mins left for work, turned on heat and only got cold air. Once I got on the express way the air got warmer and then seemed normal. Now it blows cold all the time. Any suggestions would be appreciated.
Art

The heater control valve is on the right side of the engine.Just follow the heater hoses. The valve is vacuum controlled. Check the vac tubing/hose going to it for vacuum when the eng is running and the heat is on.Check the tubing for breaks,melting,kinking,etc. The valve is known to be a piece of crap.

Thanks, I looked at the valve and noticed that a tiny hose that attaches to the top was disconnected. I reconnected it, and no difference. I am going to replace the valve anyway. Also my wife drove it today to the store, and said that as she pulled in to the parking lot, the check gauge light came on and the temperature gauge was high. She ran in for 5 minutes came out started the car, watched the temp gauge and it was back to normal, and was normal all day. Could the hcv cause this to happen also. My son said this temp issue has happened twice before.