I've been searching the archives and am trying to verify what needs to be done to track down my ac problem. The ac does not work at all but did up until a week ago.

The obvious thing I did first was to check the freon level. I have a simple gauge that measures the freon charge. It has green for low (0-25), blue for filled (25-45), yellow for alert (45-65) and red (65 plus) for warning. I have only had to put freon in once when the ac was not as cold as it once was. It was in the green at that time so I filled it up to 35 pounds. Perfectly cold. So when the ac stopped working I measured the freon charge amount with the ac button turned on and the temp set at 64. The gauge showed it in yellow (50). I am very confused. I know it's a cheap gauge. Any theories? Is it logical to conclude that there is enough freon in the system (perhaps overcharged) and start looking for something electrical?

Also, the ac clutch is not engaging.

What would be the next logical steps?

Any help would be most welcome. Thank you.

I would briefly hot wire the compressor just to take all the circuits out of the equation and see if the comp works. Or, you might find that with the AC compressing, the gauge reading is very low and that might be your problem. Beyond that, I take it the issue can't be over pressure ie a clogged expansion orifice?

Again to all on the BB, thanks for your patience.

As I understand it, the last suggestion of hotwiring the compressor would make it kick on. At that point I could then get an accurate charge reading on the gauge. Without the compressor engaging, the reading I get is 45. If it drops into the 20s then it is low and would need to be recharged. I have read that if the compressor does not engage, then the system cannot be charged.

Hopefully, these are my last two questions: 1) To hotwire the compressor, I think I need to pull apart the inline fuse looking thing on the compressor and hook one of the wires up to the positive side of the battery. Do I hook up the wire that goes to the front of the compressor to the positive end of the battery or do I hook up the wire that goes to the back of the compressor to the positive side of the battery? 2) If this kicks the compressor on and the gauge drops to show a low charge, can I charge the system with the compressor still hotwired?

I guess in all of this my prayer is that the system was too low on freon to kick on the clutch. Apparently, this is a safety measure.

This will probably be my last effort before going to a mechanic. Is this worth a shot?

Again, thanks to all!

Thanks, Robert. I was under the impression that the compressor was clicking on and off rapidly before he attemped to recharge. The fact that the pressostat hot wire didn't do anything is a puzzle.

He might have a bad switch on the ECC or a failed relay.

Getting warm down there yet? We still have snow on the ground.

Klaus
--
Always willing to listen, just not able to take direction.

The ac was working a week ago when I drove it. My wife borrowed my car (she likes it better than the minivan)and called me on her cell and asked, "Why isn't your ac working?" Big surprise to me.

I checked some real basic things at first like is the compressor even engaging. It wasn't. Next I checked the freon level. The freon charge was in the yellow, so it had freon in the system and perhaps too much. I do remember charging it last year for the first time. I added about half a can and it only went into the blue at that time which indicated a full charge. So the charge being in the yellow was a surprise to me. Any connection?

I also found the odd shaped box of relays on the driver's side near where the brake resevoir is and found the ac relay. It was the same yellow color and number as the one to the left of it. I swapped them and started the car with no change.

I think you mentioned another relay behind the glove box. A buddy of mine and I changed out the heater core a month ago and I did pull out the glove box to get better access to drop the panels. Though the ac worked after that, perhaps that relay has broken since then.

I could access the ECC switch by pulling out the stereo, but how would I test that? Or is there a switch it could be "switched" with?

Thanks for the advice and patience.

I never turn my AC switch off so it cannot wear out. With your switch depressed, is the green light on? Is the cabin blower working? Just checking for a bad fuse.

Klaus
--
Always willing to listen, just not able to take direction.

Klaus,

The switch is green when depressed and the blower motor works.

What do you think of the idea of hotwiring the compressor to see if it works? If the compressor works when hotwired, can I keep it hotwired long enough to take an accurate freon reading. I think the current freon reading of 45 is incorrect because the compressor is not kicking on.

If you think this is a good idea, what is the best proceedure for hotwiring a compressor?

Thanks again,
George

I have never hotwired a compressor, so I don't know which wire does what.

OK, lets go through the list one more time:

The ECC does not blink the yellow lights at start up.
The fan is in the 'auto' position and blower is running.
The AC switch is green.
The temp dials are set to 64F.
The outside temperature is over 42F.
There are no compressor clicks while the ECC system checks itself at engine startup.
Shorting the pressostat wires does not engage the compressor clutch.
Pushing on the clutch plate doesn't do anything.

All that is left is to check the fuses and the AC relay. Even with a small amount of coolant pressure, 65lbs, it should be enough to get the system cycling. The warmer the outside temperature, the greater the pressure, with the same amount of R134a.

Klaus
--
Always willing to listen, just not able to take direction.

I appreciate all the help. It still did not work. It was 45 tonight and I do not know if there is a temperature limit that would not allow the ac to work, but that just sounds like I'm grasping at straws.

FWIW, I did get an ohm meter and the pressostat read 0 with the engine off.

Would you walk me through the process of hotwiring the compressor? My knowledge is limited but I am trying to get this right.

