Hey guys. I've been searching a lot on here. I found alot of people are having my problem, but can't find any solutions. To start I have a 96 ex chasis with a 99 ex motor. I retained the 96 harness, ecu, distributor and alternator.

My AC never worked so I started troubleshooting it today. I found there was no fuse for the condensor fan, the system needed to be recharged, and the compressor clutch relay has no ground. I can't figure out the ground issue. If I ground the terminal on the clutch relay, i get nice AC. I looked at the wiring diagram and found the relay ground goes to the ecu. not sure what I can do or whats wrong. Did anyone ever figure out the solution to this problem? Like I said there are a lot of posts on this issue but no solutions. Would there be anything wrong with just throwing a toggle switch to ground on the relays ground terminal? I'm looking for any advice. Thanks in advance

 

If you push the A/C button, does the condenser fan run but the compressor clutch does not engage?

 

Yes, the fan comes on but no compressor. Everything works as it should except the ground for the ac clutch relay. If I jump it to ground the AC works great. I don't mind having a toggle switch that grounds the relay, but I read a post where someone did that, and they started getting poor gas mileage...? Maybe their problem was unrelated though. Should I give it a try? Any advice?

 

Plug everything back in, and then just unplug the pressure switch. Use a piece of wire to ground the Blu/Red wire to the chassis and then turn the key to ON(II) to see whether the compressor clutch engages. The A/C button can be off for this test.

If the clutch does not engage, measure voltage to body ground at the Blu/Red wire terminal of the unplugged pressure switch connector with the key in ON(II). What voltage do you measure?

 

can't seem to find the pressure switch. any tips on where its located on a 96 civic? it looks like from the wiring diagram the pressure switch is associated with the condensor fan relay. which works like it should. But I'll still check it

also, if the next step is check the clutch relays ground wire continuity, back to the ecu, how would i know which wire at the ecu it is?

 

The pressure switch has a 2P connector and plugs into the receiver/dryer. It has Blu/Wht and Blu/Red wires.

Do the tests in post #4.

 

ok i found it. when i grounded it, the engine idle increased but the compressor did not kick on. i tested the voltage to ground and got 4.5v

 

Next test:

Unplug ECU connector A. Locate terminal A17 (pins to Blk/Red wire). Turn the key to ON(II) and then ground the A17 terminal in the free connector to the metal frame under the dash. Does the clutch engage?

 

Hmmm... well i was out there this morning, before i read this post....I tested continuity from the ground on the relay to the A17 termination and it rand out good. I then turned on the ac with the car running and checked the a17 terminal for ground, and it had none.

If i run a jumper from the ground on the clutch relay to the negative of the battery, the ac clutch kicks on.

So I'd have to say yes if I grounded the a17 terminal, the compressor would kick on without a doubt. does this mean my computer is bad? And are there any ill effects to running a toggle switch between ground and the clutch relays negative?

 

How did you do this test? Was the ECU connector plugged in or unplugged? What did you probe?

Speculation does not answer the question. The question is whether battery voltage reaches A17 in the ECU connector and, if so, does grounding the A17 terminal in the connector cause the clutch to engage?

Depends on test result above.

 

Yes I checked for ground while the ecu was hooked up, through the back with a probe.

I will run out now and see if grounding a17 kicks on the compressor clutch. if it does, can I go ahead and put a toggle switch in?

 

Your test result does point to a bad ECU, but the test I mentioned would be nice confirmation.

You can obviously do anything you like, but replacing the ECU is the best and right solution. Buying a used ECU on eBay won't cost very much. The toggle switch is a classic bubble gum and baling wire fix.

 

Ok, sorry I'm back on here. Really wish I wasn't. But I was wondering if i could get your opinion. After putting in a switch to ground the clutch relay, Fuse 56 would blow after 2 or 3 min. I narrowed it down to the clutch field coil and not the cooling fan. I checked for resistance on the ac clutch coil, which is 2.2 ohms. I guess this means its bad and needs to be changed.

My question is should I change the field coil or whole compressor? and also where should I buy these things? Is ebay acceptable? I see the field coils going for 60 to 80 bucks. And the complete compressors going for 120. After reading a DIY on changing a compressor, I don't think I really want to get into the recovery of freon/a new drier/ and the possibility I could create leaks, which arn't currently there. Would you agree with this? And could you recommend where to buy a field coil? Thank you for all your help.

 

You can just replace the field coil. Majestic Honda online and your local Honda dealer sell the OEM part.

It is possible to replace the coil without disconnecting the refrigerant lines, if you are patient and have access to a two jaw puller tool.

 

Hi im new but was wondering did you fix it if so how thank you

 

Sounds like the the OP needed a new ECU. ECU gets the signal and revs up the engine off idle, then about 1/2 of a second later, pulls the relay coil to ground to start the compressor.

Putting a switch in was a bad idea. If you run the compressor without the condenser fan, it will overpressure and pop the relief valve or blow a hose.

 

i have all the same problems he is having but my fan wont come on i dont know what is going on everything else working fine