Has anyone posted a Diagnostic for 2001-2005 Buick Auto Climate Control? I just bought a 2001 Lesabre Limited and the display reads c f and nothing else!!!! The HVAC relay under the hood was missing so I put one in and still I have NOTHING....Any Ideas?

Main fault codes for the Climate control can possibly be read by a Tech II scanner.
I'm wondering if it is a wiring or connector problem.
If the relay was removed what else did they do?
Have you checked all the applicable fuses?

What other fuses would there be? I don't have the owner'* manual.

I just downloaded a manual so now I have to pull the rear seat and check some more fuses.

I just checked the fuses under the rear seat.....they are good. What next?

I have to assume you have the dual climate control with the square led display?
Can you take a photo of it and show the C&F that are showing?
Do any of the buttons light up when lights are on, does the dimmer work, even in cluster or climate control?

Here'* the pic.

Ya that is what I figured, the c & f are Celsius & Fahrenheit
Well that means the panel has power and something is illuminated.
I would go to a junk yard and find another climate control panel.
My guess is that panel is bad or something in the wiring to it is wrong.

When you say you have the manual, do you have the wiring diagram to the control head, to check all inputs?

As previously stated, a scan tool like a Tech II is necessary for proper diagnostics....to see if codes are set, or if you can even communicate with the control head....the fact someone pulled the relay, means someone was previously trying to diagnose this, and apparently got nowhere....

If no access to a Tech II, or don't want to bite the bullet by going to the Dealership, then if the inputs to the harness check out, then as Soft Ride suggests, a head from a junkyard may be the answer...

I tried a head unit...same thing.....I made an appointment with a local shop that has a Tech 2 scanner.