'98 Taurus with no heat

Maintenance/Repairs
1

I realize these cars are notorious for heating problems, but I was wondering if someone could give me some advice. I have had this problem before, and flushed out the heater core which fixed it. Now after about 18 months I am having it again. The blower blows and the temp is getting up, but no heat is blowing through the vents. In the summer it was overheating when the AC would be turned on, so I went all summer without using the AC. I changed the thermostat twice, still nothing. Have flushed out the entire system, including the heater core at the firewall, still no heat. Could this be a sign that the water pump is bad? I have no leaks. One thing I do notice is that the air at the passenger side vents seems to be just a bit warmer than the air at the driver’s side. Also, when I am excellerating, the blower seems to blow harder and I get a little heat, but when the RPM’s come back down, no heat.

Any advice is appreciated.

2

Most of the airflow through the ductwork is probably controlled by engine vacuum. The variations you get when accelerating would have me checking the vacuum lines that feed the cabin - they’ll be along the firewall and down under the dash.

3

If both inlet and return line to the heater core at the firewall are hot ( same temp ) then you have a vacuum actuated door blend problem.

4

There’s also an electric blend door motor which could be the culprit.

If those doors stay closed ( vacuum or electric ) you wont’ feel the air that the fan is blowing.