A/C problem after battery died

[woodworkingnw]

Have only had this 2017 for 1 month. Has 100K on it. Took it on a 3,000 mile roadtrip and the A/C quit working. Examined the blower motor resistor and it was melted. Wiggled the connection for the remainder of the trip to keep it working. Ordered a new resistor and pigtail. The morning I went to replace it the battery was dead. It wouldn't hold a charge so I replaced it. It was still the original battery.

Replaced the resistor, pigtail, and reset the battery using a Auto MD808. Now the front blower will work when on A/C for 10 seconds then turn off the blower for 45 seconds and continuously operate like that. If I turn off the A/C, the blower will run indefinitely on any temp setting other than low. The blower will also function at any speed that I select as long as the A/C is off. When I went out to troubleshoot and hook up the scanner last night it ran non-stop with the A/C on, but it was also much cooler.

I'm stumped on this and hopefully someone can help. I haven't checked pressure yet but I'm assuming it's fine as it worked before the batter died. The scanner isn't showing any codes.

Thanks!

 

[Motorcity muscle]

Sounds like a bad/loose electrical connection.

 

[99WhiteC5Coupe]

Have only had this 2017 for 1 month. Has 100K on it. Took it on a 3,000 mile roadtrip and the A/C quit working. Examined the blower motor resistor and it was melted. Wiggled the connection for the remainder of the trip to keep it working. Ordered a new resistor and pigtail. The morning I went to replace it the battery was dead. It wouldn't hold a charge so I replaced it. It was still the original battery.

Replaced the resistor, pigtail, and reset the battery using a Auto MD808. Now the front blower will work when on A/C for 10 seconds then turn off the blower for 45 seconds and continuously operate like that. If I turn off the A/C, the blower will run indefinitely on any temp setting other than low. The blower will also function at any speed that I select as long as the A/C is off. When I went out to troubleshoot and hook up the scanner last night it ran non-stop with the A/C on, but it was also much cooler.

I'm stumped on this and hopefully someone can help. I haven't checked pressure yet but I'm assuming it's fine as it worked before the batter died. The scanner isn't showing any codes.

Thanks!

What do you mean that you, “reset the battery”?

 

[woodworkingnw]

It’s the BMS (Battery Management System. Pretty much monitors and controls the charging system. It’s supposed to be reset when a battery is replaced.

I’m not sure it could be a loose connection as how often it’s cycling off and on is constant. Also, when I checked it in the evening, presumably when it’s cooler it operates normal.

 

[99WhiteC5Coupe]

It’s the BMS (Battery Management System. Pretty much monitors and controls the charging system. It’s supposed to be reset when a battery is replaced.

I’m not sure it could be a loose connection as how often it’s cycling off and on is constant. Also, when I checked it in the evening, presumably when it’s cooler it operates normal.

The battery section of the owner’s manual for my 2015 Expedition Limited 4x4 says nothing about the battery management system needing to be reset.

It does have a procedure listed to relearn the idle and fuel trim strategy after disconnecting the battery cables and/or replacing the battery.

Did something change on the 2017 Expedition models regarding the battery?

I’m wondering if the reset process you completed may have damaged something or changed the HVAC controller?

 

[woodworkingnw]

I don’t know what year they introduced the BMS system. I’m out of town for the next week but I’ll look more into it when I get back. The BMS is independent of the HVAC system and resetting it just zeros out all of the readings in the system and then the computer relearns it as it runs.