A/C issues at idle (searched)
 

Ok so I will start with some background info. The car is a 1996 Honda Civic EX with a stock D16Y8. I have replaced damn near the entire A/C system including the compressor (twice because the first was defective), compressor belt, condenser, condenser fan, expansion valve and one of the AC lines as well due to a puncture. After replacing all of these components, the system was pressure tested and charged and seemed to work pretty well.

It started to become apparent to me that the A/C was not cooling properly at idle. I know that this will happen within reason especially in the Summer heat here in Miami, but it continued to get worse. So, I made sure again there were no leaks and that the system was changed properly and then started paying more attention to sounds of the system and the idle when the A/C was on.

At first, I noticed the condenser fan was not coming on so I replaced it, as well as the relay. This didn't solve the issue, so my attention turned to the idle, which seemed to be rough and low when the compressor was on especially in very heat soaked conditions. I also noticed that from a cold start the condenser fan would kick on just fine. I read that many A/C systems have a minimum idle they will kick the compressor on at, which makes sense given that it is belt driven. So, I figured the A/C was just falling too low for the compressor and fan to kick on.

Well, I raised the idle using the standard procedure and this did not fix my problem. When the car is at idle and no longer in the warm-up cycle, and the A/C is on, you can hear the compressor repeatedly try and kick on every few seconds but it fails and the condenser fan does not turn back on. I attached a video, but it is short due to file size limit.

Anybody know what I am missing here? Getting this A/C running properly has been a months long odyssey and it has me beat down!

Re: A/C issues at idle (searched)
 

The condenser fan must run, or the system will overpressure when the car is sitting still and start tripping on and off. In these cars the fan is wired to simply run whenever the compressor is on, there is no other control.

The overpressure also causes the compressor to use an abnormal amount of torque and drag down the idle. You are off on a goose chase when you already see the real problem-- the fan does not run.

Find why the fan does not run and fix it. If it's not the motor or the relay it is likely the fan ground wire.

Re: A/C issues at idle (searched)
 

Hey Mk, first of all just wanna say thanks you are always really helpful. Ok so a few follow up questions then.

When I replaced the condensor fan it came with a motor, so it shouldn't be that and I replaced the relay at the same time. I will check on the ground wire.

I am still puzzled though, even if it was the ground wire, why would it work properly when I cold start the car and then stop working? Any other ideas just in case?

Also, when the car is moving does the condensor usually run? The higher rpms will spin the compressor faster and the condenser gets air cooled through the bumper as well which is why it will blow cold then right? Just making sure I have a proper understanding of how everything works.

My last question is can this overpresure system over time cause me to lose freon? Even before I started this project the system would lose freon but they could never find a leak. And now I think I'm starting to run low again.

Re: A/C issues at idle (searched)
 

The devil is always in the details.

Did you flush the disassembled A/C system lines and other old components?

Did you replace the receiver dryer?

Did you put the A/C system under a deep vacuum for ~2h prior to recharging the system with refrigerant?

Did you recharge the system with the specified weight of refrigerant?

Re: A/C issues at idle (searched)
 

Sorry, forgot to mention the dryer. That too, was replaced. I didn't preform the recovery/recharge procedure that was done by an A/C shop.

Re: A/C issues at idle (searched)
 

Are you sure the mechanic/shop did all of the following?

Can you verify? I'd like to believe car mechanics and shops are fully reliable. Unfortunately, they are not.

Re: A/C issues at idle (searched)
 

I mean, I'm not sure how I'm supposed to do that at this point... I didn't watch them do it and it's not specifically outlined step by step on a receipt. The shop is pretty reputable though.

Re: A/C issues at idle (searched)
 

Hook up a manifold gauge set

Re: A/C issues at idle (searched)
 

Don worry about the refrigerant until the condenser fan runs all the time like it should. It does still get cold when the car is moving, right?

I would unplug the compressor wire to avoid that distraction, push the A/C button and wait until the fan stops, then start checking voltages. You can't test something that is intermittent until it stops working. Start with the fan motor plug (motor still plugged in, back-probe it). Measure across the motor, if you have voltage but it doesn't run-- bad motor. If there is no voltage check each wire measured to ground to see if the problem is in the power or the ground side of the circuit.

Re: A/C issues at idle (searched)
 

Focusing on the fan could be a red herring at this juncture, unless the OP is saying that the compressor clutch remains engaged when the fan fails to run. OP, please clarify.

Re: A/C issues at idle (searched)
 

So it turns out that it was the ground wire. When I went to start checking voltages the fan turned on. At first I thought maybe the connector wasn't making contact but then the issue returned. Then I thought maybe the wires in the connector might not be making contact so I tied them together while it was working. When it stopped working again I was resigned to probably having to get a new connector or splice wires but then i noticed when the fan started shorting out that there was a tiny spark from the ground connection. Turns out, it needs to be screwed down real tight to maintain proper connection and the screw/threads are prob a little rusty so I thought I had bolted it down tight enough.

Now, it works like a charm! It's amazing how much power was being drawn from that fan not running because it is much less than I thought it would be with a properly working AC system. I had some hesitations in the power band that I thought were timing related that turned out to be mostly from the fan shorting in and out.

Thanks again for the help!