so help me get my AC on?

Been out of AC for a long time now and recently decided that I should see if I can make it a project and fix it myself. I tried reading this (https://honda-tech.com/forums/tech-misc-15/%2A%2A%2Aair-conditioning-c-guide-how-works-when-doesnt%2A%2A%2A-2900177/) and several threads but I get lost so I decided to start a thread and with your help, do a step-by-step process of figuring out what's wrong and hopefully fix it.

BACKGROUND:
AC was blowing strong and cold just fine before it started to fail intermittently. It went to blowing cold - normally upon first start - then stopped blowing cold after several minutes. I would turn it off for a while, pray to the gods, then turned it back on hoping that it would blow cold air again. Sometimes it worked, sometimes it didn't. Now, it just doesn't blow cold air anymore.

WHAT I THINK I KNOW
From what I've read, few things to check first hand:

1. AC Light On?
2. Condenser Fan On?
3. 134A Pressure?
4. Compressor engaging/spinning?

WHAT TO DO NEXT

I'm pretty sure that when I turned on the AC I made sure AC is switched, light on. Question now is what should I do next? I currently don't have a gauge set or a multimeter yet. So I'm thinking maybe see if condenser is spinning or clutch engaging?


Cheers

 

The second post of that link you supplied gives all the troubleshooting you could possibly require.

A few things to check:
- no leaves or other debris stuck to the front of the condenser blocking airflow.
- that the compressor clutch successfully engages when you press the A/C button.
- you do not have an endless supply of refrigerant in the system. Are you sure you have any refrigerant?

 

Some helpful videos:

AC Clutch Repair and Noise Diagnosis:

How to Recharge an AC System:

How To Find and Repair AC Leaks:

AC Performance Test:

AC System Basics:

 

So take off all your clothes...

 

I can't say that I understand this.

From everything I've always been told AC in cars is a sealed system. Leaks are environmentally unfriendly and so must be fixed to be compliant and remain a sealed system.

And from my reading on how refrigeration works it's merely a matter of compression and expansion of gas.

That being said, how are you going to run out of refrigerant in a sealed system when operation is just compressing and expanding the gas. Where does the gas go in a sealed system?

 

If you have a leak, where do you think the refrigerant goes? Into the atmosphere of course. If you have a slow leak, the system will remain functional for a while but eventually all the refrigerant is gone and you will no longer get cool air

 

Thanks for the vids. I will re-read the second part of the link too. Meanwhile,

- No debris in front of the condenser
- No click when AC turned on, compressor is not spinning
- No manifold gauge set yet, I can't say if I have refrigerant or if it's enough

Will perform the AC test soon as I get a thermometer and read the pressure once I get a manifold gauge set.

Cheers

 

Thanks for clarifying. I understand totally if the system isn't sealed as it is supposed to be.

The impression I got from your post was that in a good sealed system you'd still eventually loose refrigerant. That's where I was confused.

You were leading the OP to test for leaks and check for refrigerant levels on the assumption of a leaky system. My total misunderstanding of your post.

 

On my way to get a test thermometer to to do the AC test, I passed by a shop which had a huge sign "FREE AC CHECK-UP". So I pulled over and had them test it.

They hooked-up a machine and said the I had good enough pressure on my refrigerant. Guy said the problem why the clutch is not engaging could be electrical. To be able to further diagnose the issue, they said that it would cost $90. I said, "Okay, thanks."

Now, I saw this thread which had a flowchart on how to diagnose an AC compressor - https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/civic-c-compressor-not-engaging-2577347/. It tells you to check thermostats, connectors, relays, switches, etc.

Question is - can I use the same guide to see if my problem might be electrical?
(I skipped to the relay and switched the condenser relay to clutch, no luck. Relay was fine)

Thanks

 

They said the pressures were good, but did they say what the pressures were? I'd be a little suspicious of a free AC check myself, as it could be like the free 29-point inspections a lot of oil change places do - pretty much a tool to make some real money.

For the pressures to be good your system has to be functioning normally. To get pressure readings from a non-functioning system you have to bypass the pressure switches and relay, which isn't hard - you just short the relay connections to power up the compressor clutch. We do that all the time in the shop. If it works fine then you know you have a bad relay, or a bad pressure switch, or a bad control module (or switch, depending on the type of system).

 

Yeah, realized that after a while. Just their ploy to get you in, then there's this and that and this is what it'll cost...

By jumping the relay, this should engage my compressor from what you're saying. I'm not sure where you'd put the wire so before I do, I uploaded a picture where I placed a wire on the terminals where I understand it should be. Not sure. Please check:



With this, once I start the engine, turn on the AC, the compressor should be running?

Thanks

 

Usually they use those little Omron relays, and they have a diagram on the side that shows the circuit and post identifications. The two terminals that have a little box connected by lines between them - thats the resistor coil that activates the solenoid. You don't want to jump those. The other two terminals in the illustration have what looks loike a door, partially open. That's the switch that's opened and closed by the solenoid, and that's the two that you want to "short", or connect together with a jumper wire. Usually its terminals #30 and #87. Usually they are diagonal from one another.

If its a different type of relay or set-up and you want to be more sure, with a multimeter you can check the whole thing. Set to ohms, pull out the relay and you should see 70 or so ohms across the resistor circuit on the relay itself. The other two prongs will have no continuity, and that's the two that you want to connect. At rest, they're open.

You can also check the relay-box end with the multimeter. Having figured out which two to connect, check them both for current (set to volts DC). One should have 12v with the ignition on, the other none. The one that doesn't have current - set the meter back to ohms and check for resistance; you should see about 2 ohms. That's the wire that feeds current down to the compressor clutch. If you just apply battery power to that from any source, with the ignition off, you should hear the clutch click on - 12 volts runs through the coil and creates a magentic field that closes the clutch.

 

Relay did have the diagram on the side and you are correct: terminals #30 & #87



I went ahead and re-attached the wire (as shown in previous picture), started the engine, turned the blower to max and turned on AC... compressor still would not engage.

Checked and made sure the wire was firmly snugged in the relay box, started the engine, blower max, AC on... compressor still would not engage.

*** Does it have to be a paper clip as seen in some videos? Or the wire should have done the job?

Then I went to check relay-box with multimeter.

- On VDC: Testing #37 & #87, ignition on, it read 13.2.
- On OHM 200 and tested the other 2 ports (#85 & #86), there was no value. It just showed "1" on the left side.

*** I don't know why there was no OHM value so I didn't go ahead and apply battery power to it yet.

Thanks

 

Rad additional tests:

Jumped low pressure switch, started engine, blower to max, AC on - compressor does not engage.

Hot wired compressor to battery, (engine off), no click. No response from compressor.

Does this mean my compressor is bad?

 

If there is no continuity in the circuit down to the compressor clutch (which should read 2 ohms resistance or so), then either the wire to the clutch is bad, the clutch itself is bad, or (if its a two-wire clutch) the ground to the clutch is bad.

It doesn't mean the compressor is bad, but practically speaking its easier and about as expensive to replace the compressor and clutch as an assembly.