Help! defroster/vent airflow very low

[mrroadhouse]

88 coupe. I'm about to dig into my 88 coupe and try and find out why the the airflow from the defrost and vents is barely anything at all. Fan speed changes (sound) and temp does too. Would appreciate any help about how to get to the possible places an obstruction could be. ECC head and vaccume module have been checked and working. no vaccume leaks !

 

[CAJUN C4]

You might have to clean your evaporator. They will clog over time and air flow greatly reduced.Take the fan blower motor off this will give you access to the evaporator.Might Take a damp rag and wipe and then hose it out.