2003 Accord EX-v6, WITHOUT Navigation. Three days ago, only had low-speed fan operation on blower. All HVAC controls worked, including AC. Yesterday, fan buttons would NOT turn on fan, AC, Recirc, or any of the HVAC controls. Some past posts spoke to replacing the blower resistor. I purchased an aftermarket resistor,installed it, and that did not bring the lower portion of the display back to life, nor operate the blower or other HVAC functions. The under-hood relays only have the icons, and I can figure out a couple of them, but nothing relates to HVAC. I DID find a 40amp fuse for heater motor, but the transparent top shows a solid fuse strip, so that seems to be ok. Are ANY of the relays under the hood related to the HVAC system besides that 40amp fuse in position #21? Which, if any, of the interior fuses are related to the fan/HVAC system? My interior fuse block is on the drivers side kick-panel, and no other fuse block is in the interior on this vehicle. The fuse descriptors don't show anything related to 'FAN' or 'HVAC' besides #5's 7.5 amp RADIO fuse. Is there a description of those positions online? I've found, online, a listing of the fuses, but no descriptors beyond the abbreviations. The owners manual only has the same abbreviations as on the kick-panel cover of the fuse block.

An Odd Addition: the outside temperature display is only showing '---' for the temperature. Is that related to the non-operational HVAC?

 

UPDATE: After reading through a post on another forum, I checked Fuse #30, a 7.5 Amp fuse noted as HAC. I found it was in wrong position. I pulled it on Sunday,looking for a break, and slipped it into #29. Returning it to #30 gave me power back to the HVAC controls. I had returned the original DENSO blower motor resistor, after my first posting, and found that I only had one speed, LOW. I pressed the defroster button and the blower motor automatically went to HIGH speed. I could go DOWN through the speeds, on defrost, to low, but not back up. I put in the aftermarket resistor and had the same functions: I pressed the defroster button and the blower motor automatically went to HIGH speed. I could go down through the speeds to low, but not back up to high, unless I pressed the Defrost button, again. I returned the DENSO original resistor to its position. (i don't have a tester to check for resistance.)

If the blower resistor was bad, would the blower motor work at high speed on defrost, and allow me to go down through the speeds? What other locations do I need to explore for connections that aren't working on the up-speeds for the fan-speed switch?

 

Have you checked the fan switch and connections to the motor to make sure nothing else is wrong?

 

I've had the underdash cover off to replace the resistor. Checked the connection to the blower. that was solid. My fan switch are two buttons that are marked with arrows that point up and down. the UP button does not change speeds. The down button will reduce the fan speed from high fan speed defrost setting. I can't get back into the dash (yet) to check on the fan switch connection.