5000 Without Heat

["Bill" <billfree@interlynx.net>]

My 88 5000TQW has no heat, the temp gauge says its up temp but no heat. I
can adjust from vent defrost to floor but no heat. I installed a new
electronic controller this summer, since the air only vented through the
defrost mode. The air worked great all summer. My son has been driving it
since Aug., and just told me he was freezing(this is Canada).I also put a
new thermostat in this summer as well. Has anyone have any suggestions

Bill