I have read all the threads on this same issue and done voltage checks using a meter. When I turn on the Air conditioning, the condenser fan and radiator fans do not come on. With their relays removed, jumpering between pins 1 and 2 does turn on the fan. The radiator relay turns on only the radiator fan and the A/C Condenser relay turns on both fans. The compressor clutch is not spinning with the A/C on but does click when I jumper the pins. it to a Firestone service center and they said the servicing is fine but there is no ground at pin 3 of the A/C Condenser relay. This ground comes from pin 18 of the ECM/PCM. Any words of wisdom for me be before I take it to the Honda dealer? Thanks.

 

From your description, I would suspect the ECM is denying ground to compressor and fan relays because of input from hi/lo cut-off pressure switch. If this switch opens, it means system pressure (charge) is too low to provide lubrication and compressor must not be used, hence ECM denys ground to disable compressor and fans.

Have you checked system pressure? If low, there must be a leak somewhere.

good luck

 

Thank you for the quick reply. I was thinking that from reading your other answers as all appears well electrically. I also ran the HVAC tests using the A/C controls with no errors. I was thinking there was a leak as it stopped working between last fall use and first spring use which is why I took it to Firestone and they said the servicing was fine. I will have to do some reading to figure how to do what you asked.
My copy of the document has "System on arrival had 8oz then above that it has 18oz? Also, they wrote 90/95 next to that. Would they not have checked the pressures as part their Air Conditioning performance check that I paid $47 for? Should I take it somewhere else and ask them to specifically check this?
Would it hurt anything if I removed the A/C Compressor Clutch relay and jumpered Pin 1 to Pin 2 and see if I get cold air?
I also swapped the relay with one of the same part number and no change.

 

I have the schematic for the Automatic A/C Circuit. In lookining at the pressure switch for the EX V-6, it shows pins 1 and 4 normally closed (I assume pressure is "normal" to remain in this closed position. Pin 4 goes to the CCU and Pin 1 goes to some relay module(not named) with a control block shown inside the relay box and eventually to the Guage Control Module Pin 25. Pin 2 shows a chassis ground and is shown normally open to Pin 3. When closed, a ground is supplied to the ECU Pin E14 A/C SW. It does not say what closes this contact or opens the other one. There is no relay coil and having seen this pressure switch there are tubes to it so it must just flip states mechanically when the pressures are too high or low.

What if I remove the Pressure switch connector and jumper Pins 1 and 4? Will it harm the compressor if I do it for 5 minutes to see if it starts cooling? Should I wait until someone else checks the pressures?

 

Wait, I should be able to remove the A/C Pressure Switch connector and check pin 1 to 4 on the pressure switch side for continuity(normally closed). If it is good, that means the system pressure is within limits.

If I do have continutiy between Pins 1 and 4 on the pressure switch, then I guess the ECM/PCM module is probably bad and from all that I have read that could be potentially very costly?

 

Try that test on the pressure switch.

Go to the common diy thread on top of the gen tech help forum. Under the 7th gen accords, there is a link to checking HVAC codes. It is simple to do and may help identify a problem.

 

Agree w/ both of you. You should check switch for closed contacts and if shorted, look elsewhere for problem since compressor is not engaging.

If pressure switch is open, jumper connector to see if compressor engages and cools. Don't run long if no cooling as this can damage the compressor.

It's possible for hi/lo pressure cut-out switch to fail closed.

I assume your blower is working OK, blowing air but no cooling?

good luck

 

I will follow up tommorrow hopefully. The Pressure switch is not exactly easy to get to. Thanks again.

 

I removed the plug from the pressure switch and there was a ground on Pin 2 which would go to pin 3 if the pressure switch was engaged due to system pressure issues. I then jumpered Pin 1 to Pin 4 on the plug side to simulate a normal switch position with good pressures. I started the car and the compressor clutch DID NOT engage. I then removed the compressor clutch relay and checked for a ground at Pin 3 with the car running and A/C on; still no ground at Pin 3. I also have 12v at pins 1 and 4. I then jumpered Pin 4 to Pin 2 on the Compressor clutch relay and started the car again. The compressor clutch was engaged and the air got cold very quickly. I turned off the car and removed the jumper from the pressure switch plug and reconnected it to the pressure switch. I started the car with Pin 4 to 2 jumper still connected on the compressor clutch relay socket. The A/C again worked. Both fans were running on the radiator and the compressor clutch was spinning happily.

So, I hate assuming, but the system pressure is probably good. The ECM/PCM will NOT supply a ground to Pin 3 of the compressor clutch relay.

I am at a loss what to do next besides taking it to the dealer and getting a second mortgage. My diagram does not show the inside of the ECM/PCM so I can't see what else would cause no ground to Pin 3 of the clutch relay.

 

Did you do the HVAC self-diagnostic test?