98 lx with 4 cyl. AT w/manual hvac control. All lights work as they should. During high humidity days, there is no signal to trigger the a/c relay. When the humidity drops the system will work intermittently. I do not have any codes from the hvac control. I have unplugged and plugged the evaporator thermostat and after a delay the system works for awhile.
I have removed and inspected the circuit board. Found no obvious signs of a problem. Used an Ohm meter to test between the terminals for the jumper wire and had continuity. I am second guessing myself that this is the proper way to check if I need the jumper wire.
I am thinking I should just do the jumper wire to eliminate the board. All the posts I have read on the subject state the hvac lights go out when the board is bad. As I said in the beginning, my lights work.
Evap tstat maybe?

 

Does anybody have any ideas? The misses is tired of driving without air conditioning.

 

Suggest checking yel/grn wire at AC pressure switch connector when AC is commanded On. It should show a ground connection from AC control board. If not the AC control board has a fault.

If a ground is present on Yel/Grn, disconnect AC pressure switch and check switch side contacts for short (switch closed zero resistance). If open (infinite resistance), then either your charge is low or AC pressure switch is faulty.

good luck

 

Thanks Texas. I was just looking at a wiring diagram and decided to test that tonight.

 

no ground at that wire and the switch is good. I jumped the b/r wire and the system operates. Now I need to trace it back.

 

The ground is supplied by AC control board, so either a fault in the wiring or connector, or a faulty control board.

Check the G401 (ground for the AC/Heater Control Board is good.

good luck

 

Texas, can you tell me where the G401 is? Also where can I find the heater board schematic?

 

G401 is on the driver's kick panel area behind kick panel underneath the under-dash fuse box.

The Honda shop manual shows only an abbreviated diagram and no pics of circuit board.

You may be able to find a free shop manual online, or purchase from automanualsource.com for $22. I think someone found an free online manual yesterday.

good luck