OK, so I'm just posting this in case it might help someone else now or in the future. 2008 xc70, the air conditioning started malfunctioning a few months ago, and I noticed that it occurred when the ambient temperature on the dash was displaying the dreaded "- -".... obviously, the ambient temp sensor was also malfunctioning, and if you're here, reading this, you've probably figured out by now that the ambient temp sensor directly affects the air conditioning system. I won’t explain how.. you can look that up.. but it’s a wonderful piece of Volvo over-design.
So anyway, I tried everything I could find as a solution. Replaced the sensor twice, didn’t work. Read all about possible corrosion in all the different harnesses and door control modules. I tore down the door, de-pinned and cleaned with sandpaper and solvent everything I could get to. Nothing worked. I even read on this website about a guy who clipped the wires at the ECM and re-ran the wires and sensor to the grill which worked, which I was about to try… but I’m way too hard-headed to believe in electronic gremlins, and wiring reroutes.
Somewhere, I also saw someone mention that the wire had split in the door near the hinge. I had previously inspected and cleaned the harness there and thought everything looked good. Unfortunately, I didn’t dig deep enough. On second look, with the door removed for full access, I found the culprit.
Here, in the wiring just after the door harness connection, going into the body, an inch or two inside the waterproof casing, the wires are held in place by a tight fitting zip-tie (removed in these photos) which caused some of the wire insulation to split from movement, and, in the case of the temp sensor wires, to completely break.
So, look there… if you’re getting the bizarre temp readings and intermittent a/c, before you even order that sensor to replace it, look here first. It might save you weeks of hunting.
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So anyway, I tried everything I could find as a solution. Replaced the sensor twice, didn’t work. Read all about possible corrosion in all the different harnesses and door control modules. I tore down the door, de-pinned and cleaned with sandpaper and solvent everything I could get to. Nothing worked. I even read on this website about a guy who clipped the wires at the ECM and re-ran the wires and sensor to the grill which worked, which I was about to try… but I’m way too hard-headed to believe in electronic gremlins, and wiring reroutes.
Somewhere, I also saw someone mention that the wire had split in the door near the hinge. I had previously inspected and cleaned the harness there and thought everything looked good. Unfortunately, I didn’t dig deep enough. On second look, with the door removed for full access, I found the culprit.
Here, in the wiring just after the door harness connection, going into the body, an inch or two inside the waterproof casing, the wires are held in place by a tight fitting zip-tie (removed in these photos) which caused some of the wire insulation to split from movement, and, in the case of the temp sensor wires, to completely break.
So, look there… if you’re getting the bizarre temp readings and intermittent a/c, before you even order that sensor to replace it, look here first. It might save you weeks of hunting.
