Gido
Junior Member
The car is a 2010 V6 4.0 **without** dual zone climate control. The driver side is blowing warm air, while the passenger side is blowing ice cold. I've mostly debugged the issue but have a bit more to do. Now it's time to figure out what to do about the issue. Be careful if you are using what I have put here. This applies to the "w/o dual zone", or single zone, system ONLY.
The cars are manufactured such that there are minimal differences between the various models (minimizes production line differences, tooling, and assembly time). The dual zone system uses two independent actuators for the driver and passenger side, while the single zone systems use only one actuator. In addition to that/those actuators, all models will have two additional actuators; one for the inside/recirculate function and the other for the defrost, dash, feet selection. Here's a video of where the actuators are
(sorry, won't paste as a link). You can find diagrams of the components here https://www.americanimportrepair.com/blog/what-happens-when-an-a-c-actuator-goes-bad (scroll down for the single zone system part list). The evaporator assembly for the single zone system is part # DR3Z-19850-C.
If you have a single zone system, the inside of the evaporator assembly still has 2 separate doors, one for the driver side, and one for the passenger side. The difference is, for the single zone system the door hinge points are connected together (likely with a keyed sleeve, versus a smooth sleeve) INSIDE THE EVAPORATOR ASSEMBLY, meaning the two doors move together as actuated by the single actuator on the passenger side. You can look up under the steering wheel towards the center console (on the side of the evaporator assembly) and see the faded white (my son called it pearl color) round piece sticking out of the evaporator assembly, and a few alignment posts and unused screw holes. That's where the driver side actuator would go for a dual zone system (but the white piece would have teeth inside to engage the actuator, as opposed to smooth such as for the single zone system). If you put your fingers on that white piece and change the temp setting (with the car running), you may feel that piece rotate... or you may not. I did feel the piece rotate. There are likely several different failure modes that result in similar symptoms (more on that below).
This is as far as I've debugged. I ordered an endoscope (camera on the end of a cord) to shove in the left center vent to see if I can witness the door moving as I adjust the temp. I know it moves some since the air goes from 135 deg F air to 85 deg F air on the driver side of the car when I go from full hot to full cold (passenger side goes from 135 deg F down to 58 deg F). It could be that something fell down there and is stopping the door from completely closing, or it could be that the door is slightly damaged but not completely broken. I know the door shaft/hinge and the connecting piece to the passenger blend door (or it could be one solid piece with two doors) are good because the shaft on the driver side turns when the temp is changed. But something has failed for sure... just not exactly sure what that failure mode is yet. Here's a good site to check out with illustrations and videos of what I'm talking about (though not on a Mustang), https://www.americanimportrepair.com/blog/what-happens-when-an-a-c-actuator-goes-bad. They show a broken door, and they talk about a bad actuator. My actuator is NOT bad, but my door may be broken (though not like the one in the video because, again, I can feel the shaft turn on the driver side and it is SOLID, meaning I cannot turn it by hand). If you don't feel the piece rotate at all, or if it is moveable by hand, it might be that the keyed sleeve inside the evaporator assembly broke, or that the blend door hinge/shaft broke (see the bit on the American Import Auto site listed above).
Lastly, regardless of what my specific failure mode is, the end all be all answer is to replace the evaporator assembly. I haven't researched what that involves, but from what I've seen, the ENTIRE dash has to come out. Looks like you can replace just the evaporator core or the heater core by itself, so you likely don't need to break into either of those systems (which means a lot less special equipment, expertise, time, and dollars). For now, I've ordered a heater core bypass valve from Amazon (https://www.amazon.com/gp/product/B0CWD39QNV/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1) to keep the heater core from even getting hot. It's not going to "fix" the problem, but it will make it a lot less noticeable, especially on recirculate setting.
I'll come back and post more once I'm able to scope the blend doors. If anyone else has experience with this issue, I'd love to hear what you did. If you replaced the evaporator assembly, I'd love to hear how difficult it was. I'd also LOVE to know how to get the center rectangular vents out as that would make it much easier to scope.
The cars are manufactured such that there are minimal differences between the various models (minimizes production line differences, tooling, and assembly time). The dual zone system uses two independent actuators for the driver and passenger side, while the single zone systems use only one actuator. In addition to that/those actuators, all models will have two additional actuators; one for the inside/recirculate function and the other for the defrost, dash, feet selection. Here's a video of where the actuators are
If you have a single zone system, the inside of the evaporator assembly still has 2 separate doors, one for the driver side, and one for the passenger side. The difference is, for the single zone system the door hinge points are connected together (likely with a keyed sleeve, versus a smooth sleeve) INSIDE THE EVAPORATOR ASSEMBLY, meaning the two doors move together as actuated by the single actuator on the passenger side. You can look up under the steering wheel towards the center console (on the side of the evaporator assembly) and see the faded white (my son called it pearl color) round piece sticking out of the evaporator assembly, and a few alignment posts and unused screw holes. That's where the driver side actuator would go for a dual zone system (but the white piece would have teeth inside to engage the actuator, as opposed to smooth such as for the single zone system). If you put your fingers on that white piece and change the temp setting (with the car running), you may feel that piece rotate... or you may not. I did feel the piece rotate. There are likely several different failure modes that result in similar symptoms (more on that below).
This is as far as I've debugged. I ordered an endoscope (camera on the end of a cord) to shove in the left center vent to see if I can witness the door moving as I adjust the temp. I know it moves some since the air goes from 135 deg F air to 85 deg F air on the driver side of the car when I go from full hot to full cold (passenger side goes from 135 deg F down to 58 deg F). It could be that something fell down there and is stopping the door from completely closing, or it could be that the door is slightly damaged but not completely broken. I know the door shaft/hinge and the connecting piece to the passenger blend door (or it could be one solid piece with two doors) are good because the shaft on the driver side turns when the temp is changed. But something has failed for sure... just not exactly sure what that failure mode is yet. Here's a good site to check out with illustrations and videos of what I'm talking about (though not on a Mustang), https://www.americanimportrepair.com/blog/what-happens-when-an-a-c-actuator-goes-bad. They show a broken door, and they talk about a bad actuator. My actuator is NOT bad, but my door may be broken (though not like the one in the video because, again, I can feel the shaft turn on the driver side and it is SOLID, meaning I cannot turn it by hand). If you don't feel the piece rotate at all, or if it is moveable by hand, it might be that the keyed sleeve inside the evaporator assembly broke, or that the blend door hinge/shaft broke (see the bit on the American Import Auto site listed above).
Lastly, regardless of what my specific failure mode is, the end all be all answer is to replace the evaporator assembly. I haven't researched what that involves, but from what I've seen, the ENTIRE dash has to come out. Looks like you can replace just the evaporator core or the heater core by itself, so you likely don't need to break into either of those systems (which means a lot less special equipment, expertise, time, and dollars). For now, I've ordered a heater core bypass valve from Amazon (https://www.amazon.com/gp/product/B0CWD39QNV/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1) to keep the heater core from even getting hot. It's not going to "fix" the problem, but it will make it a lot less noticeable, especially on recirculate setting.
I'll come back and post more once I'm able to scope the blend doors. If anyone else has experience with this issue, I'd love to hear what you did. If you replaced the evaporator assembly, I'd love to hear how difficult it was. I'd also LOVE to know how to get the center rectangular vents out as that would make it much easier to scope.