The freon charge issue is a very interesting idea you brought up. With the car on and with the ac button depressed (but obviously not working), I have checked the charge with my gauge and it reads in the yellow. I have charged it only once before. It was in the green that time and went into the blue. The blue reads full on my gauge. Why would the gauge read yellow now? Could that be the clogged expansion orifice?

Thanks

You need to check the pressostat switch. It is on the coolant line close to the firewall. With the engine on and AC set to engage, unplug the wires and short them with a paper clip. If the compressor starts, then you need a new switch.

If the compressor fails to engage, check the clutch gap. A simple light push on the center of the clutch with a broom stick should get the clutch to engage if the gap is too large.

Klaus
--
Always willing to listen, just not able to take direction.

Klaus,

Thank you for the quick reply. I think I have seen the location of the switch. There is a wiring harness with two female connectors that plugs into two male connectors onto a freon line. Dumb question - is it the female connectors that I use the paperclip on or the male connectors? Does this make sense?

If this is not it, then with the car running and the ac turned on, I need to push on the center of compressor clutch and it should engage. If it does, then the clutch needs to be reshimed. I really don't want to turn this over to a mechanic.

Thanks again, Klaus.

George

A single connector with 2 wires. Ground the male end with a paper clip, the unplugged switch has no power. If the compressor starts, plug it back in. The pressostat checks the low pressure line; don't want to run the compressor without the freon charge.

Be careful checking the compressor clutch! the system belt will grab your wooden stick and could cause harm. Just a light touch on the center of the clutch should do it.
Or, if the air guide is off the bottom of the car, a tap from a screwdriver handle would do just as well.

Klaus
--
Always willing to listen, just not able to take direction.

Klaus,

I was really hopeful but the two suggestions did not work on my car. Just to make sure I did everything right, I shaped a paperclip into the shape of a very skinny "U", unplugged the connector and put the ends of the paperclip into the connector. All of this I did with the engine on and the ac on. Also with the engine running and ac on, I tapped the center of the ac clutch with a screw driver from underneath. It did not engage.

I saw what I think is another switch and connector on a smaller line that runs next to the line in front where the freon is added. Is the same thing possible with this connector or is it a danger because it might be the high side? There also was an electrical connector that is clamped on the side of the compressor towards the front of the car. Is this a connection to check?

Thanks,

George

The high pressure won't help. There is an AC relay behind the glovebox, but that is a pain to get to.
The wires around the compressor contain a thermal switch to turn off the compressor if it gets too hot.

When you tapped the clutch, was the pressostat bypassed with the paper clip?

Klaus
--
Always willing to listen, just not able to take direction.

Klaus,

I tried as you suggested and was very hopeful but it did not work. It was quite a humorous scene though when I took a paper clip and a cardboard box from my office. I hooked the paperclip up to bypass the pressostat, turned on the engine, turned on the ac all the way, and laid underneath the car with my suit on. Then I took the screwdriver and gently tapped and then pushed the center of the clutch. Nothing happened.

What is there left to try? And thank you for all of your help.

George

FWIW you need to do more of a 'quick hard rap' than a 'gentle push'. You won't break anything unless you use a hammer or are really really strong. Hold on to the screwdriver and give it a whack. You're trying to overcome the clutch gap long enough for the electromagnetic mechanism to take over (it's supposed to be able to do everything on its own).

Also you don't need to hit it right in the very center. You just need to get the outside half of the clutch moving in towards the inside half.
--
1998 V70 AWD->FWD Turbo 200k+

When I get home from work, I will give it a go by using the screwdriver with "a quick hard rap" while still having the pressostat bypassed. We'll see what happens and I will post the results. Thanks.

No I did not have the pressostat bypassed when tapping the clutch. I had plugged it back into the switch. So the process is to have the pressostat bypassed with a paperclick, have the engine running and the ac on and then tap the clutch. I'm tempted to do that right now but I would be late for work. I will do this on my lunch break and post the results. Thanks to all who are helping me through this.

If you've got an ohmmeter you can also check the Pressostat for resistance. It should be 0 ohm with the engine off.

When you start the car, are you getting any flashing (recirc+a/c lights blinking for 20 seconds or so)?

Have you checked the pressure while you were doing it? If it had fallen too low the safety switch will keep the compressor from kicking on. Granted, it falling significantly should clue in to a leak.. BTW, you should have ~46psi.
--
If you're not driving it "like its stolen," are you really driving?

Thanks for the response. I don't have an ohmmeter but could borrow one. I am kind of a novice at this but usually figure it out with the guidance of the BB so could you tell me the process of checking the pressostat?

I am not getting any flashing lights on the ac and recirculating lights on the automatic climate control.

I can check the charge of freon. I am not sure it is up to 46. My inexpensive gauge shows it in the yellow area which I think is in the 40 range.

Finally, and I don't know if this is related to the ac but my cooling fan stayed on for about 5 minutes when the car was shut off yesterday. That has never happened before even on the hottest days. It was in the 50s here yesterday. Any relation?

I have a feeling the BB is going to help me through this and it may also benefit someone else as the weather gets warmer.

Klaus,

Night has fallen here. This will my project for tomorrow after coming home from work. I will give you and the BB an update.

Have a good night.

Thanks,
George