Ambient air temperature sensor high voltage

[kmk]

(07-31-2017 )kmk Wrote:  

(07-30-2017 )Waterloo Wrote:  

(07-30-2017 )kmk Wrote:  For anyone having issues with a/c. My truck is an 09 prostar, an old revision bcm software. Long story short the bcm was cutting power off to the compressor randomly at first then completely, after initial start up. There was nothing wrong with the system at all. The ambient temp sensor was stuck high due to corrosion at the plug. The software in my bcm compares the temp reading with static pressure from the transducer and decides whether the system is low or high on refrigerant. I never thought this was the issue. After fixing it its been running for nealy 2 months without issues. I wish International would provide more info on their programming and the different revisions. Talked to a tech that works for them, he wasnt aware of it, yet he confirmed my suspicion on a few other trucks including straight trucks later. Its beyond me why they dont provide info to their dealer network on how their software works. So if anyone has erratic ambient temp reading fix it. Its an important sensor.

That makes perfect sense! I am one of the many poor slobs on here that has fought AC issues for more than a few years on my 2008 ProStar. I would think I had it working and then right back to nothing, no AC. It was driving me nuts. Well, one day two or so months ago, more AC issues. I went and dug out that ambient air temp sensor from under my radiator. I ran the wiring and pulled the two wires out right up to the firewall. I remounted the air temp sensor up on the cowl at the driver side hood area above the door hinge. This did not solve the problem, yet.

I tore the dash apart, pulled all of the AC system out, inspected everything with a multimeter and power probe. I discovered the new HVAC control unit I had installed last year was not sending a signal to my upper blend door actuator. I drove the truck in pieces up to the dealer, exchanged the HVAC control for another, it was warrantied and installed. Well, still not working. I asked one of the techs to check with his laptop. He did a reset on the blend door, that is what he said. Whatever he did, the reset, solved the issue I came in with. I left there with ICE COLD AC! That was well over a month ago and it is still blowing ICE COLD.

The one variable here, having been through this process many many times, was that I moved the ambient air temp sensor out into the open. Whatever Ethan did at the shop was incidental. Getting that air temp sensor out from under the radiator, at least I believe, solved my issues. And that sensor, in its factory location, wrapped in tape and stuffed under the radiator was reading all over the map. Now, it is within reason and I suddenly have AC.

There is a procedure for resetting the a/c door actuators, each time you unplug a module it can lose positions and won't run the a/c. It has to do with pulling fuses, I posted it somewhere on here. I keep forgetting the order. I will try to look it up later and post it again. It really drives me insane that none of the manufacturers provide sufficient information about their equipment. When I read one of their troubleshooting guides, as much as they help, I sometimes want to pull my hairs out.

Recalibrate Procedure
-key on
-blower on
-fob to defrost
-pull fuse f1-b(power to control head)