Dodge Repair: 90 new yorker: autotemp no heat

Question
QUESTION: Hi Roland the new yorker autotemp blows only cold air.  Fan speed control works properly, temp control registers up and down inputs on display properly, air output selection works properly and a/c makes lots of cold air.  Engine thermostat is good and temp gauge reads up as normal.  Heater hoses are both hot.  Autotemp self test performs as normal and comes up with error code 01.  Please advise what i should check next.  Thanks,  Monty Bruckman

ANSWER: Hi Monty,
I have the '89 and '91 manuals and they differ so the first thing is to see which manual applies to your '90. On the control panel is the left most upper button labeled "AC" or does it have a "snowflake" symbol?
When you did the self test did the air get warm momentarily or did it stay cold throughout the test?
I suspect that the blend-door actuator may be the problem but lets do the procedure to be sure.
Let me know.
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland, the upper left button says AC and when i did the self test the air did not get warm however the fan only stayed on full speed a very short period like 1-2 seconds then went way down and the error code 01 came up on the display.  Should the fan run full speed longer?  Do I need to hold the three buttons in to properly conduct the self test or just momentary?  Is that actuator an electric motor or is it vacuum ?  Thanks,  Monty

Answer
Hi Monty,
That control button is like the one shown in the '89 manual so I will use that. You did the test correctly. The only issue is fault code 1. The power for the blend air door which is  electrical is powered by fuse #11 so check that first.
Then the instruction is to remove the blend door actuator and with wires still connected to it try the test again. If the code goes away then move the blend door shaft to which the actuator was attached to check for binding up. If code doesn't go away then there are about a half a dozen electrical tests that need to be done. I can photocopy the page that lists those tests and postal mail that to you. But for now I would check the fuse, remove the actuator and run the test again.
The actuator is on the bottom of the HVAC under the dash at the far left end of it (just to  the right of the center stack/above the floor hump). It is a flat square box. You have to remove the floor air distribution duct to begin (that may require removal of the lower edge of the instrument panel, but I am not certain). Then when you see the actuator box you will find to screw on the underside that you remove to drop the box off the bottom of the HVAC Unit. You will see the shaft of the blend door sticking down which had been mated to the actuator, noting its rotational position for when you reassemble.
The do the test again and see if the code goes away or not.
Roland