Broken Temperature Gauge

Hey I'm looking for some help and any insight that could solve my problem would be appreciated. I have a 92 GS. Like the title says the temp gauge is broken. It never moves at all. After reading through numerous threads I changed the temp sensor and still nothing. Its also still blowing out cold air but I supposed thats because of it not being the read that the car is warmed up. While working on this problem I took out my instrument cluster also. Accidently the plastic piece that covers the gauges came off so I decided to see if the temp needle was broken. It has no sort of hold on it is the best way I can describe it while the 3 others atleast have sometime of pull or hold. Does that mean a broken gauge or needle? Or could it be another problem? Thanks for the help.

Check the valve on your heater core. It sounds like it isn't opening.

Would that explain why my temp gauge isnt working?

From what I remember, the temp sensor is down flow of the heater core valve. So it's possible.

Ok if the valve is stuck closed how would I fix it to make sure it opens when the heat is on?

Well you should make sure that the cable is attached to the heater core valve and make sure the valve is still moving. Changing the valve is a distinct possibility. Also, you might want to change out the heater hoses back there just for the piece of mind and it's like $15 in hose. When you do, be careful not to bend the copper tubes coming out of the heater core. Cut the old hoses off the heater core with a razor blade. Don't just crank down on it with a pair of pliers. If you damage the heater core it's a bitch to replace. Replacing the heater core requires removing the dash.