Heater Question

I have an ongoing problem with our Plymouth Voyager '99 3.3L van. Not much heat in cabin.
Here are symptoms:
*Replaced thermostat with 195 Degree - NEW
*Fluid Levels Fine *Calibration test seems fine *Fan works in all speeds *Did not have system flushed - was making an appointment to do this and the fellow told me it would not help! *The heater gets warm - sometimes hot but it is as if there is an air leak and cold air is blowing in with the warm/hot air. Anyone ever have this problem? We were in a snowstorm last night and traveled for miles at about 30 mph. The heat got hot then kinda went through a cycle when it seemed to blow cool and then cold air with the hot. I know the blend door motor is working - you can hear it. Not sure if it closes fully though. How can I inspect this?
Any suggestions?
JOHN
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

into the heater core at the firewall. If they are hot going in and hot going out you possibly have a problem with the blend air door. If it is hot in and cold out the heater core is stopped up.
Glenn Beasley Chrysler Tech
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Maxpower, if the heater core is stopped up, would a regular flush solve the problem, if so can i just hook it up to a waterhose. Or is there an easier way? Thanks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You can try that but I have never had any luck doing that. it gets so crystallized a back flush normally doesn't work
Glenn Beasley Chrysler Tech
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hey John,
I had the same trouble with ford Areostar after paying $300.00 I found out that a ink pen had fallen down my defrost vent and wasn't allowing my door to open or close all the way.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.