79 Corvette Clean Evaporator/Weak Blower Motor
Thread Starter
Advanced
Joined: Apr 2023
Posts: 70
Likes: 7
79 Corvette Clean Evaporator/Weak Blower Motor
I have plans to do a little trip with my C3 in a little less than a week. I know I wont have the greatest and coldest A/C ever with the old system, but I'm hoping to squeeze as much as I can out of it.
I recently upgraded the blower motor from the stock one to a C4 blower motor with a spacer. But I noticed really no improvement on airflow. To be honest the first two speeds of the fan barely move any air into the cab, and the high speed is just okay. I get they won't be quite like a modern car, but maybe my expectations are still to high.
I was thinking my evaporator probably needs cleaned out regardless, being we have a lot of pollen tassels out here, they can easily snake their way into there. Was wondering what the best way is to clean out the evaporator. I've heard of using some chemicals through the evaporator drain before, but don't know how well they would work. TIA.
I recently upgraded the blower motor from the stock one to a C4 blower motor with a spacer. But I noticed really no improvement on airflow. To be honest the first two speeds of the fan barely move any air into the cab, and the high speed is just okay. I get they won't be quite like a modern car, but maybe my expectations are still to high.
I was thinking my evaporator probably needs cleaned out regardless, being we have a lot of pollen tassels out here, they can easily snake their way into there. Was wondering what the best way is to clean out the evaporator. I've heard of using some chemicals through the evaporator drain before, but don't know how well they would work. TIA.
Thread Starter
Advanced
Joined: Apr 2023
Posts: 70
Likes: 7
How would I go about this? I thought it was controlled by a change in voltage, but when connecting the purple wire (blower motor +) to a multimeter it just shows roughly 14V regardless of fan speed. All fan speeds do work, just not well with airflow.
Last edited by Joey White; Today at 03:21 PM.
Race Director
Joined: Nov 2006
Posts: 13,252
Likes: 7,841
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
I put in C4 blower motor in my car a few years ago. Really made a difference. I also put in a much heavier ground wire for the blower on advice from members on here.
As per properly cleaning out the heater/evaporator box. These do get plugged up with debris. Take the box apart. No simple way.
Make certain that cooler tube from box to the blower motor is hooked up and clear as well.
As per properly cleaning out the heater/evaporator box. These do get plugged up with debris. Take the box apart. No simple way.
Make certain that cooler tube from box to the blower motor is hooked up and clear as well.
Last edited by 4-vettes; Today at 05:30 PM.
Thread Starter
Advanced
Joined: Apr 2023
Posts: 70
Likes: 7
I put in C4 blower motor in my car a few years ago. Really made a difference. I also put in a much heavier ground wire for the blower on advice from members on here.
As per properly cleaning out the heater/evaporator box. These do get plugged up with debris. Take the box apart. No simple way.
Make certain that cooler tube from box to the blower motor is hooked up and clear as well.
As per properly cleaning out the heater/evaporator box. These do get plugged up with debris. Take the box apart. No simple way.
Make certain that cooler tube from box to the blower motor is hooked up and clear as well.
Race Director
Joined: May 2006
Posts: 18,740
Likes: 2,583
The resistor is on the evaporator core box in the engine compartment held on by 2 screws. Remove it and visually examine it for any broken wires.
Race Director
Joined: Nov 2006
Posts: 13,252
Likes: 7,841
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Pin hole leaks probably are not a big problem. Leaves and debris are. There isn't a screen on the intake. Stuff gets in there. Lots of stuff. When I did my blower motor. I found leaves and pine needles sticking out the coolant tube hole when I went to adapt the C3-C4 cooler tube. (Spliced the two together in the center). Anyway. It was obvious the box needed a clean out.
