A/C blower issues

[shgreen1970]

Ok, this is going to sound strange. The fans blow out the dash vents just fine when I first start the AC. After a while (10 or 15 minutes) the fan is still running and sounds perfectly normal. However there is very little air being blown out the dash vents, or any vents for that matter. I hear it running, but no air movement. If I turn the speed control up to high it will start blowing normally again. If I then move it back to low speed it will again work for a while, then no air movement. Any thoughts where I should start looking first?

 

[Chris]

Ok, this is going to sound strange. The fans blow out the dash vents just fine when I first start the AC. After a while (10 or 15 minutes) the fan is still running and sounds perfectly normal. However there is very little air being blown out the dash vents, or any vents for that matter. I hear it running, but no air movement. If I turn the speed control up to high it will start blowing normally again. If I then move it back to low speed it will again work for a while, then no air movement. Any thoughts where I should start looking first?

One of the most common issues is a failing blower motor resistor. It might be causing the lower speeds to work intermittently. This is likely where I'd start.

I'd also check to see if there are any obstructions in the ducting system. Leaves, debris, or even a critter could be blocking airflow after running for a while.

If you haven't changed the cabin air filter recently, a clogged filter can restrict airflow and affect performance.

Even though it sounds like the motor is running fine, it may be worth testing or replacing the blower motor itself. Sometimes they can lose efficiency over time.

Finally, there could be an issue with the HVAC speed selector switch. If it’s not functioning properly, it may not maintain power to the blower motor at lower speeds consistently.

Keep us posted on what you find!

 

[KennethS]

Maybe a slow vacuum leak? I think loss of vacuum will divert the air flow to the heater vents.

 

[shgreen1970]

One of the most common issues is a failing blower motor resistor. It might be causing the lower speeds to work intermittently. This is likely where I'd start.

I'd also check to see if there are any obstructions in the ducting system. Leaves, debris, or even a critter could be blocking airflow after running for a while.

If you haven't changed the cabin air filter recently, a clogged filter can restrict airflow and affect performance.

Even though it sounds like the motor is running fine, it may be worth testing or replacing the blower motor itself. Sometimes they can lose efficiency over time.

Finally, there could be an issue with the HVAC speed selector switch. If it’s not functioning properly, it may not maintain power to the blower motor at lower speeds consistently.

Keep us posted on what you find!

Thanks. I'll likely get into it this weekend and I'll keep everyone posted.