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No AC blowing, No Heat blowing, hear hiss when turning on AC or heat

I turn my car on. I have no error lights on my dash. The heater and AC control unit lights up. I press the down arrow on my in-dash heater/AC control unit so I can get some cold air. I hear a hissing sound for about 2 seconds, but no air comes through the vents

I get the same effect when trying to use the heater. Quick hissing sound, no air through vents.

Both stopped pushing air at the same time (when my ac stopped working, I tried to put out heat just to check)

I have checked al the fuses under my steering wheel and in the engine compartment using a circuit tester (w/light).

There is an AC Clutch relay fuse in the engine fuse box. Not sure if I should check that.

What should my next steps be. please be as specific as possible (pictures are always helpful).

Thank you.

Add what year, engine, mileage when you get a chance; that will help with the diagnosis. If I were to guess, the main thing the heat and A/C have in common is the fan motor. If it is not working, you won’t feel any air blowing. This may also explain the hiss you are hearing-probably vacuum actuated doors to change direction of air flow-you just may never have heard this since it would be drowned out by the noise of the fan motor.

2001, V8, 120k miles

The HVAC system in your vehicle is totally electronic. No vacuum motors.

And when the HVAC system in your vehicle fails to produce cold/warm air, it’s usually caused by a defective EATC control module.



I will perform the diagnostics listed here and post the results:

It was the blower motor/regulator. I took out the fan and hooked it directly to the battery and it worked.

I then tested that power was getting to the blower motor from the wires.

So I went to AutoZone and purchased a replacement blower motor/regulator and it all worked once it was hooked up.

Now my car gets comfortably hot and the AC works, though not as cold as I wanted.

Thanks for a post back, good to know what worked, and that you got your car’s climate regulated again. Best of luck.