HVAC Problems- '00 4.6 HSE

[Paul K]

Hi Guys,
I think I'm having a problem with my heating control unit. The old one went bad- screen was unreadable, as the green numbers started to have bits of them missing. So I took it back to the dealer, and got a whole new unit under warranty. Then it started blowing on the setting below full blast for 30 seconds, switch off, then do it again- the whole time. This was on 'auto', drivers and passengers sides both at 68 degrees. So I took it back yesterday and they told me the sensor was bad. Now the fan runs all the time (for the 3 hour drive home) at the setting above low (you can't tell fan speed because it just says 'auto'). Is this right? I seem to remember when I bought the rig, the fan would run, then slow down as it reached temp. It does seem to be at 68 degrees but I am not sure about the fan running that fast all the time. Sorry this is so long-winded- I guess I'm asking how yours operates. The engine temp is coming up correctly.
Cheers and thanks in advance,
Paul.

[troverman]

The P38 Climate Control is not known for consistency or reliabliity. Does your screen have the book and exclamation mark lit up next to outside temp? If so, this indicates a fault. Mine typically blows hard for a second then stays at fan speed wheel is set to. Auto seems to work--but yes I think the fan does stay on at a constant speed. You're right, though, it should start fast, then slow way down when it reaches temperature. Of course, mine has the book symbol.