2024 F150 XLT heater problem?

[jimswood]

Didnt get any responses to my last post so will try it this way. BTW, thanks for the add to the group... i am trying to diagnose a heater problem referred to in my last post. can anyone explain the operational difference between the when setting temp & fan speed 'manually" and when using the auto button? i purchased a temp probe to monitor the dash outlet temp and it appears that the whole system is automatic. i originally thought that if the auto button wasnt utilized, that the hvac would operte as a manual system does. but by monitoring the temp probe, say if i set the temp for 80, the temp coming out of the registers will climb apparently until the actual cab temp starts responding, then the register temp goes up or down until the cab temp stabilizes. i found a copy of the truck repair manual online but doesnt really help...TIA

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[Pcabe5]

Just my understanding of the system.

Manual allows you to control which vents you selected and fan speed. The system still uses the temperature you set and uses vent and cabin temperature sensors to regulate the temperature to achieve your set temp.

Auto will select the appropriate vent and fan speed automatically, while still using the same vent and cabin temperature sensors to achieve your set temp.