Nissan Repair: 97 Altima no heat, heater control valve, vacuum source

Question
(97 Altima)I have no heat in my car so I just had a new thermostat put in my car to hopefully fix it.  The mechanic told me there is air bubbles getting into my coolant some way or another.  Does this have to be fixed to repair my heat? Which still doesn't work.  My air conditioning works great.  Every now and then my heat will hop on and stay on until I turn off the car....  I noticed as soon as I got the car back the fans near the engine stay on about 30 seconds after I turn off my car.  Is there a cheep repair I can have done to fix my heat issue?  It's cold out there!

Answer
Hi Allen -

Try checking the heater control valve. Follow the heater hose from the engine, and as you get closer to the firewall, you should run into it. It is in line with the hose, and should have a vacuum hose connected to it. Apply vacuum to the valve and it should move. If not, then replace the valve. If there is no vacuum when engine running and heater turned on, then check the hose for leaks or the vacuum source.

If all is OK, then another thing to check is the air door in the ductwork of your A/C. This is located below dash passenger side. Sometimes the door is stuck and will not channel the warm air into the cab. Once the door is freed, apply grease to the gasket so future binding does not occur.

Hope this helps
aloha
calvin