2007 Civic: fans blow sometimes, no heat (constant A/C)


#1

CURRENT PROBLEM:
The fans don’t blow any air after about 30 minutes of driving/once the car has warmed up.
Also, A/C seems to permanently be on even if I don’t have the A/C button on, but the fan problem is the main issue
(There has been a loud hum behind the dash (for over a year) that speeds up the faster I set the fan speed so the motor is going but no air comes out.)

What’s happened in the past:
#1. Last summer the A/C stopped working. Will have to look back at receipts more to see exactly what was done (not sure if it worked through winter).
#2. Basically the heat only came out of the vent to the left of the steering wheel all winter (no air came out of other vents or it barely came out but was cold).
#3. A/C wasn’t blowing cold so they replaced thermo switch. When they did this, car wouldn’t do anything so they replaced the computer (fortunately I didn’t pay for that).


#2

Did ac work after computer was changed? I am assuming yes since u say no other parts were changed after that. If shop changes computer $$ and ac did not work at that point, u would have said so


#3

Sounds as if your fan is going bad. There are motors that drive the blend and mix doors and control where the air comes out. The AC will be on IF the system is sensing that it is in the defrost mode. Here is a diagram of the system. There is a relay for the blower and a transistor also. If it is blowing but not coming out of the correct place, it could be the motors or the control head.