Hello, I'm Chris. Thanks for visiting Just Answer.
Normally a vacuum issue causes all the air to come out the defrost but in your case you have no defrost so this will be a vacuum control concern at the climate control switches or a concern with the mode door or actuator. This repair may require removing the dash. Do you need the pinpoint test and diagrams?
Can I get a diagram of the heater system/
I looked at the wrong year prior, yours is all electronic, it does not have vacuum supply you need to check the electrical function of the selector and function control motor and verify the signal is getting to there as well as able to move the mode doors, see the information below.
All heater controls work and blow in the proper outlet, except for the defrost button - which seems to do nothing and nothing comes out the defrost vents.
At the function selector you need to see if you can command air flow to come out of the defrost manually operating it. If not then the dash has do be removed to repair the broken mode door.
Will have to try that and then see from there. Is the function selector visible from under the dash?
Thank you. Will try and reply.
Made temp fix to get defrost to work tilll time allows dash to come out
Glad you got it working.
Question on same car Accura 1991. Car drives for about 20 minutes and dies some time it starts again , but some time I have to tow back to house and wait hours before it will start again. Suggestions?