95 Prelude...A/C not working...

[Pickleteg]

Ok guys, this is the deal. The A/C worked just fine in my Prelude until I pulled the engine and put it back in. Now, when I push the A/C button it does not light up and of course nothing happens...air blows but the compressor never kicks on. I checked all the fuses and they are good. I also ran the car with the A/C button on and manually shorted the pressure switch...nothing. Now when I apply 12 volts to the compressor it engages. Both rad fans come on when the engine gets hot enough. I know I put way too much info here but I wanted to eleminate anything I could.

Any ideas guys?

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[Romeo]

Well for one thing, the climate control unit is bad about shorting out in those. Had it happen to 2 of them in my old prelude.

[Pickleteg]

Ya.. makes me wonder. I know by looking at a wiring diagram that the A/C switch gets its power from the fan speed switch....I am hoping it is something different though LOL.

[AnthonyF]

Did you refill it with freon?

The A/C could be working just fine, but if there is No freon in the system, it will not turn on.

So, first off, charge the A/C system (the right way, not that autozone can shit) Put UV dye in the system to see if you have any leaks. Once you charge the system with freon and it still doesnt work, then you check the electrical.

-Ant.

[Pickleteg]

I am pretty sure it is electrical because by bypassing the pressure switch I eliminated the Freon as being an issue.

[AnthonyF]

Why would you do that? That sounds like one of the dumbest damn things to do.

So you bypassed it, so when the A/c leaks out you'll never know. You will just have a dry compressor engaging for no reason other than drag and to burn it out quicker?

Sounds intelligent.

-Ant.

[EmminoDaGreat]

Usually you do not have to discharge an ac system when pulling a motor... especially a honda...

[AnthonyF]

^Why is that? We always suck the freon out and disconnect the A/C lines.

-Ant.

[Barefoot]

^Why is that? We always suck the freon out and disconnect the A/C lines.

-Ant.

becuase its very easy to move around the system. ive done countless swaps an never had to touch the a/c cars trucks and vans. there are a few ive had to disconnect so yah.

[Pickleteg]

Why would you do that? That sounds like one of the dumbest damn things to do.

So you bypassed it, so when the A/c leaks out you'll never know. You will just have a dry compressor engaging for no reason other than drag and to burn it out quicker?

Sounds intelligent.

-Ant.

Guy...I bypassed it for a quick second for troubleshooting....if in fact the AC charge was low then the compressor clutch would have engaged and the fans would have came on.

[AnthonyF]

^My name isn't Guy. My employee's name is Guy (which is a Honda Tech), i thought that was pretty obvious by my IA name.

If the Freon Level is too low, it still will not engage. It needs a certain amount for it to engage the compressor. Again, start from the beginning.If you want to fiddle with hires, go right ahead.

-Ant.

[Pickleteg]

Here is some good help from a guy on HT.com:


If A/C indicator light is not comming on then it's probably a wiring issue.
Most Honda/Acura A/C switches are 2PST, [2 poles on/off] and close a ground circuit, ground input comes from blower motor speed switch, [blower motor must be on for A/C to work] one pole supplies a ground for the indicator bulb, [LED] and the other supplies a ground to the A/C thermostat, which in turn supplies a ground, [when closed] to the A/C pressure pressure switch, which in turn supplies a ground the the A/C compressor clutch relay, or to the ECU/ECM that in turn sends a ground to the A/C compressor clutch relay that in turn supplies the compressor clutch with 12V+.

So find A/C compressor relay and make sure there is power, [12V+] on both the relays coil, [#85 or #86, hot when ign. switch on] and relays input, [#30 or #87, hot at all times] you can jump #30 and #87 to see if compressor clutch engages, if so, supply a ground to relays coil, [395 or #86, opposite of hot side obviously] to see if relay works, you can even supply a ground to the pressure switch plug, [load side] to see if that will engage the compressor to narrow down where the problem may be, but with the indicator light not comming on makes me think the problem is at the A/C switch or wiring going to it.

You did turn on the blower when testing the A/C, right? 94