Automotive Air Conditioning Information Forum

Hi all, I haven't had any luck figuring out what's wrong with my Accord, hoping someone here can point me in the right direction. I have an 07 Accord EX-L. About a month ago it suddenly starting dumping *hot* air (not ambient temperature) on the driver side while the passenger side blew ice cold (yes, I checked to make sure dual zone wasn’t turned on). Some factors which might set my case apart:

1. The problem went away after about an hour of highway driving. Since then, it's acted up twice, where the hot air suddenly appears and then after some hours or days goes away again.

2. I took the car to a mechanic today, who ran his diagnostics and found nothing wrong -- as luck would have it, the AC was working fine when he turned it on.

3. The climate control system’s temperature setting has always been wonky (I bought the car used four years ago). For a comfortable temperature in the summer the temp needs to be set to about 26C degrees (79F), but the air coming out the vents is much cooler. I replaced the cabin temperature sensor right after buying the car but that didn’t make a difference. I've half-convinced myself this particular problem is caused by some super expensive electronic circuit board that requires taking the entire dash apart.

4. There are no HVAC codes flashing when I run the internal DTC test.

5. No problems with blowing heat on either side with engine running.

I'm wondering if the intermittent nature of the problem helps to narrow down the issue, combined with the fact that apparently the system doesn't have any obvious problems (doesn't need to be charged). I'm starting to wonder if a faulty temperature blend servo on the driver's side might make more sense given the sudden ON/OFF problem - could refrigerant issues cause that? Presumably electric gremlins could. FWIW, this driver hot/passenger cold issue is well documented with Accords from that generation, and the problem most often is that the system is undercharged.

Any thoughts appreciated.

I'm not an expert on Honda A/C systems. But because you're getting heated air (not just ambient air) out of the driver-side dash vent and nice cold air out of the passenger-side vent, it seems to me that the most likely cause of the problem is a faulty left-side blend-door actuator.

You could test for this by removing the actuator and operating the blend-door lever by hand while the A/C is running. If you get heated air while moving the lever to one end of the slot and cold air while moving it to the opposite end, the actuator is probably shot.

Given the age of your vehicle, the problem could also be a low charge. But I think I'd focus on the blend-door actuator first. If it's not that, then you could go ahead and recover the charge, or have it recovered, to determine exactly how much refrigerant is in the system by weight. If it's low, then it's on to finding the leak(s).

My reference material says that your vehicle's capacity is 19.00 ounces of R-134a.

Agreed, I think it's worth the time to dismantle the part of the dash housing the blend door motor. If nothing else, I don't need to pay anyone to do that and I don't need any special AC equipment to do a bit of troubleshooting myself. I'll post something once I've made some progress.

EDIT: the problem happened again. This time I cranked the heat up to full blast (both sides) and let it run for a couple minutes while driving. Then turned down to maximum cold and the problem disappeared. I tried this trick the first time I had the problem and it didn't make a difference but given that the problem is intermittent and disappeared when I changed the temperature, it feels more like an electrical problem to me, so I'm going to start by tackling the motor/servo that controls the drivers-side temperature blend door. Replacement part is about CAD$140. We'll see.

It's sure looking like the problem is a faulty blend-door actuator. But before you spend the money for a new one, try the test mentioned earlier. In any event, let us know how it goes.

Today I removed the temperature blend door actuator. I only removed the actuator, opened it up and applied some dielectric grease to the gears. Since the part is $130, I'm hoping what I did might have solved any minor electrical issue. Of course, being an intermittent problem there's no way to tell immediately if this made a difference - I'll just have to wait and see if the problem recurs. Definitely check out the YT videos below to see how the part is extracted (videos of Accords and also the Odyssey which is very similar). Then start with a repair attempt. If repair fails, there's a very interesting video about using a Cadillac part for $15 instead of the Honda part as they are nearly identical. IMPORTANT: make sure you mark or photograph where exactly the white plastic piece is situated on the rest of the part before you take the actuator apart -- once you take it apart the white piece spins freely and you won't be able to re-install it because the male pins won't line up with their female counterparts in the dash. The cheapest option is to start with the repair, but bear in mind extracting and installing the actuator is a PITA as you have to pretzel yourself under the dash, and you'll need some source of light so you can see what you're doing. You might want to consider skipping the repair if you don't want to take the risk of having to replace it if the repair fails. I found by far the best position was to lie on back with both feet outside the car on the ground.

How to attempt repair: https://www.youtube.com/watch?v=jWcWUlbksco

Cheap Amazon/Cadillac option: https://www.youtube.com/watch?v=kTd2UW1NDRA

General removal instructions:
https://www.youtube.com/watch?v=1nQnlqdlrQw
https://www.youtube.com/watch?v=IuekQMwy3sw

I also uploaded some pictures of the actuator guts: https://imgur.com/a/HIXojyl