sh!ft

so here is my situation, ive been through 3 compressors already, and ive assumed its not the problem any more, ive checked both relays for the condensor fan and the a/c clutch both work. BUT, for some reason the a/c wont engage, but it will when i jump pins 30 and 87 in the engine bay fuse box where the clutch relay is suposed to go. the a/c light comes on and everything but just no cold air. but when i jump the pins with a paper clip or a piece of wire, the dam thing blows cold air. what could this possibly be? the sensor on the a/c drier? or could it be a short some where? it even engages when the car is off, you can hear it click on and off.


some one please help!

Former User

The ECU provides ground for the clutch relay, so the problem could be a bad ECU or a bad wire running between the ECU and clutch relay. I assume the condenser fan runs when the A/C button is pushed.

sh!ft

do you have a helms manual or an all data coppy of the wiring diagram of the car?? so i can trace the wire? i was told here in houston at john eagle honda that the relay inside the engine bay fuse box goes to the actual compressor, also to the fuse box, and then to the ecu, is this correct??

Former User

The relay has two sides, the activator and switch. The ECU provides ground to the activator circuit that switches on the compressor clutch circuit. The activator/ECU side gets power through the ignition switch and the switch/clutch side gets power from the under-hood fuse box.

sh!ft

so which connector do i need to trace the wire to and from to find out if it is loose?? assuming from the fuse box(blk n yellow), and from the ecu(blk red)

Former User

In your first post, you mentioned jumping pin 30 to 87. Not sure what these are. In the diagram that I posted, does this mean that you unplugged the compressor clutch relay and jumped terminal 4 or 2 to terminal 1 in the relay socket? And that this made the compressor clutch engage? Tell me more about what you actually did to make the A/C blow cold.

Do you have a multimeter?

sh!ft

and this is standing from the passenger side fender looking down ontop of the fuse box....with the right side of the box being the front and the left side of the box being the fire wall


ps-pm me your number so i can explain it more clearly if you dont mind

Former User

That's good. You jumped terminal 2 to terminal 1.



Two questions. When when the key is in ON(II) and the A/C button is turned on, does the condenser fan? If not, check whether fuse 17 under the dash is blown. If the fan runs, next try unplugging the pressure switch connector and then jumping the 2P connector with a wire.

sh!ft

thats what i did! i jumped the relay off of the same 2 slots on the condensor fan relay....so now the fan and clutch engage at the same time when the actual ac button is pressed inside the car. but it still makes me wonder if it will ever mess up

Former User

I already know that the compressor clutch won't engage unless you jump the clutch relay socket. Are you now saying that the condenser fan also will not run unless you similarly jump the condenser fan relay socket? If so, plug the relays back in, unplug the connector for the A/C thermostat, and jump the Blu/Wht wire to the Blu/Red wire in the thermostat connector. Does the A/C now run?

sh!ft

nooooo nononononnonnonono. lol the clutch will only engage when the condensor fan is on, thus when i push the a/c button on the climate controll lol. the fan runs reguardless

look at the picture

Former User

Nice drawings by the way, but I think we're not connecting. If the system is returned to stock, no jumper wires installed and both relays plugged in, does the condenser fan run when the engine is on and you push the A/C button? The fan CAN run without the compressor running and the compressor clutch CAN engage without the fan running. I assume, however, that the compressor clutch does not engage in this situation. Or do neither the fan nor compressor clutch work?

sh!ft

when put back to stock, the fan only runs, no wires, no nothing except the relays back in their place, and everything else untouched.

Former User

Okay good. That rules out a bad thermostat. So the probem is specifically that the clutch won't engage when the system is back to stock. In the stock state, if you jump the pressure switch connector, will the clutch now engage?

sh!ft

yes when i jum the clutch relay it turns on

Former User

Look at the diagram in post #10. I am talking about jumping the pressure switch connector not the relay.

Former User

If jumping the pressure switch connector does NOT make the compressor clutch engage, then use a multimeter to check continuity of the Blk/Red wire from terminal 3 of the clutch relay socket to terminal A17 of ECU connector A. Then also do a contuinty test of the Blu/Red-Blu/Wht wire from terminal 3 of the condenser fan relay socket to terminal A27 of ECU connector A. If both wires are fine, then the cause of your problem is most likely a bad ECU.

mewk

Hey Ron,
I am having a similar issue with my ac..
The condenser fan turns on when I push the ac button..
When jumping pins 30 and 87 at the relay nothing happens...
When jumping the pins at the pressure switch, nothing happens...

Could this be a bad compressor clutch?

sh!ft

possibly, is this a new or used or o.e.m. compressor that came with the car?

PnX-R

Geez.. Don't you just hate trying to help folks with electrical problems. I say bring it into a shop and have them check the refrigerant charge level. I didn't see you mention anything about that. From what I can make of what you're saying, the circuit seems to work fine, it just won't blow cold air by itself.

I also remember this one prelude at the shop where it has been in 3 times for the AC not working. When it came to my turn, I followed the stupid circuit and assumed ECU like mentioned earlier. Then it dawned on me, the car has been in an accident because I can tell the fenders, core support, and hood weren't OEM. Long story short, I found a corroded wire within the circuit which caused pretty much the same symptoms. Everything checked out ok, it just wouldn't blow cold air on it's own.

Electrical problems can be fun and easy when they're straight forward. It's those curve ***** that really throw you for a loop.