Hello...this is my first volvo, a 1990 240DL..and it has my husband and I feeling that we've entered a new world! Right now we have a problem with no heat.
So far we've: changed the thermosat twice
1.) themostat in the car had the stem cracked off so we replaced with 180 degree thermostat. Still no heat

2.) realized possiblity that we could have gotten a bad thermostat so we got direct repacement part from Germany 190 or 195 degree. Still no heat

Other notes..seemed like more coolant came out than went in
...when engine heats up to operating temperatures, no heat in cabin and expansion tank remains unchanged.
...temperature gauge is working
....drive belt tension is ok
.
could this be an air lock problem? What are some steps we should should take next? Any suggestions would be greatly appreciated...(I've gone thru several indexed messages but just getting bits and pieces of related info .) Thanks, Mary & Joe