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Waterloo

(12-01-2017 )74bassman Wrote: my prostar justed started doing this last week. The truck is 2010 model built in 09. I did reolace the blower motor already, but i will have to look into this harness. My truck is now leaking coolant out of the vent where the condensation comes out when you run the AC. I replaced the heater core but it is still doing it. I also do not have heat when going down the road, just blows cold air. When i stop the heat works then. could this be the harness or a blend door actuator going out?

Well, coolant out of the box... Sounds like you are going back in... Something is lose or the new core is bad.

Up under the hood is another blend door actuator, it is located on the side of the fresh air filter box. They rarely fail, but there is one there. You will have to remove the windshield wiper cowl to get to it up at the firewall... Also, it is a different part number than the two inside the cab in your dash.

I would also head to your local International dealer and get this harness 3865234C92 if you have not yet.

If the blower motor is not running, I would remove and bench test it to rule out a wiring issue. I thought mine was bad until I bench tested it, it was not the blower, it worked. The above harness should solve most blower motor issues. See my warning below... It does not fix everything.

Check the blend door actuators to make sure they are working. You should hear the blend doors opening and closing. If not, more than likely a bad actuator. I would also check to see if they are getting power from the HVAC control unit to the actuators. I have had to replace mine twice already, the HVAC control unit, it was not sending the signal to the top blend door actuator.

Here are the wiring schematics to your truck... http://bodybuilder.navistar.com/General/...s08339.pdf

Also, check all of the wiring going to the HVAC control, I found a broken wire up under the dash and repaired. No clue how that happened, but it did... No relation to the blend door issues I was having. Inspect ALL wiring.

In the fuse block up top, check the 30 amp blower motor fuse, it is front center as you are looking at the block. They tend to overheat and melt the plastic block. I would keep 30 amp fuses on hand, they tend to fail. They will test good, but are not, the same can be said for the other fuses. I tend to replace mine annually. It sucks, but normally solves other issues.

One other thing, "THE WARNING", at least on my ProStar, do not run the blower motor on the highest setting, you can go to the position just before it, but not full blast. If I run mine on high, all the way up, the motor overheats and quits working. Only way I have found to fix is to remove the blower motor and unplug it, then plug it back in along with the Linear Power Modulator. A real PIA. this resets and everything then works.

And last but not least, find your Ambient Air Temperature Sensor and get it out in the open... I dug mine out from under the radiator and hooked up to the windshield wiper cowl where the hood and driver door meet. Here is a photo...

Moving that sensor solved all of my AC issues, and there were many, thousands of dollars worth.

I hope this helps... Those wiring schematics will be your new friend. ;-)